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Whitwell RL, Hasan HA, MacNeil RR, Enns JT. Coming to grips with reality: Real grasps, but not pantomimed grasps, resist a simultaneous tilt illusion. Neuropsychologia 2023; 191:108726. [PMID: 37931746 DOI: 10.1016/j.neuropsychologia.2023.108726] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/14/2023] [Revised: 10/27/2023] [Accepted: 11/03/2023] [Indexed: 11/08/2023]
Abstract
Investigations of grasping real, 3D objects subjected to illusory effects from a pictorial background often choose in-flight grasp aperture as the primary variable to test the hypothesis that the visuomotor system resists the illusion. Here we test an equally important feature of grasps that has received less attention: in-flight grasp orientation. The current study tested a variant of the simultaneous tilt illusion using a mirror-apparatus to manipulate the availability of haptic feedback. Participants performed grasps with haptic feedback (real grasps) and without it (pantomime grasps), reaching for the reflection of a real, 3D bar atop a background grating that induced a 1.1° bias in the perceived orientation of the bar in a separate sample of participants. Analysis of the hand's in-flight grasp orientation at early, late, and end stages of the reach showed that at no point were the real grasps biased by the illusion. In contrast, pantomimed grasps were affected by the illusion at the late and end stages of the reach. At each stage, the effect on the real grasps was significantly weaker than the effect of the illusion as measured by the mean point of subjective equality (PSE) in a two-alternative forced-choice task. In contrast, the effect on the pantomime grasps was statistically indistinguishable from the mean PSE at all three stages of the reach. These findings reinforce the idea that in-flight grasp orientation, like grasp aperture to pictorial illusions of target size, is refractory to pictorial backgrounds that bias perceived orientation.
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Affiliation(s)
- R L Whitwell
- Department of Physiology & Pharmacology, The University of Western University, Canada; Department of Psychology, The University of Western University, Canada.
| | - H A Hasan
- Department of Psychology, The University of British Columbia, Canada
| | - R R MacNeil
- Department of Psychology, The University of British Columbia, Canada
| | - J T Enns
- Department of Psychology, The University of British Columbia, Canada
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2
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Abstract
There is extensive literature debating whether perceived size is used to guide grasping. A possible reason for not using judged size is that using judged positions might lead to more precise movements. As this argument does not hold for small objects and all studies showing an effect of the Ebbinghaus illusion on grasping used small objects, we hypothesized that size information is used for small objects but not for large ones. Using a modified diagonal illusion, we obtained an effect of about 10% on perceptual judgements, without an effect on grasping, irrespective of object size. We therefore reject our precision hypothesis. We discuss the results in the framework of grasping as moving digits to positions on an object. We conclude that the reported disagreement on the effect of illusions is because the Ebbinghaus illusion not only affects size, but—unlike most size illusions—also affects perceived positions.
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3
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Abstract
Do illusory distortions of perceived object size influence how wide the hand is opened during a grasping movement? Many studies on this question have reported illusion-resistant grasping, but this finding has been contradicted by other studies showing that grasping movements and perceptual judgments are equally susceptible. One largely unexplored explanation for these contradictions is that illusion effects on grasping can be reduced with repeated movements. Using a visuomotor adaptation paradigm, we investigated whether an adaptation model could predict the time course of Ponzo illusion effects on grasping. Participants performed a series of trials in which they viewed a thin wooden target, manually reported an estimate of the target's length, then reached to grasp the target. Manual size estimates (MSEs) were clearly biased by the illusion, but maximum grip apertures (MGAs) of grasping movements were consistently accurate. Illusion-resistant MGAs were observed immediately upon presentation of the illusion, so there was no decrement in susceptibility for the adaptation model to explain. To determine whether online corrections based on visual feedback could have produced illusion-resistant MGAs, we performed an exploratory post hoc analysis of movement trajectories. Early portions of the illusion effect profile evolved as if they were biased by the illusion to the same magnitude as the perceptual responses (MSEs), but this bias was attenuated prior to the MGA. Overall, this preregistered study demonstrated that visuomotor adaptation of grasping is not the primary source of illusion resistance in closed-loop grasping.
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4
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Adaptation effects in grasping the Müller-Lyer illusion. Vision Res 2017; 136:21-31. [DOI: 10.1016/j.visres.2017.05.004] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/10/2017] [Revised: 05/04/2017] [Accepted: 05/13/2017] [Indexed: 11/22/2022]
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5
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Namdar G, Ganel T. Numerical magnitude affects online execution, and not planning of visuomotor control. PSYCHOLOGICAL RESEARCH 2017; 82:488-495. [PMID: 28108792 DOI: 10.1007/s00426-016-0837-3] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/10/2016] [Accepted: 12/26/2016] [Indexed: 11/29/2022]
Abstract
Recent literature has established a directional influence of irrelevant numerical magnitude on actions performed toward neutral objects. For example, fingers' aperture during grasping is larger when associated with large compared with small numerical digits. This interaction between symbolic magnitude and visuomotor control has been attributed to the planning stage of the action prior to motor execution. However, this assumption has not been directly tested. In two experiments, we tested whether the effects of numerical magnitude on grasping derive from action planning or from action execution. Participants were asked to grasp an object following a short visual (Experiment 1) or auditory (Experiment 2) presentation of small (1/2) or large (8/9) digits. Grasping was performed under either closed-loop (CL) or open-loop (OL) visuomotor control, for which online vision was prevented during action execution. Digit magnitude affected grip apertures in the CL condition, when online vision was allowed. However, magnitude had no effects on grip aperture in the OL condition. This pattern of results strongly suggests that the processing of numerical magnitude originates from interactions between numerical magnitude and real object size during online motor execution. Unlike previously assumed, the findings also suggest that the effect of magnitude on visuomotor control is not likely to be attributed to the motor planning stage prior to action initiation.
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Affiliation(s)
- Gal Namdar
- Department of Psychology, Ben-Gurion University of the Negev, Beer-Sheva, 8410500, Israel
| | - Tzvi Ganel
- Department of Psychology, Ben-Gurion University of the Negev, Beer-Sheva, 8410500, Israel.
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6
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Corbett JE, Venuti P, Melcher D. Perceptual Averaging in Individuals with Autism Spectrum Disorder. Front Psychol 2016; 7:1735. [PMID: 27872602 PMCID: PMC5097930 DOI: 10.3389/fpsyg.2016.01735] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/10/2016] [Accepted: 10/20/2016] [Indexed: 11/13/2022] Open
Abstract
There is mounting evidence that observers rely on statistical summaries of visual information to maintain stable and coherent perception. Sensitivity to the mean (or other prototypical value) of a visual feature (e.g., mean size) appears to be a pervasive process in human visual perception. Previous studies in individuals diagnosed with Autism Spectrum Disorder (ASD) have uncovered characteristic patterns of visual processing that suggest they may rely more on enhanced local representations of individual objects instead of computing such perceptual averages. To further explore the fundamental nature of abstract statistical representation in visual perception, we investigated perceptual averaging of mean size in a group of 12 high-functioning individuals diagnosed with ASD using simplified versions of two identification and adaptation tasks that elicited characteristic perceptual averaging effects in a control group of neurotypical participants. In Experiment 1, participants performed with above chance accuracy in recalling the mean size of a set of circles (mean task) despite poor accuracy in recalling individual circle sizes (member task). In Experiment 2, their judgments of single circle size were biased by mean size adaptation. Overall, these results suggest that individuals with ASD perceptually average information about sets of objects in the surrounding environment. Our results underscore the fundamental nature of perceptual averaging in vision, and further our understanding of how autistic individuals make sense of the external environment.
