Persistence of stimulus-response compatibility effects with extended practice

Exploring the comparative adequacy of a unimanual and a bimanual stimulus-response setup for use with three-alternative choice response time tasks

Research often conceptualises complex social factors as being distinct binary categories (e.g., female vs male, feminine vs masculine). While this can be appropriate, the addition of an 'overlapping' category (e.g., non-binary, gender neutral) can contextualise the 'binary', both for participants (allowing more complex conceptualisations of the categories than the 'either/or' conceptualisation in binary tasks), and for the results (by providing a neutral baseline for comparison). However, it is not clear what the best response setup for such a task would be. In this study, we explore this topic through comparing a unimanual (N = 34) and a bimanual response setup (N = 32) for use with a three-alternative choice response time task. Crucially, one of the stimulus categories ('mixed') was composed of stimulus elements from the other two stimulus categories used in that task (Complex Task). A reference button task was included to isolate the motoric component of response registration (Simple Task). The results of the simple task indicated lower motoric costs for the unimanual compared to the bimanual setup. However, when statistically controlling for these motoric costs in the complex task, the bimanual setup had a lower error rate and faster response times than the unimanual setup. Further, in the complex task error rates and response times were higher for the mixed than the matched stimuli, indicating that responding to mixed stimuli is more challenging for encoding and/or decision making processes. This difference was more pronounced in the unimanual than the bimanual setup. Taken together these results indicate that the unimanual setup is more adequate for the reference button task, whereas the intricacy of overlapping categories in the complex task is better contained in the bimanual setup, i.e. when some response alternatives are allocated to one hand and other alternatives to the other hand.

Orthogonal Stimulus–Response Compatibility Effects Emerge Even when the Stimulus Position is Task Irrelevant

The above-right/below-left mapping advantage with vertical stimuli and horizontal responses is known as the orthogonal stimulus–response compatibility (SRC) effect. We investigated whether the orthogonal SRC effect emerges with irrelevant stimulus dimensions. In Experiment 1, participants responded with a right or left key press to the colour of the stimulus presented above or below the fixation. We observed an above-right/below-left advantage (orthogonal Simon effect). In Experiment 2, we manipulated the polarity in the response dimension by varying the horizontal location of the response set. The orthogonal Simon effect decreased and even reversed as the left response code became more positive. This result provides evidence for the automatic activation of the positive and negative response codes by the corresponding positive and negative stimulus codes. These findings extended the orthogonal SRC effect based on coding asymmetry to an irrelevant stimulus dimension.

The effect of display movement angle, indicator type and display location on control/display stereotype strength

Much research on stereotype strength relating display and control movements for displays moving in the vertical or horizontal directions has been reported. Here we report effects of display movement angle, where the display moves at angles (relative to the vertical) of between 0° and 180°. The experiment used six different controls, four display locations relative to the operator and three types of indicator. Indicator types were included because of the strong effects of the 'scale-side principle' that are variable with display angle. A directional indicator had higher stereotype strength than a neutral indicator, and showed an apparent reversal in control/display stereotype direction beyond an angle of 90°. However, with a neutral indicator this control reversal was not present. Practitioner Summary: The effects of display moving at angles other than the four cardinal directions, types of control, location of display and types of indicator are investigated. Indicator types (directional and neutral) have an effect on stereotype strength and may cause an apparent control reversal with change of display movement angle.

Test-Retest Reliability in Performance of Persons with Hemiparesis Tracking by Means of Compatibly Displayed Myoelectric Feedback Derived from Upper Limb Muscles

The aim of this study was to assess whether persons with hemiparesis will yield statistically reliable test-retest tracking performance on a procedure using limb-generated, compatibly displayed, myoelectric video feedback. A convenience sample of 50 inpatients and outpatients with upper extremity involvement of at least six months were recruited. 30 had hemiparesis and had both upper extremities tested. 20 had hemiplegia and had the nonparetic upper extremity tested. Tracking skill was measured as mean tracking error. Repeated measures analysis of variance yielded statistically significant effects of main factors: Response mode, Cursor Feedback, and Session. Extremity tested was not significant. Performance with involved limb, uninvolved limb, isometric mode, and isotonic mode all yielded positive test-retest correlations. The reliable range of tracking error obtained from subjects with hemiparesis performing a task requiring modulation of compatibly displayed myoelectric output supports the therapeutic rationale for employing compatibly displayed video feedback in the rehabilitation of motor control.