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Affiliation(s)
| | - Paola Venuti
- Department of Cognitive Science and Education, University of Trento Trento, Italy
| | - David Melcher
- Department of Cognitive Science and Education, University of TrentoTrento, Italy; Center for Mind/Brain Sciences, University of TrentoTrento, Italy
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7
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Roberts JW, Burkitt JJ, Elliott D, Lyons JL. The Impact of Strategic Trajectory Optimization on Illusory Target Biases During Goal-Directed Aiming. J Mot Behav 2016; 48:542-551. [PMID: 27362494 DOI: 10.1080/00222895.2016.1161588] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/21/2022]
Abstract
During rapid aiming, movements are planned and executed to avoid worst-case outcomes that require time and energy to correct. As such, downward movements initially undershoot the target to avoid corrections against gravity. Illusory target context can also impact aiming bias. Here, the authors sought to determine how strategic biases mediate illusory biases. Participants aimed to Müller-Lyer figures in different directions (forward, backward, up, down). Downward biases emerged late in the movement and illusory biases emerged from peak velocity. The illusory effects were greater for downward movements at terminal endpoint. These results indicate that strategic biases interact with the limb-target control processes associated with illusory biases. Thus, multiple control processes during rapid aiming may combine and later affect endpoint accuracy (D. Elliott et al., 2010 ).
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Affiliation(s)
- James W Roberts
- a Department of Kinesiology , McMaster University , Hamilton , Ontario , Canada
| | - James J Burkitt
- a Department of Kinesiology , McMaster University , Hamilton , Ontario , Canada
| | - Digby Elliott
- a Department of Kinesiology , McMaster University , Hamilton , Ontario , Canada.,b Research Institute of Sport and Exercise Sciences, Liverpool John Moores University , England
| | - James L Lyons
- a Department of Kinesiology , McMaster University , Hamilton , Ontario , Canada
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8
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Neural activity in the medial parietal area V6A while grasping with or without visual feedback. Sci Rep 2016; 6:28893. [PMID: 27381869 PMCID: PMC4933874 DOI: 10.1038/srep28893] [Citation(s) in RCA: 28] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/03/2016] [Accepted: 06/09/2016] [Indexed: 11/09/2022] Open
Abstract
Recent works have reported that grasping movements are controlled not only by the dorsolateral visual stream, as generally thought, but also by the dorsomedial visual stream, and in particular by the medial posterior parietal area V6A. To date, the grasping activity of V6A neurons has been studied only in darkness. Here we studied the effect of visual feedback on grasp-related discharges of V6A neurons while the monkey was preparing and executing the grasping of a handle. We found that V6A grasping activity could be excited or inhibited by visual information. The neural population was divided into Visual, Motor, and Visuomotor cells. The majority of Visual and Visuomotor neurons did not respond to passive observation of the handle, suggesting that vision of action, rather than object vision, is the most effective factor. The present findings highlight the role of the dorsomedial visual stream in integrating visual and motor signals to monitor and correct grasping.
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9
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Lebedev MA, Wise SP. Insights into Seeing and Grasping: Distinguishing the Neural Correlates of Perception and Action. ACTA ACUST UNITED AC 2016; 1:108-29. [PMID: 17715589 DOI: 10.1177/1534582302001002002] [Citation(s) in RCA: 35] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022]
Abstract
Vision contributes to both perception and visuomotor control, and it has been suggested that many higher brain structures specialize in one or the other function. An alternative view, presented here, is that most higher brain areas participate in both visuomotor and perceptual functions. In the anterior frontal cortex, for example, the activity of one population of neurons reflects perceptual reports about a visual stimulus, whereas the activity of an intermingled population reflects movements aimed at the same stimulus. Similarly, posterior parietal and inferior temporal areas appear to function in both visual perception and visuomotor control. Visuomotor signals in higher order cortical areas could contribute to the perception of one’s own action. They also might reflect the existence of two systems for visual information processing: one stressing accuracy for the control of movement and the other generating hypotheses about the world.
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10
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Vishton PM, Stephens NJ, Nelson LA, Morra SE, Brunick KL, Stevens JA. Planning to Reach for an Object Changes How the Reacher Perceives It. Psychol Sci 2016; 18:713-9. [PMID: 17680943 DOI: 10.1111/j.1467-9280.2007.01965.x] [Citation(s) in RCA: 40] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022] Open
Abstract
Three experiments assessed the influence of the Ebbinghaus illusion on size judgments that preceded verbal, grasp, or touch responses. Prior studies have found reduced effects of the illusion for the grip-scaling component of grasping, and these findings are commonly interpreted as evidence that different visual systems are employed for perceptual judgment and visually guided action. In the current experiments, the magnitude of the illusion was reduced by comparable amounts for grasping and for judgments that preceded grasping (Experiment 1). A similar effect was obtained prior to reaching to touch the targets (Experiment 2). The effect on verbal responses was apparent even when participants were simply instructed that a target touch task would follow the verbal task. After participants had completed a grasping task, the reduction in the magnitude of the illusion remained for a subsequent verbal-response judgment task (Experiment 3). Overall, the studies demonstrate strong connections between action planning and perception.
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Affiliation(s)
- Peter M Vishton
- Psychology Department, College of William & Mary, Williamsburg, VA 23187-8795, USA.
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11
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Effects of material properties and object orientation on precision grip kinematics. Exp Brain Res 2016; 234:2253-65. [PMID: 27016090 PMCID: PMC4923101 DOI: 10.1007/s00221-016-4631-7] [Citation(s) in RCA: 25] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/26/2015] [Accepted: 03/15/2016] [Indexed: 12/02/2022]
Abstract
Successfully picking up and handling objects requires taking into account their physical properties (e.g., material) and position relative to the body. Such features are often inferred by sight, but it remains unclear to what extent observers vary their actions depending on the perceived properties. To investigate this, we asked participants to grasp, lift and carry cylinders to a goal location with a precision grip. The cylinders were made of four different materials (Styrofoam, wood, brass and an additional brass cylinder covered with Vaseline) and were presented at six different orientations with respect to the participant (0°, 30°, 60°, 90°, 120°, 150°). Analysis of their grasping kinematics revealed differences in timing and spatial modulation at all stages of the movement that depended on both material and orientation. Object orientation affected the spatial configuration of index finger and thumb during the grasp, but also the timing of handling and transport duration. Material affected the choice of local grasp points and the duration of the movement from the first visual input until release of the object. We find that conditions that make grasping more difficult (orientation with the base pointing toward the participant, high weight and low surface friction) lead to longer durations of individual movement segments and a more careful placement of the fingers on the object.
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12
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Alphonsa S, Dai B, Benham-Deal T, Zhu Q. Combined visual illusion effects on the perceived index of difficulty and movement outcomes in discrete and continuous fitts' tapping. PSYCHOLOGICAL RESEARCH 2014; 80:55-68. [PMID: 25535018 DOI: 10.1007/s00426-014-0641-x] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/22/2014] [Accepted: 12/11/2014] [Indexed: 10/24/2022]
Abstract
The speed-accuracy trade-off is a fundamental movement problem that has been extensively investigated. It has been established that the speed at which one can move to tap targets depends on how large the targets are and how far they are apart. These spatial properties of the targets can be quantified by the index of difficulty (ID). Two visual illusions are known to affect the perception of target size and movement amplitude: the Ebbinghaus illusion and Muller-Lyer illusion. We created visual images that combined these two visual illusions to manipulate the perceived ID, and then examined people's visual perception of the targets in illusory context as well as their performance in tapping those targets in both discrete and continuous manners. The findings revealed that the combined visual illusions affected the perceived ID similarly in both discrete and continuous judgment conditions. However, the movement outcomes were affected by the combined visual illusions according to the tapping mode. In discrete tapping, the combined visual illusions affected both movement accuracy and movement amplitude such that the effective ID resembled the perceived ID. In continuous tapping, none of the movement outcomes were affected by the combined visual illusions. Participants tapped the targets with higher speed and accuracy in all visual conditions. Based on these findings, we concluded that distinct visual-motor control mechanisms were responsible for execution of discrete and continuous Fitts' tapping. Although discrete tapping relies on allocentric information (object-centered) to plan for action, continuous tapping relies on egocentric information (self-centered) to control for action. The planning-control model for rapid aiming movements is supported.
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Affiliation(s)
- Sushma Alphonsa
- Division of Kinesiology and Health, University of Wyoming, 1000 East University Avenue, Laramie, 82071, Wyoming, USA.,Department of Special Education and Rehabilitation, Utah State University, 2865 Old Main Hill, Logan, Utah, 84322, USA
| | - Boyi Dai
- Division of Kinesiology and Health, University of Wyoming, 1000 East University Avenue, Laramie, 82071, Wyoming, USA
| | - Tami Benham-Deal
- Division of Kinesiology and Health, University of Wyoming, 1000 East University Avenue, Laramie, 82071, Wyoming, USA
| | - Qin Zhu
- Division of Kinesiology and Health, University of Wyoming, 1000 East University Avenue, Laramie, 82071, Wyoming, USA.
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13
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Abstract
The visual system summarizes average properties of ensembles of similar objects. We demonstrated an adaptation aftereffect of one such property, mean size, suggesting it is encoded along a single visual dimension (Corbett, et al., 2012), in a similar manner as basic stimulus properties like orientation and direction of motion. To further explore the fundamental nature of ensemble encoding, here we mapped the evolution of mean size adaptation over the course of visually guided grasping. Participants adapted to two sets of dots with different mean sizes. After adaptation, two test dots replaced the adapting sets. Participants first reached to one of these dots, and then judged whether it was larger or smaller than the opposite dot. Grip apertures were inversely dependent on the average dot size of the preceding adapting patch during the early phase of movements, and this aftereffect dissipated as reaches neared the target. Interestingly, perceptual judgments still showed a marked aftereffect, even though they were made after grasping was completed more-or-less veridically. This effect of mean size adaptation on early visually guided kinematics provides novel evidence that mean size is encoded fundamentally in both perception and action domains, and suggests that ensemble statistics not only influence our perceptions of individual objects but can also affect our physical interactions with the external environment.
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Affiliation(s)
- Jennifer E. Corbett
- University of Trento, Center for Mind/Brain Sciences
- Brown University, Department of Cognitive, Linguistic, and Psychological Sciences
| | - Joo-Hyun Song
- Brown University, Department of Cognitive, Linguistic, and Psychological Sciences
- Brown University, Institute for Brain Science
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14
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van Wermeskerken M, van der Kamp J, Savelsbergh GJP, von Hofsten C. Getting the closer object? An information-based dissociation between vision for perception and vision for movement in early infancy. Dev Sci 2013; 16:91-100. [PMID: 23278930 DOI: 10.1111/desc.12006] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/29/2011] [Accepted: 07/18/2012] [Indexed: 11/27/2022]
Abstract
In human adults two functionally and neuro-anatomically separate systems exist for the use of visual information in perception and the use of visual information to control movements (Milner & Goodale, 1995, 2008). We investigated whether this separation is already functioning in the early stages of the development of reaching. To this end, 6- and 7-month-old infants were presented with two identical objects at identical distances in front of an illusory Ponzo-like background that made them appear to be located at different distances. In two further conditions without the illusory background, the two objects were presented at physically different distances. Preferential reaching outcomes indicated that the allocentric distance information contained in the illusory background affected the perception of object distance. Yet, infants' reaching kinematics were only affected by the objects' physical distance and not by the perceptual distance manipulation. These findings were taken as evidence for the two-visual systems, as proposed by Milner and Goodale (2008), being functional in early infancy. We discuss the wider implications of this early dissociation.
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Affiliation(s)
- Margot van Wermeskerken
- Research Institute MOVE, Faculty of Human Movement Sciences, VU University, The Netherlands.
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15
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Holmes SA, Mulla A, Binsted G, Heath M. Visually and memory-guided grasping: Aperture shaping exhibits a time-dependent scaling to Weber’s law. Vision Res 2011; 51:1941-8. [PMID: 21777599 DOI: 10.1016/j.visres.2011.07.005] [Citation(s) in RCA: 31] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/03/2011] [Revised: 07/04/2011] [Accepted: 07/05/2011] [Indexed: 10/18/2022]
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16
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Chiou RYC, Wu DH, Tzeng OJL, Hung DL, Chang EC. Relative size of numerical magnitude induces a size-contrast effect on the grip scaling of reach-to-grasp movements. Cortex 2011; 48:1043-51. [PMID: 21889134 DOI: 10.1016/j.cortex.2011.08.001] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/25/2010] [Revised: 03/16/2011] [Accepted: 07/20/2011] [Indexed: 10/17/2022]
Abstract
Previous research found that quantitative information labelled on target objects of grasping movement modulates grip apertures. While the interaction between numerical cognition and sensorimotor control may reflect a general representation of magnitude underpinned by the parietal cortex, the nature of this embodied cognitive processing remains unclear. In the present study, we examined whether the numerical effects on grip aperture can be flexibly modulated by the relative magnitude between numbers under a context, which suggests a trial-by-trial comparison mechanism to underlie this effect. The participants performed visual open-loop grasping towards one of two adjacent objects that were of the same physical size but labelled with different Arabic digits. Analysis of participants' grip apertures revealed a numerical size-contrast effect, in which the same numerical label (i.e., 5) led to larger grip apertures when it was accompanied by a smaller number (i.e., 2) than by a larger number (i.e., 8). The corrected grip aperture over the time course of movement showed that the numerical size-contrast effect remained significant throughout the grasping movement, despite a trend of gradual dissipation. Our findings demonstrated that interactions between number and action critically depend on the size-contrast of magnitude information in the context. Such a size-contrast effect might result from a general system, which is sensitive to relative magnitude, for different quantity domains. Alternatively, the magnitude representations of numbers and action might be processed separately and interact at a later stage of motor programming.