The joint flanker effect and the joint Simon effect: On the comparability of processes underlying joint compatibility effects

Previous studies observed compatibility effects in different interference paradigms such as the Simon and flanker task even when the task was distributed across two co-actors. In both Simon and flanker tasks, performance is improved in compatible trials relative to incompatible trials if one actor works on the task alone as well as if two co-actors share the task. These findings have been taken to indicate that actors automatically co-represent their co-actor's task. However, recent research on the joint Simon and joint flanker effect suggests alternative non-social interpretations. To which degree both joint effects are driven by the same underlying processes is the question of the present study, and it was scrutinized by manipulating the visibility of the co-actor. While the joint Simon effect was not affected by the visibility of the co-actor, the joint flanker effect was reduced when participants did not see their co-actors but knew where the co-actors were seated. These findings provide further evidence for a spatial interpretation of the joint Simon effect. In contrast to recent claims, however, we propose a new explanation of the joint flanker effect that attributes the effect to an impairment in the focusing of spatial attention contingent on the visibility of the co-actor.

Tactile stimulations and wheel rotation responses: toward augmented lane departure warning systems

When an on-board system detects a drift of a vehicle to the left or to the right, in what way should the information be delivered to the driver? Car manufacturers have so far neglected relevant results from Experimental Psychology and Cognitive Neuroscience. Here we show that this situation possibly led to the sub-optimal design of a lane departure warning system (AFIL, PSA Peugeot Citroën) implemented in commercially available automobile vehicles. Twenty participants performed a two-choice reaction time task in which they were to respond by clockwise or counter-clockwise wheel-rotations to tactile stimulations of their left or right wrist. They performed poorer when responding counter-clockwise to the right vibration and clockwise to the left vibration (incompatible mapping) than when responding according to the reverse (compatible) mapping. This suggests that AFIL implements the worse (incompatible) mapping for the operators. This effect depended on initial practice with the interface. The present research illustrates how basic approaches in Cognitive Science may benefit to Human Factors Engineering and ultimately improve man-machine interfaces and show how initial learning can affect interference effects.

Directional control-response compatibility relationships assessed by physical simulation of an underground bolting machine

OBJECTIVE

The authors examine the pattern of direction errors made during the manipulation of a physical simulation of an underground coal mine bolting machine to assess the directional control-response compatibility relationships associated with the device and to compare these results to data obtained from a virtual simulation of a generic device.

BACKGROUND

Directional errors during the manual control of underground coal roof bolting equipment are associated with serious injuries. Directional control-response relationships have previously been examined using a virtual simulation of a generic device; however, the applicability of these results to a specific physical device may be questioned.

METHOD

Forty-eight participants randomly assigned to different directional control-response relationships manipulated horizontal or vertical control levers to move a simulated bolter arm in three directions (elevation, slew, and sump) as well as to cause a light to become illuminated and raise or lower a stabilizing jack. Directional errors were recorded during the completion of 240 trials by each participant

RESULTS

Directional error rates are increased when the control and response are in opposite directions or if the direction of the control and response are perpendicular.The pattern of direction error rates was consistent with experiments obtained from a generic device in a virtual environment.

CONCLUSION

Error rates are increased by incompatible directional control-response relationships.

APPLICATION

Ensuring that the design of equipment controls maintains compatible directional control-response relationships has potential to reduce the errors made in high-risk situations, such as underground coal mining.

Specificity of transfer in basic and applied perceptual-motor tasks

We conducted research on transfer of skills using basic stimulus-response compatibility tasks and applied tasks requiring control of a hydraulic excavator simulator. The basic tasks show rapid acquisition of practiced spatial mappings, for which transfer is specific to the procedures used in training. The applied tasks show transfer across alternative control configurations that maintain practiced spatial mappings, as well as from part to whole practice. Transfer from simulated to real equipment also seems to occur; however, studies involving cooperation of academia and industry are needed to provide more definitive evidence on this question.

Response-effect compatibility defines the natural scrolling direction

OBJECTIVE

We evaluated alternative scrolling methods on non-touch screen computer operating systems by comparing human performance in different scrolling conditions.

BACKGROUND

The scrolling directions on current operating systems are discrepant. Few researchers have investigated how scrolling method influences users performance. The response-effect (R-E) compatibility principle can be used as a theoretical guide.

METHOD

Experiments 1 and 2 involved two successive tasks (scrolling and target content judgment) to simulate how people scroll to acquire and use off-screen information. Performance in R-E compatible and incompatible conditions was compared. Experiment 3 involved a location judgment task to test the influence of target location. Experiments 4 and 5 included a scrolling effect following the location judgment task to test the sufficient role of the scrolling effect.

RESULTS

Overall, responses were facilitated when the response direction was compatible with the forthcoming display-content movement direction (an R-E compatibility effect), when the scrolling effect was task relevant or task irrelevant. A spatial stimulus-response (S-R) compatibility effect attributable to target location was also found. When the scrolling effect was present, there were both R-E and S-R components; the R-E effect was the larger of the two.