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Affiliation(s)
- Rocco Y-C Chiou
- Laboratories for Cognitive Neuroscience, National Yang-Ming University, Taiwan
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17
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Goodale MA. Transforming vision into action. Vision Res 2011; 51:1567-87. [PMID: 20691202 DOI: 10.1016/j.visres.2010.07.027] [Citation(s) in RCA: 201] [Impact Index Per Article: 15.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/07/2010] [Revised: 07/20/2010] [Accepted: 07/29/2010] [Indexed: 11/27/2022]
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18
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Heath M, Mulla A, Holmes SA, Smuskowitz LR. The visual coding of grip aperture shows an early but not late adherence to Weber's law. Neurosci Lett 2011; 490:200-4. [DOI: 10.1016/j.neulet.2010.12.051] [Citation(s) in RCA: 35] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/17/2010] [Revised: 12/16/2010] [Accepted: 12/21/2010] [Indexed: 10/18/2022]
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19
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Guerraz M, Caudron S, Thomassin N, Blouin J. Influence of head orientation on visually and memory-guided arm movements. Acta Psychol (Amst) 2011; 136:390-8. [PMID: 21292227 DOI: 10.1016/j.actpsy.2011.01.004] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/08/2009] [Revised: 01/04/2011] [Accepted: 01/04/2011] [Indexed: 12/25/2022] Open
Abstract
In the absence of visual supervision, tilting the head sideways gives rise to deviations in spatially defined arm movements. The purpose of this study was to determine whether these deviations are restricted to situations with impoverished visual information. Two experiments were conducted in which participants were positioned supine and reproduced with their unseen index finger a 2 dimensional figure either under visual supervision or from memory (eyes closed). In the former condition, the figure remained visible (using a mirror). In the latter condition, the figure was first observed and then reproduced from memory. Participants' head was either aligned with the trunk or tilted 30° towards the left or right shoulder. In experiment 1, participants observed first the figure with the head straight and then reproduced it with the head either aligned or tilted sideways. In Experiment 2, participants observed the figure with the head in the position in which the figure was later reproduced. Results of Experiment 1 and 2 showed deviations of the motor reproduction in the direction opposite to the head in both the memory and visually-guided conditions. However, the deviations decreased significantly under visual supervision when the head was tilted left. In Experiment 1, the perceptual visual bias induced by head tilt was evaluated. Participants were required to align the figure parallel to their median trunk axis. Results revealed that the figure was perceived as parallel with the trunk when it was actually tilted in the direction of the head. Perceptual and motor responses did not correlate. Therefore, as long as visual feedback of the arm is prevented, an internal bias, likely originating from head/trunk representation, alters hand-motor production irrespectively of whether visual feedback of the figure is available or not.
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Affiliation(s)
- Michel Guerraz
- Laboratory of Psychology and NeuroCognition, UMR 5105 CNRS - University of Savoie, BP 1104, 73011 Chambéry Cedex, France.
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20
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Heath M, Weiler J, Marriott K, Welsh TN. Vector inversion diminishes the online control of antisaccades. Exp Brain Res 2011; 209:117-27. [PMID: 21210087 DOI: 10.1007/s00221-010-2525-7] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/22/2010] [Accepted: 12/10/2010] [Indexed: 12/01/2022]
Affiliation(s)
- Matthew Heath
- School of Kinesiology, The University of Western Ontario, London, ON, N6A 3K7, Canada.
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21
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Heath M, Rival C, Westwood DA, Neely K. Time Course Analysis of Closed- and Open-Loop Grasping of the Müller-Lyer Illusion. J Mot Behav 2010; 37:179-85. [PMID: 15883115 DOI: 10.3200/jmbr.37.3.179-185] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
Abstract
The authors investigated whether the early or later stages of closed-loop (CL) and open-loop (OL) grasping movements were differentially influenced by the Müller-Lyer (ML) illusion. Participants (N = 21) reached out and grasped small (5 cm) and large (7 cm) objects embedded within fins-in and fins-out ML configurations. Grasping time (GT) was normalized, and absolute grip aperture (GA) as well as scaled illusion effects were computed at 20%, 40%, 60%, and 80% of GT. The results indicated that CL trials were refractory to the illusory array (i.e., from 20% to 80% of GT), whereas OL trials were influenced by the ML figure during that same time. Those findings suggest that CL trials were supported by unitary and metrical visual information, whereas OL trials were entirely supported by perception-based visual information.
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Affiliation(s)
- M Heath
- Department of Kinesiology and Program in Neural Science, Indiana University, Bloomington, IN 47405, USA.
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22
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Antisaccades exhibit diminished online control relative to prosaccades. Exp Brain Res 2010; 203:743-52. [PMID: 20490784 DOI: 10.1007/s00221-010-2290-7] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/13/2010] [Accepted: 05/01/2010] [Indexed: 10/19/2022]
Abstract
Convergent evidence suggests that stimulus-driven saccades (i.e., prosaccades) are mediated via online trajectory modifications (e.g., Gaveau et al. 2003). The goal of the present investigation was to determine whether manipulating the cognitive demands of a saccade influences the extent to which the response's trajectory is structured online. To that end, participants completed pro- and antisaccades (i.e., 180 degrees mirror-symmetrical transformation) to target stimuli that were continuously visible (Experiment 1) or occluded (Experiment 2) during the response. To index trajectory modifications, we computed the proportion of variance (R (2) values) explained by the spatial location of the eye at 10% increments of normalized movement time [i.e., 10, 20, ... 80, 90% of movement time (MT)] relative to the saccade's ultimate movement endpoint. The basis for this analysis is that between-task differences in the magnitude of R (2) values reflect differences in the use of feedback for online trajectory amendments. Results indicated that antisaccades produced larger R (2) values (from 40 to 80% of MT) as well as less accurate and more variable endpoints than their prosaccade counterparts. Such a pattern of results indicates that antisaccades were not controlled online to the same degree as prosaccades. In particular, we propose that the cognitive nature of the antisaccade task disrupts the normally online operation of saccade networks and renders a mode of control that is not optimized for feedback-based trajectory amendments.
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Abstract
In 1992, David Milner and I (Goodale & Milner, 1992) proposed a division of labour in the visual pathways of the primate cerebral cortex between a dorsal stream specialized for the visual control of action and a ventral stream dedicated to constructing our percepts of the visual world. Support for the perception-action distinction has come from neuroimaging experiments, human neuropsychology, and monkey neurophysiology. Differences in the timing and spatial metrics of vision-for-perception and vision-for-action have been studied in human psychophysical experiments, particularly in those that have looked at the way in which each system deals with pictorial illusions. Although the literature is not free from controversy, a large number of studies have found that actions such as grasping and reaching are often unaffected by high-level pictorial illusions, which by definition affect perception. Recent experiments have shown that for actions to escape the effects of such illusions, however, they must be highly practised actions, preferably with the right hand, and must be directed in real time at visible targets. But even though the behavioural evidence suggests that the dorsal and ventral streams make use of different timing, different metrics, and different frames of reference in carrying out their computations, there is a seamless interaction between the two streams in the production of adaptive behaviour. A full understanding of the integrated nature of visually guided behaviour will require that we specify the nature of the interactions and information exchange that occur between these two streams of visual processing.
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Affiliation(s)
- Melvyn A Goodale
- CIHR Group on Action and Perception, Department of Psychology, University of Western Ontario, London, Ontario, Canada.
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Dixon P, Glover S. Perseveration and contrast effects in grasping. Neuropsychologia 2009; 47:1578-84. [DOI: 10.1016/j.neuropsychologia.2008.12.032] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/01/2008] [Revised: 12/14/2008] [Accepted: 12/23/2008] [Indexed: 10/21/2022]
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Cuijpers RH, Brenner E, Smeets JB. Consistent haptic feedback is required but it is not enough for natural reaching to virtual cylinders. Hum Mov Sci 2008; 27:857-72. [DOI: 10.1016/j.humov.2008.07.003] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/01/2008] [Revised: 07/11/2008] [Accepted: 07/11/2008] [Indexed: 11/30/2022]
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Heath M, Maraj A, Godbolt B, Binsted G. Action without awareness: reaching to an object you do not remember seeing. PLoS One 2008; 3:e3539. [PMID: 18953411 PMCID: PMC2568811 DOI: 10.1371/journal.pone.0003539] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/27/2008] [Accepted: 09/30/2008] [Indexed: 11/25/2022] Open
Abstract
Background Previous work by our group has shown that the scaling of reach trajectories to target size is independent of obligatory awareness of that target property and that “action without awareness” can persist for up to 2000 ms of visual delay. In the present investigation we sought to determine if the ability to scale reaching trajectories to target size following a delay is related to the pre-computing of movement parameters during initial stimulus presentation or the maintenance of a sensory (i.e., visual) representation for on-demand response parameterization. Methodology/Principal Findings Participants completed immediate or delayed (i.e., 2000 ms) perceptual reports and reaching responses to different sized targets under non-masked and masked target conditions. For the reaching task, the limb associated with a trial (i.e., left or right) was not specified until the time of response cuing: a manipulation that prevented participants from pre-computing the effector-related parameters of their response. In terms of the immediate and delayed perceptual tasks, target size was accurately reported during non-masked trials; however, for masked trials only a chance level of accuracy was observed. For the immediate and delayed reaching tasks, movement time as well as other temporal kinematic measures (e.g., times to peak acceleration, velocity and deceleration) increased in relation to decreasing target size across non-masked and masked trials. Conclusions/Significance Our results demonstrate that speed-accuracy relations were observed regardless of whether participants were aware (i.e., non-masked trials) or unaware (i.e., masked trials) of target size. Moreover, the equivalent scaling of immediate and delayed reaches during masked trials indicates that a persistent sensory-based representation supports the unconscious and metrical scaling of memory-guided reaching.
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Affiliation(s)
- Matthew Heath
- School of Kinesiology, The University of Western Ontario, London, Ontario, Canada.
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Heath M, Neely KA, Yakimishyn J, Binsted G. Visuomotor memory is independent of conscious awareness of target features. Exp Brain Res 2008; 188:517-27. [DOI: 10.1007/s00221-008-1385-x] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/13/2008] [Accepted: 04/07/2008] [Indexed: 11/28/2022]
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Gosselin-Kessiby N, Messier J, Kalaska JF. Evidence for Automatic On-Line Adjustments of Hand Orientation During Natural Reaching Movements to Stationary Targets. J Neurophysiol 2008; 99:1653-71. [PMID: 18256170 DOI: 10.1152/jn.00980.2007] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Control of the spatial orientation of the hand is an important component of reaching and grasping movements. We studied the contribution of vision and proprioception to the perception and control of hand orientation in orientation-matching and letter-posting tasks. In the orientation-matching task, subjects aligned a “match” handle to a “target” handle that was fixed in different orientations. In letter-posting task 1, subjects simultaneously reached and rotated the right hand to insert a match handle into a target slot fixed in the same orientations. Similar sensory conditions produced different error patterns in the two tasks. Furthermore, without vision of the hand, final hand-orientation errors were smaller overall in letter-posting task 1 than in the orientation-matching task. In letter-posting task 2, subjects first aligned their hand to the angle of the target and then reached to it with the instruction not to change their initial hand orientation. Nevertheless, hand orientation changed during reaching in a way that reduced the initial orientation errors. This did not occur when there was no explicitly defined target toward which the subjects reached (letter-posting task 3). The reduction in hand-orientation errors during reach, even when told not to change it, suggests the engagement of an automatic error correction mechanism for hand orientation during reaching movements toward stationary targets. The correction mechanism was engaged when the task involved transitive actions directed at the target object. The on-line adjustments can occur without vision of the hand and even when target orientation is defined only by proprioceptive inputs.
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Goodale MA, Gonzalez CLR, Króliczak G. Action Rules: Why the Visual Control of Reaching and Grasping is Not Always Influenced by Perceptual Illusions. Perception 2008; 37:355-66. [DOI: 10.1068/p5876] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/22/2022]
Abstract
It is generally accepted that vision first evolved for the distal control of movement and that perception or ‘representational’ vision emerged much later. Vision-for-action operates in real time and uses egocentric frames of reference and the real metrics of the world. Vision-for-perception can operate over longer time scales and is much more scene-based in its computations. These differences in the timing and metrics of the two systems have been examined in experiments that have looked at the way in which each system deals with visual illusions. Although controversial, the consensus is that actions such as grasping and reaching are often unaffected by high-level pictorial illusions, which by definition affect perception. However, recent experiments have shown that, for actions to escape the effects of such illusions, they must be highly practiced actions, preferably with the right hand, and must be directed in real time at visible targets. This latter finding suggests that some of the critical components of the encapsulated (bottom – up) systems that mediate the visual control of skilled reaching and grasping movements are lateralised to the left hemisphere.
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Affiliation(s)
- Melvyn A Goodale
- CIHR Group on Action and Perception, Department of Psychology, University of Western Ontario, London, Ontario N6A 5C2, Canada
| | - Claudia L R Gonzalez
- CIHR Group on Action and Perception, Department of Psychology, University of Western Ontario, London, Ontario N6A 5C2, Canada
| | - Grzegorz Króliczak
- CIHR Group on Action and Perception, Department of Psychology, University of Western Ontario, London, Ontario N6A 5C2, Canada
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Lavrysen A, Elliott D, Buekers MJ, Feys P, Helsen WF. Eye—Hand Coordination Asymmetries in Manual Aiming. J Mot Behav 2007; 39:9-18. [PMID: 17251167 DOI: 10.3200/jmbr.39.1.9-18] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
Abstract
The authors investigated whether movement-planning and feedback-processing abilities associated with the 2 hand-hemisphere systems mediate illusion-induced biases in manual aiming and saccadic eye movements. Although participants' (N = 23) eye movements were biased in the direction expected on the basis of a typical Müller-Lyer configuration, hand movements were unaffected. Most interesting, both left- and right-handers' eye fixation onset and time to hand peak velocity were earlier when they aimed with the left hand than they were when they aimed with the right hand, regardless of the availability of vision for online movement control. They thus adapted their eye-hand coordination pattern to accommodate functional asymmetries. The authors suggest that individuals apply different movement strategies according to the abilities of the hand and the hemisphere system used to produce the same outcome.
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Affiliation(s)
- A Lavrysen
- Department of Biomedical Kinesiology and Center of Developmental Psychology, Katholieke Universiteit Leuven, Belgium
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32
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van Doorn H, van der Kamp J, Savelsbergh GJP. Grasping the Müller-Lyer illusion: The contributions of vision for perception in action. Neuropsychologia 2007; 45:1939-47. [PMID: 17240408 DOI: 10.1016/j.neuropsychologia.2006.11.008] [Citation(s) in RCA: 29] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/14/2006] [Revised: 11/15/2006] [Accepted: 11/16/2006] [Indexed: 11/21/2022]
Abstract
The present study examines the contributions of vision for perception processes in action. To this end, the influence of allocentric information on different action components (i.e., the selection of an appropriate mode of action, the pre-planning and online control of movement kinematics) is assessed. Participants (n=10) were presented with a shaft of various lengths (i.e., 13-20 cm) that was embedded in a Müller-Lyer figure. Picking up the shaft would, dependent on its length, either require a one- or a two-handed grasp. In different conditions participants were instructed to give a verbal judgement on the size of the shaft (VSJ); to make a manual estimation of the shaft's length (MLE); to indicate verbally whether they would grasp the shaft with one- or two hands (VAE); to actually grasp the shaft (G). We found that the Müller-Lyer figure affected the choice between using a one- or two-handed grasp, both when the participants actually grasped (G) the object and when they made a verbal estimation (VAE). The illusionary bias was of a similar magnitude as the one found in the verbal (VSJ) and manual perception task (MLE). The illusion had only a minor influence on the movement kinematics, and appears to be restricted to participants in which the grasping condition was immediately preceded by the VSJ-condition. We conclude that vision for perception contributes to the selection of an action mode, and that its contributions beyond that stage are dependent on the particular (experimental) circumstances.