CONCLUSION

Scrolling in the direction of content movement yielded the best performance, and the scrolling effect was the main source of the R-E compatibility effect.

APPLICATION

These findings suggest that (a) the R-E compatibility principle may be used as a general design guideline for scrolling and (b) a consistent scrolling method should be available on various operating systems.

Up or Down: Directional Stimulus-Response Compatibility and Natural Scrolling

The settings of scrolling direction (e.g., whether scrolling up or down to move the display content up) on current computer operating systems are discrepant, which may impair users’ performance and user experience. To evaluate the alternatives, we conducted two experiments. In Experiment 1, we simulated the way people read and scroll on a computer by asking participants to press the up-arrow or down-arrow key to scroll the screen. In Experiment 2, we eliminated the scrolling component by including only a location-judgment task. We examined directional stimulus-response compatibility in the scrolling task and the location-judgment task. Results showed that responses were facilitated when the control direction was compatible with the display content movement direction. This finding is consonant with the Mac OS X Lion operating system, which defines the default scrolling direction as “move content in the direction of finger movement.” We recommend that other systems adopt this directional compatible mapping.

Control-display mapping in brain-computer interfaces

Event-related potential (ERP) based brain-computer interfaces (BCIs) employ differences in brain responses to attended and ignored stimuli. When using a tactile ERP-BCI for navigation, mapping is required between navigation directions on a visual display and unambiguously corresponding tactile stimuli (tactors) from a tactile control device: control-display mapping (CDM). We investigated the effect of congruent (both display and control horizontal or both vertical) and incongruent (vertical display, horizontal control) CDMs on task performance, the ERP and potential BCI performance. Ten participants attended to a target (determined via CDM), in a stream of sequentially vibrating tactors. We show that congruent CDM yields best task performance, enhanced the P300 and results in increased estimated BCI performance. This suggests a reduced availability of attentional resources when operating an ERP-BCI with incongruent CDM. Additionally, we found an enhanced N2 for incongruent CDM, which indicates a conflict between visual display and tactile control orientations.

PRACTITIONER SUMMARY

Incongruency in control-display mapping reduces task performance. In this study, brain responses, task and system performance are related to (in)congruent mapping of command options and the corresponding stimuli in a brain-computer interface (BCI). Directional congruency reduces task errors, increases available attentional resources, improves BCI performance and thus facilitates human-computer interaction.

Investigating the nature and time-course of the modality shift effect between vision and touch

It is well known that stimuli grab attention to their location, but do they also grab attention to their sensory modality? The modality shift effect (MSE), the observation that responding to a stimulus leads to reaction time benefits for subsequent stimuli in the same modality, suggests that this may be the case. If noninformative cue stimuli, which do not require a response, also lead to benefits for their modality, this would suggest that the effect is automatic. We investigated the time-course of the visuotactile MSE and the difference between the effects of cues and targets. In Experiment 1, when visual and tactile tasks and stimulus locations were matched, uninformative cues did not lead to reaction time benefits for targets in the same modality. However, the modality of the previous target led to a significant MSE. Only stimuli that require a response, therefore, appear to lead to reaction time benefits for their modality. In Experiment 2, increasing attention to the cue stimuli attenuated the effect of the previous target, but the cues still did not lead to a MSE. In Experiment 3, a MSE was demonstrated between successive targets, and this effect decreased with increasing intertrial intervals. Overall, these studies demonstrate how cue- and target-induced effects interact and suggest that modalities do not automatically capture attention as locations do; rather, the MSE is more similar to other task repetition effects.

A memory-based model of Hick's law

We propose and evaluate a memory-based model of Hick's law, the approximately linear increase in choice reaction time with the logarithm of set size (the number of stimulus-response alternatives). According to the model, Hick's law reflects a combination of associative interference during retrieval from declarative memory and occasional savings for stimulus-response repetitions due to non-retrieval. Fits to existing data sets show that the model accounts for the basic set-size effect, changes in the set-size effect with practice, and stimulus-response repetition effects that challenge the information-theoretic view of Hick's law. We derive the model's prediction of an interaction between set size, stimulus fan (the number of responses associated with a particular stimulus), and stimulus-response transition, which is subsequently tested and confirmed in two experiments. Collectively, the results support the core structure of the model and its explanation of Hick's law in terms of basic memory effects.

Unintentional and intentional learning of noncorresponding stimulus-response associations in the Simon task

The Simon effect is a robust phenomenon that persists after extensive practice. However, several studies using a transfer paradigm have shown that the Simon effect is eliminated after practicing a location-relevant task with an incompatible spatial mapping. The present study examined whether this transfer effect is a result of implicit, procedural knowledge developed through repeated execution of noncorresponding responses in the practice session or a consequence of explicitly learning and reinstating a noncorresponding mapping rule. Results from two experiments show that, although a small part of the transfer effect may be due to residual activation of noncorresponding S-R associations from the prior task, the larger and more stable part is likely due to response-selection strategies performed intentionally in the practice task.

Attentional origins of the Simon effect: behavioral and electrophysiological evidence

An electrophysiological analysis of classification in the Garner paradigm was performed to investigate processing origins of the Simon effect. This effect is faster responding when stimulus location, though irrelevant to the task, is congruent with the response to the relevant stimulus dimension than when it is not. Participants used lateral keys to classify the timbre of tones presented to left or right headphones. Differences between S-R congruent and S-R incongruent trials were observed initially in the N2 ERP component (250 ms after stimulus onset), after the N1 component (100 ms after stimulus onset) showed evidence of a failure of selective attention to stimulus location. Reaction times to congruent and incongruent stimuli were strongly associated with the peak latency of the P3 decisional component. The results are consistent with models that attribute the Simon effect to the evidentiary weight attention assigns to spatial location when classifying the stimulus as signaling left or right.

Performance consequences of alternating directional control-response compatibility: evidence from a coal mine shuttle car simulator

OBJECTIVE

To investigate error and reaction time consequences of alternating compatible and incompatible steering arrangements during a simulated obstacle avoidance task.

BACKGROUND

Underground coal mine shuttle cars provide an example of a vehicle in which operators are required to alternate between compatible and incompatible steering configurations.

METHODS

This experiment examines the performance of 48 novice participants in a virtual analogy of an underground coal mine shuttle car. Participants were randomly assigned to a compatible condition, an incompatible condition, an alternating condition in which compatibility alternated within and between hands, or an alternating condition in which compatibility alternated between hands.

RESULTS

Participants made fewer steering direction errors and made correct steering responses more quickly in the compatible condition. Error rate decreased over time in the incompatible condition. A compatibility effect for both errors and reaction time was also found when the control-response relationship alternated; however, performance improvements over time were not consistent. Isolating compatibility to a hand resulted in reduced error rate and faster reaction time than when compatibility alternated within and between hands.

CONCLUSION

The consequences of alternating control-response relationships are higher error rates and slower responses, at least in the early stages of learning.

APPLICATION

This research highlights the importance of ensuring consistently compatible human-machine directional control-response relationships.

Aging and response selection in spatial choice tasks

Factors that make response selection more difficult, most notably incompatibility between displays and controls, degrade performance. The cost of incompatibility on performance is often much greater for older than for younger adults. To design products that accommodate decreased response selection capabilities of older adults, designers need to understand the specific ways in which response selection processes change with age. The purpose of the present paper is to review research on age-related changes in stimulus-response compatibility and response precuing effects, the two effects that are most directly linked to basic response selection processes. Several specific aspects of response selection that are particularly harmful for older adults' performance are identified. Potential applications of this research include initial guidelines for minimizing the effects of those aspects when designing for older adults.

Exploring the contributions of premotor and parietal cortex to spatial compatibility using image-guided TMS

Functional brain imaging studies have demonstrated increased activity in dorsal premotor and posterior parietal cortex when performing spatial stimulus-response compatibility tasks (SRC). We tested the specific role of these regions in stimulus-response mapping using single-pulse transcranial magnetic stimulation (TMS). Subjects were scanned using functional magnetic resonance imaging (fMRI) prior to the TMS session during performance of a task in which spatial compatibility was manipulated. For each subject, the area of increased signal within the regions of interest was registered onto their own high-resolution T1-weighted anatomic scan. TMS was applied to these areas for each subject using a frameless stereotaxic system. Task accuracy and reaction time (RT) were measured during blocks of compatible or incompatible trials and during blocks of real TMS or sham stimulation. On each trial, a single TMS pulse was delivered at 50, 100, 150, or 200 ms after the onset of the stimulus in the left or right visual field. TMS over the left premotor cortex produced various facilitatory effects, depending on the timing of the stimulation. At short intervals, TMS appeared to prime the left dorsal premotor cortex to select a right-hand response more quickly, regardless of stimulus-response compatibility. The strongest effect of stimulation, however, occurred at the 200-ms interval, when TMS facilitated left-hand responses during the incompatible condition. Facilitation of attention to the contralateral visual hemifield was observed during stimulation over the parietal locations. We conclude that the left premotor cortex is one of the cortical regions responsible for overriding automatic stimulus-response associations.