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Affiliation(s)
- Hemke van Doorn
- Institute for Fundamental and Clinical Human Movement Sciences, Vrije Universiteit, Amsterdam, The Netherlands.
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33
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Cuijpers RH, Brenner E, Smeets JBJ. Grasping reveals visual misjudgements of shape. Exp Brain Res 2006; 175:32-44. [PMID: 16733703 DOI: 10.1007/s00221-006-0531-6] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/20/2005] [Accepted: 04/24/2006] [Indexed: 10/24/2022]
Abstract
There are many conditions in which the visually perceived shape of an object differs from its true shape. We here show that one can reveal such errors by studying grasping. Nine subjects were asked to grasp and lift elliptical cylinders that were placed vertically at eye height. We varied the cylinder's aspect ratios, orientations about the vertical axis and distances from the subject. We found that the subjects' grip orientations deviated systematically from the orientations that would give the mechanically optimal grip. That this is largely due to misjudging the cylinder's shape (rather than to selecting a comfortable posture) follows from the fact that the grip aperture was initially more strongly correlated with the maximal grip aperture (which is related to the expected contact positions) than with the final grip aperture (which is determined by the real contact positions). The correlation with the maximal grip aperture drops from 0.8 to 0.6 in the last 1% of the traversed distance (11% of movement time), showing that the grip aperture was anticipated incorrectly (it is automatically "corrected" at contact). The grip orientation was already strongly correlated with the grip orientation at the time of maximal grip aperture, half way through the movement (R > or = 0.7), showing that the suboptimal grip orientations were planned that way. We conclude that subjects plan their grasps using information that is based on the misperceived shape.
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34
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Lavrysen A, Helsen WF, Elliott D, Buekers MJ, Feys P, Heremans E. The type of visual information mediates eye and hand movement bias when aiming to a Müller–Lyer illusion. Exp Brain Res 2006; 174:544-54. [PMID: 16645876 DOI: 10.1007/s00221-006-0484-9] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/28/2005] [Accepted: 03/31/2006] [Indexed: 11/29/2022]
Abstract
Aiming bias typically influences perception but action towards the illusory stimulus is often unaffected. Recent studies, however, have shown that the type of information available is a predictor for the expression of action bias. In the present cyclical aiming experiment, the type of information (retinal and extra-retinal) was manipulated in order to investigate the differential contributions of different cues on both eye and hand movements. The results showed that a Müller-Lyer illusion caused very similar perturbation effects on hand and eye-movement amplitudes and this bias was mediated by the type of information available on-line. Interestingly, the impact of the illusion on goal-directed movement was smaller, when information about the figure but not the hand was provided for on-line control. Saccadic information did not influence the size of the effect of a Müller-Lyer illusion on hand movements. Furthermore, the illusions did not alter the eye-hand coordination pattern. The timing of saccade termination was strongly linked to hand movement kinematics. The present results are not consistent with current dichotomous models of perception and action or movement planning and on-line control. Rather, they suggest that the type of information available for movement planning mediates the size of the illusory effects. Overall, it has been demonstrated that movement planning and control processes are versatile operations, which have the ability to adapt to the type of information available.
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Affiliation(s)
- Ann Lavrysen
- Department of Biomedical Kinesiology, Faculty of Kinesiology and Rehabilitation Sciences, Motor Learning Laboratory, Katholieke Universiteit Leuven, Tervuursevest 101, 3001 Leuven, Belgium.
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35
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Mendoza JE, Elliott D, Meegan DV, Lyons JL, Welsh TN. The effect of the Müller-Lyer illusion on the planning and control of manual aiming movements. ACTA ACUST UNITED AC 2006; 32:413-22. [PMID: 16634679 DOI: 10.1037/0096-1523.32.2.413] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
Two experiments used Müller-Lyer stimuli to test the predictions of the planning-control model (S. Glover, 2002) for aiming movements. In Experiment 1, participants aimed to stimuli that either remained the same or changed upon movement initiation. Experiment 2 was identical except that the duration of visual feedback for online control was manipulated. The authors found that the figures visible during movement planning and online control had additive effects on endpoint bias, even when participants had ample time to use visual feedback to modify their movements (Experiment 2). These findings are problematic not only for the planning-control model but also for A. D. Milner and M. A. Goodale's (1995) two visual system explanation of illusory bias. Although our results are consistent with the idea that a single representation is used for perception, movement planning, and online control (e.g., V. H. Franz, 2001), other work from our laboratory and elsewhere suggests that the manner in which space is coded depends on constraints associated with the specific task, such as the visual cues available to the performer.
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Affiliation(s)
- Jocelyn E Mendoza
- Department of Kinesiology, McMaster University, Hamilton, Ontario, Canada
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36
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Heath M, Rival C, Neely K, Krigolson O. Müller-Lyer figures influence the online reorganization of visually guided grasping movements. Exp Brain Res 2005; 169:473-81. [PMID: 16292638 DOI: 10.1007/s00221-005-0170-3] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/04/2005] [Accepted: 07/07/2005] [Indexed: 10/25/2022]
Abstract
In advance of grasping a visual object embedded within fins-in and fins-out Müller-Lyer (ML) configurations, participants formulated a premovement grip aperture (GA) based on the size of a neutral preview object. Preview objects were smaller, veridical, or larger than the size of the to-be-grasped target object. As a result, premovement GA associated with the small and large preview objects required significant online reorganization to appropriately grasp the target object. We reasoned that such a manipulation would provide an opportunity to examine the extent to which the visuomotor system engages egocentric and/or allocentric visual cues for the online, feedback-based control of action. It was found that the online reorganization of GA was reliably influenced by the ML figures (i.e., from 20 to 80% of movement time), regardless of the size of the preview object, albeit the small and large preview objects elicited more robust illusory effects than the veridical preview object. These results counter the view that online grasping control is mediated by absolute visual information computed with respect to the observer (e.g., Glover in Behav Brain Sci 27:3-78, 2004; Milner and Goodale in The visual brain in action 1995). Instead, the impact of the ML figures suggests a level of interaction between egocentric and allocentric visual cues in online action control.
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Affiliation(s)
- Matthew Heath
- Department of Kinesiology and Program in Neural Science, Indiana University, Bloomington, IN 47405, USA.