The Effects of Spatial Stimulus-Response Compatibility on Choice Time Production Accuracy and Variability

Five experiments examined the relations between timing and attention using a choice time production task in which the latency of a spatial choice response is matched to a target interval (3 or 5 s). Experiments 1 and 2 indicated that spatial stimulus-response incompatibility increased nonscalar timing variability without affecting timing accuracy and that choice reaction time practice reduced choice time production variability. These data support a "temporal discounting" model in which response choice and timing occur in series, but the interval timed is shortened to account for nontemporal processing. In Experiment 3, feedback and anticipation task demands improved choice time production accuracy. In Experiments 4 and 5, the delay between the start-timing and choice-decision signals interacted with choice difficulty to affect choice time production accuracy and variability when timing a 3- but not a 5-s interval, suggesting that attention mediates timing before and after an interruption in timing.

Anticipated action effects affect the selection, initiation, and execution of actions

This study investigated the impact of contingent action effects on response production. In Experiment 1 responses of varying intensity were initiated faster when contingently followed by auditory effects of corresponding rather than of noncorresponding intensity. This response-effect (R-E) compatibility influence was robust with respect to practice, and it was not due to persisting influences of preceding R-E episodes. These results support the conclusion that R-E compatibility reflects the impact of anticipatory effect representations in response production. Experiment 2 showed that anticipatory effect codes have an impact on early processes of response production (response selection) as well as on processes that immediately precede overt responding (response initiation). Finally, they also influence the way the actions are physically performed (response execution). The results support and specify ideo-motor theories of action control that assume movements to be controlled by anticipations of their sensorial effects.

Transfer effects of incompatible location-relevant mappings on a subsequent visual or auditory Simon task

Two experiments investigated the influence of practice with an incompatible mapping of left and right stimuli to keypress responses on performance of a subsequent Simon task, for which stimulus location was irrelevant, after a delay of 5 min or 1 week. In Experiment 1, the visual Simon effect was eliminated when the practice modality was auditory and reversed to favor noncorresponding responses when it was visual, and there was no significant effect of delay interval. In Experiment 2, significant auditory Simon effects were obtained that did not vary as a function of practice modality, with delay having only a marginal effect on the magnitude of the Simon effect. The elimination of the visual Simon effect in the transfer session is most likely due to the short-term stimulus-response associations defined for the incompatible spatial mapping remaining active during the transfer session. Because the auditory Simon effect is stronger than the visual one, more practice with the incompatible mapping may be necessary to produce reliable transfer effects for it.

Stimulus and response representations underlying orthogonal stimulus-response compatibility effects

One of the most important findings in recent years regarding response selection is that stimulus-response compatibility (SRC) effects occur for situations in which stimulus and response sets vary along orthogonal dimensions. For two-choice tasks, two types of orthogonal SRC effects are found: an overall advantage for the up-right/down-left mapping, and mapping preferences that vary as a function of position of the response apparatus and responding hand. We review evidence regarding the nature of both types of orthogonal SRC effects. Only asymmetric coding accounts have been proposed for the up-right/down-left advantage, and the evidence indicates that this asymmetry is a property of both verbal and spatial codes. Motoric and coding accounts, as well as a hybrid account based on end-state comfort, have been proposed for the second type of orthogonal SRC effect. In this case, the effects of response-apparatus position, hand, and hand posture conform more closely to predictions of the asymmetric coding accounts than to those of the motoric accounts. We also evaluate the mechanisms proposed by the alternative accounts in terms of related literature on the properties of spatial and verbal codes. Evidence indicates that spatial information is represented in categorical and coordinate codes, and both categorical spatial codes and verbal codes are asymmetric. Experiments on mental rotation suggest that it is unlikely that the direction of rotation is determined automatically by movement constraints, as the end-state comfort hypothesis suggests. An explanation in terms of salient features and referential coding can accommodate the range of orthogonal SRC effects.

Naïve and experienced judgments of stimulus-response compatibility: implications for interface design

Many design guidelines encourage maintaining stimulus-response compatibility whenever possible. Payne found that naïve judgments for different stimulus-response (S-R) mappings were not very accurate, and suggested that designers may not be able to predict whether a particular display-control configuration will lead to better performance than another. Three experiments were conducted to determine whether naïve judgments for two-choice tasks in which stimuli and responses involve left-right spatial information are sensitive to (a) the influence of S-R mode relations and (b) pure versus mixed presentation of compatible and incompatible mappings. Initial performance judgments for these conditions were not very accurate, nor were those for four-choice tasks of the type studied by Payne, but subjects' estimates of performance improved with relatively little experience using the different S-R configurations.

Sex differences in tracking performance in patients with Parkinson's disease

OBJECTIVE

To examine whether Parkinson's disease affects men and women differently, relative to age-matched controls, in manual tracking.

DESIGN

Cross-sectional exploratory study.

SETTING

Ambulatory activity center.

PARTICIPANTS

Ten men and 10 women with Parkinson's disease; 10 men and 10 women age-matched controls.

INTERVENTIONS

Patients tracked a sinewave target on a computer monitor in stimulus-response compatible (finger extension/flexion in vertical) or incompatible (horizontal) conditions.

MAIN OUTCOME MEASURE

Accuracy Index (AI) score on finger movement tracking tests.

RESULTS

With data collapsed across sexes, AI scores were significantly higher for control subjects compared with subjects with Parkinson's disease in compatible (P<.001) and incompatible (P<.001) positions. With data partitioned out across sexes, control men tracked significantly higher than men with Parkinson's disease in compatible (P=.004) and incompatible (P<.001) positions, but control women did not track significantly different from women with Parkinson's disease in either position. Control men tracked significantly higher than control women in compatible (P=.003) and incompatible (P=.001) positions, but men with Parkinson's disease did not track significantly different from women with Parkinson's disease in either position.

CONCLUSION

Parkinson's disease affects men and women disproportionately in manual tracking. Comparisons between subjects with Parkinson's disease and controls in spatial skill should include sex as a factor. More research is needed to confirm these findings.

Stimulus-response compatibility and psychological refractory period effects: implications for response selection

The purpose of this paper was to provide insight into the nature of response selection by reviewing the literature on stimulus-response compatibility (SRC) effects and the psychological refractory period (PRP) effect individually and jointly. The empirical findings and theoretical explanations of SRC effects that have been studied within a single-task context suggest that there are two response-selection routes-automatic activation and intentional translation. In contrast, all major PRP models reviewed in this paper have treated response selection as a single processing stage. In particular, the response-selection bottleneck (RSB) model assumes that the processing of Task 1 and Task 2 comprises two separate streams and that the PRP effect is due to a bottleneck located at response selection. Yet, considerable evidence from studies of SRC in the PRP paradigm shows that the processing of the two tasks is more interactive than is suggested by the RSB model and by most other models of the PRP effect. The major implication drawn from the studies of SRC effects in the PRP context is that response activation is a distinct process from final response selection. Response activation is based on both long-term and short-term task-defined S-R associations and occurs automatically and in parallel for the two tasks. The final response selection is an intentional act required even for highly compatible and practiced tasks and is restricted to processing one task at a time. Investigations of SRC effects and response-selection variables in dual-task contexts should be conducted more systematically because they provide significant insight into the nature of response-selection mechanisms.

Influences of different combinations of conceptual, perceptual, and structural similarity on stimulus-response compatibility

This study evaluated the hypothesis that an increase in set-level stimulus-response compatibility produces facilitation for congruent mappings and interference for incongruent mappings. The degree of set-level compatibility was manipulated by varying combinations of conceptual, perceptual, and structural similarity. Experiment 1 varied perceptual similarity, by combining two stimulus codes (spatial, verbal) with two response modalities (manual, vocal) for orthogonal spatial dimensions, which have structural similarity. The element-level mapping effect did not vary as a function of the code-modality relation, in contrast to findings obtained with parallel spatial dimensions, which also have conceptual similarity. Experiment 2 manipulated combinations of conceptual and perceptual similarity by combining vertical and horizontal stimulus and response orientations, using verbal or spatial stimuli and vocal responses. The element-level mapping effect was larger for parallel than orthogonal orientations, with congruent mappings showing facilitation and incongruent mappings showing interference. The largest effect was facilitation for parallel orientations with the verbal-vocal set, consistent with the view that perceptual similarity contributes to performance primarily when responding with the identity of the stimulus. Our results indicate that conceptual similarity, but not perceptual similarity, produces the facilitation/interference pattern suggestive of automatic activation of the corresponding response regardless of mapping.

Influence of operator orientation on relative organizational mapping and spatial compatibility

Following up on a study by Worringham and Beringer (1989) that examined the influence of operator orientation on visual-motor performance, Experiment 1 employed a choice reaction time paradigm in which participants had to make rapid, discrete movements with a lever in response to a discrete stimulus. In Experiment 2, participants had to synchronize rhythmic movements with an oscillating visual display. Operator orientation with respect to stimulus display and response array locations was varied to examine the influence of global spatial relations. Display orientation was varied to examine the influence of spatial configuration. Mapping rules were varied to examine the effects of spatial mapping. In Experiment 1, the spatial mapping that yielded faster responses was dependent upon the stimulus display-response array configuration and the global relation. Under a parallel configuration, participants appeared to code the spatial aspects of the stimulus display and response in a manner that was unaffected by the global spatial relation. Under an orthogonal configuration, spatial mapping effects were dependent upon the global relation. In Experiment 2, the global spatial relation did not have an impact on the uniformity of co-ordination under different configuration or mapping conditions. Spatial configuration influenced whether or not differences between spatial mapping rules emerged. Together, the results speak to the relative nature of stimulus-response coding that underlie compatibility phenomena. In addition, the results have potential importance for the design of human-machine systems that allow flexibility in operator orientation.