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37
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Heath M, Rival C, Neely K. Visual feedback schedules influence visuomotor resistance to the Müller-Lyer figures. Exp Brain Res 2005; 168:348-56. [PMID: 16175361 DOI: 10.1007/s00221-005-0095-x] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/22/2005] [Accepted: 05/26/2005] [Indexed: 10/25/2022]
Abstract
We examined whether blocked or random visual feedback schedules influence visuomotor resistance to the Müller-Lyer (ML) illusion. Participants completed closed-loop (CL) and open-loop (OL) grasping movements to an object embedded within fins-in and fins-out ML configurations. In the blocked feedback schedule, CL and OL trials were completed in separate blocks of trials, whereas visual conditions were randomly interleaved in the random feedback schedule. The results of the blocked feedback schedule showed that OL, but not CL, trials were influenced in a direction consistent with the perceptual effects of the ML illusion. For the random feedback schedule, however, both CL and OL trials were influenced by the illusion. We have interpreted these results to reflect the fact that participants evoked distinct control strategies based on the predicted availability of visual feedback. Specifically, the refractory nature of CL trials in the blocked feedback schedule suggests that advance knowledge that visual feedback would be available during a response encouraged an online control strategy wherein metrical visual information supported grasping. When visual feedback was unavailable (i.e., blocked OL trials), or could not be predicted in advance of a response (i.e., random CL and OL trials), it is proposed that movements were structured offline via perception-based visual information that was "tricked" by the cognitive properties of the ML illusion.
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Affiliation(s)
- Matthew Heath
- Department of Kinesiology and Program in Neural Science, Indiana University, Bloomington, IN 47405, USA.
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Glover S, Dixon P, Castiello U, Rushworth MFS. Effects of an orientation illusion on motor performance and motor imagery. Exp Brain Res 2005; 166:17-22. [PMID: 16082537 DOI: 10.1007/s00221-005-2328-4] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/21/2004] [Accepted: 02/25/2005] [Indexed: 10/25/2022]
Abstract
Although the effect of visual illusions on overt actions has been an area of keen interest in motor performance, no study has yet examined whether illusions have similar or different effects on overt and imagined movements. Two experiments were conducted that compared the effects of an orientation illusion on an overt posture selection task and an imagined posture selection task. In Experiment 1 subjects were given a choice of grasping a bar with the thumb on the left side or right side of the bar. In Experiment 2 subjects were instructed to only imagine grasping the bar while remaining motionless. Subjects then reported which side of the bar their thumb had been placed in imagined grasping. Both the overt selection and imagined selection tasks were found to be sensitive to the orientation illusion, suggesting that similar visual information is used for overt and imagined movements, with both being sensitive to an orientation illusion. The results are discussed in terms of the visual processing and representation of real and imagined actions.
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Affiliation(s)
- Scott Glover
- Department of Experimental Psychology, University of Oxford, South Parks Road, Oxford, OX1 3UD, UK.
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39
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Bresciani JP, Gauthier GM, Vercher JL, Blouin J. On the nature of the vestibular control of arm-reaching movements during whole-body rotations. Exp Brain Res 2005; 164:431-41. [PMID: 15895218 DOI: 10.1007/s00221-005-2263-4] [Citation(s) in RCA: 36] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/22/2004] [Accepted: 12/14/2004] [Indexed: 11/28/2022]
Abstract
Recent studies report efficient vestibular control of goal-directed arm movements during body motion. This contribution tested whether this control relies (a) on an updating process in which vestibular signals are used to update the perceived egocentric position of surrounding objects when body orientation changes, or (b) on a sensorimotor process, i.e. a transfer function between vestibular input and the arm motor output that preserves hand trajectory in space despite body rotation. Both processes were separately and specifically adapted. We then compared the respective influences of the adapted processes on the vestibular control of arm-reaching movements. The rationale was that if a given process underlies a given behavior, any adaptive modification of this process should give rise to observable modification of the behavior. The updating adaptation adapted the matching between vestibular input and perceived body displacement in the surrounding world. The sensorimotor adaptation adapted the matching between vestibular input and the arm motor output necessary to keep the hand fixed in space during body rotation. Only the sensorimotor adaptation significantly altered the vestibular control of arm-reaching movements. Our results therefore suggest that during passive self-motion, the vestibular control of arm-reaching movements essentially derives from a sensorimotor process by which arm motor output is modified on-line to preserve hand trajectory in space despite body displacement. In contrast, the updating process maintaining up-to-date the egocentric representation of visual space seems to contribute little to generating the required arm compensation during body rotations.
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Affiliation(s)
- Jean-Pierre Bresciani
- UMR Mouvement et Perception, CNRS et Université de la Méditerranée, 163 Avenue de Luminy, 13288, Marseille, France,
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Franz VH, Scharnowski F, Gegenfurtner KR. Illusion Effects on Grasping Are Temporally Constant Not Dynamic. ACTA ACUST UNITED AC 2005; 31:1359-78. [PMID: 16366795 DOI: 10.1037/0096-1523.31.6.1359] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
The authors tested whether the effects of the Ebbinghaus illusion on grasping are corrected during late phases of the movement. Surprisingly, the grasp aperture was corrected neither under no-vision (N = 52) nor under full-vision (N = 48) conditions. The authors show that previous reports of a correction (e.g., S. Glover & P. Dixon, 2002a) are due to 2 artifacts: (a) inclusion of time points at which the target object was already touched and (b) erroneous statistics. This removes the central evidence on which S. Glover and P. Dixon's (2001a) planning-control model of action is based. In addition, the authors' results can help to refine more classic notions of motor control (e.g., R. Woodworth, 1899). In consequence, the authors reject S. Glover and P. Dixon's (2001a) planning-control model but not classic online-control theories.
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Affiliation(s)
- V H Franz
- Department of General and Experimental Psychology, University of Giessen, Giessen, Germany.
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41
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Abstract
Recent research [e.g., Carrozzo, M., Stratta, F., McIntyre, J., & Lacquaniti, F. (2002). Cognitive allocentric representations of visual space shape pointing errors. Experimental Brain Research 147, 426-436; Lemay, M., Bertrand, C. P., & Stelmach, G. E. (2004). Pointing to an allocentric and egocentric remembered target. Motor Control, 8, 16-32] reported that egocentric and allocentric visual frames of reference can be integrated to facilitate the accuracy of goal-directed reaching movements. In the present investigation, we sought to specifically examine whether or not a visual background can facilitate the online, feedback-based control of visually-guided (VG), open-loop (OL), and memory-guided (i.e. 0 and 1000 ms of delay: D0 and D1000) reaches. Two background conditions were examined in this investigation. In the first background condition, four illuminated LEDs positioned in a square surrounding the target location provided a context for allocentric comparisons (visual background: VB). In the second condition, the target object was singularly presented against an empty visual field (no visual background: NVB). Participants (N=14) completed reaching movements to three midline targets in each background (VB, NVB) and visual condition (VG, OL, D0, D1000) for a total of 240 trials. VB reaches were more accurate and less variable than NVB reaches in each visual condition. Moreover, VB reaches elicited longer movement times and spent a greater proportion of the reaching trajectory in the deceleration phase of the movement. Supporting the benefit of a VB for online control, the proportion of endpoint variability explained by the spatial location of the limb at peak deceleration was less for VB as opposed to NVB reaches. These findings suggest that participants are able to make allocentric comparisons between a VB and target (visible or remembered) in addition to egocentric limb and VB comparisons to facilitate online reaching control.
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Affiliation(s)
- Olav Krigolson
- School of Physical Education, University of Victoria, P.O. Box 3015, STN CSC, Victoria, BC, Canada V8W 3P1.