Deconstructing Marilyn: robust effects of face contexts on stimulus-response compatibility

Hommel and Lippa (1995) found a left-right spatial compatibility effect with respect to a background context of Marilyn Monroe's face, rotated 90 degrees clockwise or counterclockwise from upright, when subjects responded to up or down stimuli by pressing a left or a right key. They interpreted their results as providing evidence for object-based coding of stimulus location. We conducted four experiments in order to evaluate the reliability of this face context effect, to control for possible artifacts and evaluate alternative explanations, and to establish generalizability to other face contexts. This was accomplished by using not only the original photograph, but also a mirror-reversed image, chimeric faces composed from the left or the right sides of the original photograph, an outline drawing face, and a circle with markings for facial features. Our results were much stronger than those of Hommel and Lippa, and the face context effect was found for all of the face variations. Our experiments also provided evidence to suggest that asymmetric coding of the up and down locations contributes to performance in the face context as well.

Processing irrelevant location information: practice and transfer effects in choice-reaction tasks

Left or right keypresses to a relevant stimulus dimension are faster when the stimulus location, although irrelevant, corresponds with that of the response than when it does not. This phenomenon, called the Simon effect, persisted across 1,800 trials of practice, although its magnitude was reduced. Practice with the relevant stimulus dimension presented at a centered location had little influence on the magnitude of the Simon effect when irrelevant location was varied subsequently, and practice with location irrelevant prior to performing with location relevant slowed responses. After practice responding to stimulus location with an incompatible spatial mapping, the Simon effect was reversed (i.e., responses were slower when stimulus location corresponded with response location) when location was made irrelevant. When the response keys were labeled according to the relevant stimulus dimension (the Hedge and Marsh [1975] task variation), this reversal from practice with a spatially incompatible mapping was found for both the congruent and the incongruent relevant stimulus-response mappings. Thus, task-defined associations between stimulus location and response location affect performance when location is changed from relevant to irrelevant, apparently through producing automatic activation of the previously associated response.

Tracking control in the nonparetic hand of subjects with stroke

OBJECTIVE

To examine in subjects with stroke using their nonparetic side how different levels of stimulus-response (S-R) compatibility, which require different levels of information processing, affect manual tracking control.

DESIGN

Descriptive study comparing finger movement tracking performance under S-R-compatible and S-R-incompatible conditions between subjects with stroke and healthy controls. Four two-factor analysis of variance tests with one independent factor (group, gender, laterality, or order) and one repeated measures factor (position) comprised the data analysis.

SETTING

University-based research setting.

PATIENTS

Forty subjects with chronic stroke: 20 right hemiplegia (average age, 65.2+/-2.3 yrs); 20 left hemiplegia (average age, 68.6+/-2.3 yrs). Fifty-one healthy controls: 24 using nondominant hand (average age, 68.6+/-2.1 yrs); 27 using dominant hand (average age, 68.7+/-2.0 yrs). All were right-handed.

MAIN OUTCOME MEASURE

Tracking accuracy index (AI), based on root-mean-square error normalized to scale of each subject's tracking target.

RESULTS

In S-R-incompatible condition, AI of subjects with stroke was not significantly different from controls (F[1, 89]=1.73, p=.19). In S-R-compatible condition, AI of control subjects was significantly better than subjects with stroke (F[1, 89]=14.3, p=.0003).

CONCLUSION

Manual tracking is impaired in nonparetic hand of subjects with stroke, suggesting that information processing, distinctly separate from motor weakness, may be an underestimated problem impairing controlled movements in individuals with stroke.

Spatial stimulus-response compatibility in callosotomy patients and subjects with callosal agenesis

Subjects with partial or complete defects of the corpus callosum, either congenital or acquired, performed a choice reaction time (RT) task involving a right or left key-press response to a light presented at random in the right or left hemifield. Like normal subjects, all of them exhibited two additive effects typical of these tasks: the spatial stimulus-response compatibility effect (faster RT for stimuli and responses matched for side), and the hand placement effect (longer RT for responses performed with crossed hands). Two subjects with a complete callosal defect, one acquired and the other congenital, showed a third effect, not present in normal subjects, consisting of a marked advantage for RT of responses with hand anatomically ipsilateral to the stimulus, independent of both stimulus-response compatibility and hand placement. These findings can be interpreted according to a hierarchical model of information processing assuming that, in the absence of the corpus callosum, the matching of the mental codes for the stimulus and response sets takes place solely in the hemisphere receiving the stimulus, with a subsequent rapid-intrahemispheric or slow-interhemispheric transmission of the response command to the appropriate motor centers.

Evaluation of mental representation for same and mixed compatibility assignments

In most studies of stimulus-response (S-R) compatibility, assignments within a set are either compatible or incompatible for all S-R combinations. The present study provided an extension of previous research by examining the situations with same or mixed S-R assignments for pairs of subsets from a four-choice spatial precuing task. Assignments of stimuli to responses for the subsets could be same (both subsets assigned compatibility or both assigned incompatibility) or mixed (one subset assigned compatibility and one subset assigned incompatibility). A precue stimulus provided advanced information about which subset, and thus which assignment, would be required for responding on each trial. Experiment 1 had four visual stimuli assigned to four response locations, whereas Experiment 2 had the four visual stimuli assigned to only two response locations. For both experiments, the analyses revealed similar patterns of reaction times, with reaction times slower in the mixed condition than in the same condition. Moreover, the reaction times for the compatible assignments in the mixed sets were slowed more than the incompatible ones in those sets. The nonprecued subset influenced the S-R translation processes, indicating that the nonprecued subset was part of the mental representation upon which subjects were making decisions.

Stimulus-response compatibility effects in a manual tracking task

The purpose of this study was to determine whether there are stimulus-response (S-R) compatibility effects in a manual tracking task for male and female subjects of different ages. 20 healthy men and 20 healthy women in each of three different age groups (20 to 39, 40 to 59, and 60 to 79 years) participated (total N = 120). Subjects performed extension and flexion movements of the index finger metacarpophalangeal joint to track a computer-screen cursor along a target sine wave. The hand and forearm were positioned so that the finger movement was either vertical or horizontal, and the computer monitor was positioned so that the voluntary cursor movement was either vertical or horizontal. Each subject performed four different tracking tests corresponding to the four different ensembles of hand-forearm position and monitor position. There were significant differences in tracking performance between test ensembles in both women and men aged 60 to 79 years, and the compatible ensembles showed the superior performance. The results suggest that S-R compatibility effects exist in elderly women and elderly men performing a finger-movement tracking task, and these effects are consistent with impaired information processing in elderly persons. More research is needed on how S-R compatibility affects performance in persons with cerebral lesions.

A Forthcoming Key Press Can Be Selected While Earlier Ones Are Executed

The possibility that a key press can be selected during execution of earlier key presses and the resulting pattern of interferences were investigated in this study. Subjects (N equals 26) were required to press a series of keys, determined in advance, before they pressed a stimulus-dependent key. Response selection demands were manipulated by using spatially compatible and incompatible SndashR mappings because S-R compatibility is well known to not disappear with practice. The longer time needed to select an incompatible key vanished when the choice key was preceded by two or four predetermined key presses. Only early in practice did the time to press the first and the choice key in a three-key sequence exhibit part of the compatibility effect. With limited practice, concurrent preparation in the three-key sequence was relatively slow and took longer than the time required for executing the fixed keys. These findings suggest that processes involved in execution are not affected by concurrent response selection and that one of the effects of practicing movement sequences is that later movements can be selected while earlier ones are being executed. This need not affect execution rate. Therefore, different degrees of concurrent processing are not always reflected in reduced execution rates.

Stimulus-response compatibility for vertically oriented stimuli and horizontally oriented responses: evidence for spatial coding

It has previously been shown that, when stimuli positioned above or below a central fixation point ("up" and "down" stimuli) are assigned to left and right responses, the stimulus-response mapping up-left/down-right is more compatible than the mapping up-right/down-left for responses executed by the left hand in the left hemispace, but this relation is reversed for responses executed by the right hand in the right hemispace. In Experiment 1, each hand responded at locations in both hemispaces to dissociate the influence of hand identity from response location, and response location was found to be the determinant of relative compatibility. In Experiment 2 responses were made at the sagittal midline, and an inactive response switch was placed to the left or right to induce coding of the active switch as right or left, respectively. This manipulation of relative location had an effect similar to, although of lesser magnitude than, that produced by physically changing location of the response switch in Experiment 1. It is argued that these results are counter to predictions of a movement-preference account and consistent with the view that spatial coding underlies compatibility effects for orthogonally oriented stimulus and response sets.

Cross-modal compatibility effects with visual-spatial and auditory-verbal stimulus and response sets

Within the visual-spatial and auditory-verbal modalities, reaction times to a stimulus have been shown to be faster if salient features of the stimulus and response sets correspond than if they do not. Accounts that attribute such stimulus-response compatibility effects to general translation processes predict that similar effects should occur for cross-modal stimulus and response sets. To test this prediction, three experiments were conducted examining four-choice reactions with (1) visual spatial-location stimuli assigned to speech responses, (2) speech stimuli assigned to keypress responses, and (3) symbolic visual stimuli assigned to speech responses. In all the experiments, responses were faster when correspondence between salient features of the stimulus and response sets was maintained, demonstrating that similar principles of translation operate both within and across modalities.