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Heath M, Westwood DA, Binsted G. The control of memory-guided reaching movements in peripersonal space. Motor Control 2004; 8:76-106. [PMID: 14973339 DOI: 10.1123/mcj.8.1.76] [Citation(s) in RCA: 64] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
Abstract
The goal of the present investigation was to explore the putative contributions of feedforward- and feedback-based processes in the control of memory-guided reaching movements. Participants (N = 4) completed an extensive number of reaching movements (2700) to 3 midline targets (20, 30, 40 cm) in 6 visual conditions: full-vision, open-loop, and four memory-guided conditions (0, 200, 400, and 600 ms of delay). To infer limb control, we used a regression technique to examine the within-trial correspondence between the spatial position of the limb at peak acceleration, peak velocity, peak deceleration, and the ultimate movement endpoint. A high degree of within-trial correspondence would suggest that the final position of the limb was largely specified prior to movement onset and not adjusted during the action (i.e., feedforward control); conversely, a low degree of within-trial correspondence would suggest that movements were modified during the reaching trajectory (i.e., feedback control). Full-vision reaches were found to be more accurate and less variable than open-loop and memory-guided reaches. Moreover, full-vision reaches demonstrated only modest within-trial correspondence between the spatial position of the limb at each kinematic marker and the ultimate movement endpoint, suggesting that reaching accuracy was achieved by adjusting the limb trajectory throughout the course of the action. Open-loop and memory-guided movements exhibited strong within-trial correspondence between final limb position and the position of the limb at peak velocity and peak deceleration. This strong correspondence indicates that the final position of the limb was largely determined by processes that occurred before the reach was initiated; errors in the planning process were not corrected during the course of the action. Thus, and contrary to our previous findings in a video-based aiming task, it appears that stored target information is not extensively (if at all) used to modify the trajectory of reaching movements to remembered targets in peripersonal space.
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Affiliation(s)
- Matthew Heath
- Department of Kinesiology, Program in Neural Science, Indiana University, Bloomington, IN 47408, USA
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Cuijpers RH, Smeets JBJ, Brenner E. On the relation between object shape and grasping kinematics. J Neurophysiol 2004; 91:2598-606. [PMID: 14749319 DOI: 10.1152/jn.00644.2003] [Citation(s) in RCA: 77] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Despite the many studies on the visual control of grasping, little is known about how and when small variations in shape affect grasping kinematics. In the present study we asked subjects to grasp elliptical cylinders that were placed 30 and 60 cm in front of them. The cylinders' aspect ratio was varied systematically between 0.4 and 1.6, and their orientation was varied in steps of 30 degrees. Subjects picked up all noncircular cylinders with a hand orientation that approximately coincided with one of the principal axes. The probability of selecting a given principal axis was the highest when its orientation was equal to the preferred orientation for picking up a circular cylinder at the same location. The maximum grip aperture was scaled to the length of the selected principal axis, but the maximum grip aperture was also larger when the length of the axis orthogonal to the grip axis was longer than that of the grip axis. The correlation between the grip aperture--or the hand orientation--at a given instant, and its final value, increased monotonically with the traversed distance. The final hand orientation could already be inferred from its value after 30% of the movement distance with a reliability that explains 50% of the variance. For the final grip aperture, this was only so after 80% of the movement distance. The results indicate that the perceived shape of the cylinder is used for selecting appropriate grasping locations before or early in the movement and that the grip aperture and orientation are gradually attuned to these locations during the movement.
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Affiliation(s)
- Raymond H Cuijpers
- Department of Neuroscience, Erasmus MC, PO Box 1738, 3000 DR Rotterdam, The Netherlands.
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Action and Memory. PSYCHOLOGY OF LEARNING AND MOTIVATION 2004. [DOI: 10.1016/s0079-7421(03)45004-4] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register]
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Abstract
Optic ataxia is characterized by inaccuracies in body movements under visual control, and is a common consequence of damage to the posterior parietal lobes in humans. It is argued here that optic ataxia can be characterized as a deficit in the visual on-line guidance of actions, with action planning remaining relatively intact. This contrasts with the common view of optic ataxia as representing a deficit in the transformations that take place between visual inputs and motor outputs. Evidence in support of the planning-control view comes from the pattern of spared and disrupted behaviors in patients with optic ataxia. It is shown that spared behaviors are those that emphasize planning, whereas disrupted behaviors are those that emphasize control. In particular, recent studies have highlighted the inability of a patient with optic ataxia to make on-line adjustments to targets that change position during the movement. Taken in sum, the data from patients with optic ataxia is more consistent with the planning-control interpretation of optic ataxia than with the visuomotor transformation interpretation.
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Affiliation(s)
- Scott Glover
- Department of Experimental Psychology, University of Oxford, South Parks Road, Oxford OX1 3UD, UK.
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Meegan DV, Glazebrook CM, Dhillon VP, Tremblay L, Welsh TN, Elliott D. The Müller-Lyer illusion affects the planning and control of manual aiming movements. Exp Brain Res 2003; 155:37-47. [PMID: 15064883 DOI: 10.1007/s00221-003-1702-3] [Citation(s) in RCA: 36] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/12/2002] [Accepted: 08/27/2003] [Indexed: 10/26/2022]
Abstract
Participants made perceptual judgments about the length of, and manual aiming movements to the opposite end of, formerly visible Müller-Lyer stimuli. The Müller-Lyer illusion affected both perceptual judgments and aiming amplitude. Manipulations of stimulus duration (10 ms or 3000 ms) and memory delay length (10 ms or 3000 ms) had no impact on the illusory effect. Aiming movements executed with vision of the hand were less affected by the illusion than movements executed without vision of the hand. The effect of the illusion on aiming amplitude remained the same between peak velocity and the end of the movement even though participants were engaged in on-line control between peak deceleration and the end of the movement. This latter finding was counter to the predictions of a hypothesis (Glover 2002) stating that illusions should only affect the early (planning) stages of movement and not the late (control) stages of movement. We conclude that a single visual representation is used for perception, motor planning, and motor control.
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Affiliation(s)
- Daniel V Meegan
- Department of Psychology, University of Guelph, N1G 2W1, Guelph, Ontario, Canada.
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Raudsepp J. Horizontal-vertical illusion: continuous decrement or the deviant first guess? Percept Mot Skills 2002; 94:599-604. [PMID: 12027357 DOI: 10.2466/pms.2002.94.2.599] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022]
Abstract
Numerous studies have reported that repetitive or extensive inspection leads to short-term decrement of the horizontal-vertical illusion. The present experiment explored whether this decrement reflects a gradual decline, as previously assumed, or is better described as a singular drop-off beyond the initial evaluation. 111 student participants adjusted vertical or horizontal lines such that they appeared equally long with a perpendicular standard. There were 8 successive adjustment trials for each subject. The results suggest that a substantial component of the illusion depends on the first impression assessment. The earlier anatomical and cognitive theories of the horizontal-vertical illusion cannot incorporate this datum. However, recent findings suggest that a motor theory of illusion might accommodate the observed one-step decrement in the illusion.
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Glover S, Dixon P. Dynamic effects of the Ebbinghaus illusion in grasping: support for a planning/control model of action. PERCEPTION & PSYCHOPHYSICS 2002; 64:266-78. [PMID: 12013380 DOI: 10.3758/bf03195791] [Citation(s) in RCA: 83] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
A distinction between planning and control can be used to explain the effects of context-induced illusions on actions. The present study tested the effects of the Ebbinghaus illusion on the planning and control of the grip aperture in grasping a disk. In two experiments, the illusion had an effect on grip aperture that decreased as the hand approached the target, whether or not visual feedback was available. These results are taken as evidence in favor of a planning/control model, in which planning is susceptible to context-induced illusions, whereas control is not. It is argued that many dissociations between perception and action may better be explained as dissociations between perception and on-line control.
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