Inhibitory and facilitatory effects of cue onset and offset

Attentional Orienting in Front and Rear Spaces in a Virtual Reality Discrimination Task

Recent studies on covert attention suggested that the visual processing of information in front of us is different, depending on whether the information is present in front of us or if it is a reflection of information behind us (mirror information). This difference in processing suggests that we have different processes for directing our attention to objects in front of us (front space) or behind us (rear space). In this study, we investigated the effects of attentional orienting in front and rear space consecutive of visual or auditory endogenous cues. Twenty-one participants performed a modified version of the Posner paradigm in virtual reality during a spaceship discrimination task. An eye tracker integrated into the virtual reality headset was used to make sure that the participants did not move their eyes and used their covert attention. The results show that informative cues produced faster response times than non-informative cues but no impact on target identification was observed. In addition, we observed faster response times when the target occurred in front space rather than in rear space. These results are consistent with an orienting cognitive process differentiation in the front and rear spaces. Several explanations are discussed. No effect was found on subjects’ eye movements, suggesting that participants did not use their overt attention to improve task performance.

The Effect of Ratio of Changing to Static Stimuli on the Attentional Capture

Studies have shown that appearing or disappearing objects attract more attention than static objects. This study examined the modulation of attention attracted by transient signals by systematically manipulating the ratio of changing (appearing/disappearing) to static stimuli. The results revealed that the effect of transient stimuli in attracting attention was diminished by simultaneously appearing (disappearing) peripheral stimuli and that the position where nothing was presented (the remaining stimulus) attracted attention when the number of appearing (disappearing) peripheral stimuli was increased. These findings suggest that the sudden change does not always capture attention, and whether changed things are attended or unchanged things are attended is determined depending on the proportion of things that change and do not change.

The effect of offset cues on saccade programming and covert attention

Salient peripheral events trigger fast, “exogenous” covert orienting. The influential premotor theory of attention argues that covert orienting of attention depends upon planned but unexecuted eye-movements. One problem with this theory is that salient peripheral events, such as offsets, appear to summon attention when used to measure covert attention (e.g., the Posner cueing task) but appear not to elicit oculomotor preparation in tasks that require overt orienting (e.g., the remote distractor paradigm). Here, we examined the effects of peripheral offsets on covert attention and saccade preparation. Experiment 1 suggested that transient offsets summoned attention in a manual detection task without triggering motor preparation planning in a saccadic localisation task, although there were a high proportion of saccadic capture errors on “no-target” trials, where a cue was presented but no target appeared. In Experiment 2, “no-target” trials were removed. Here, transient offsets produced both attentional facilitation and faster saccadic responses on valid cue trials. A third experiment showed that the permanent disappearance of an object also elicited attentional facilitation and faster saccadic reaction times. These experiments demonstrate that offsets trigger both saccade programming and covert attentional orienting, consistent with the idea that exogenous, covert orienting is tightly coupled with oculomotor activation. The finding that no-go trials attenuates oculomotor priming effects offers a way to reconcile the current findings with previous claims of a dissociation between covert attention and oculomotor control in paradigms that utilise a high proportion of catch trials.

Facilitation and inhibition caused by the orienting of attention in propositional reasoning tasks

In an attempt to study the orienting of attention in reasoning, we developed a set of propositional reasoning tasks structurally similar to Posner's (1980) spatial cueing paradigm, widely used to study the orienting of attention in perceptual tasks. We cued the representation in working memory of a reasoning premise, observing whether inferences drawn using that premise or a different, uncued one were facilitated, hindered, or unaffected. The results of Experiments 1a, 1b, 1c, and 1d, using semantically (1a–1c) or statistically (1d) informative cues, showed a robust, long-lasting facilitation for drawing inferences from the cued rule. In Experiment 2, using uninformative cues, inferences from the cued rule were facilitated with a short stimulus onset asynchrony (SOA), whereas they were delayed when the SOA was longer, an effect that is similar to the “inhibition of return” (IOR) in perceptual tasks. Experiment 3 used uninformative cues, three different SOAs, and inferential rules with disjunctive antecedents, replicating the IOR-like effect with the long SOAs and, at the short SOA, finding evidence of a gradient-like behaviour of the facilitation effect. Our findings show qualitative similarities to some effects typically observed in the orienting of visual attention, although the tasks did not involve spatial orienting.

Decomposing mechanisms of abnormal saccade generation in schizophrenia patients: Contributions of volitional initiation, motor preparation, and fixation release

Clinical and theoretical models suggest deficient volitional initiation of action in schizophrenia patients. Recent research provided an experimental model of testing this assumption using saccade tasks. However, inconsistent findings necessitate a specification of conditions on which the deficit may occur. The present study sought to detect mechanisms that may contribute to poor performance. Sixteen schizophrenia patients and 16 healthy control participants performed visually guided and two types of volitional saccade tasks. All tasks varied as to whether the initial fixation stimulus disappeared (fixation stimulus offset) or continued during saccade initiation, and whether a direction cue allowed motor preparation of the specific saccade. Saccade latencies of the two groups were differentially affected by task type, fixation stimulus offset, and cueing, suggesting abnormal volitional saccade generation, fixation release, and motor preparation in schizophrenia. However, substantial performance deficits may only occur if all affected processes are required in a task.

How to learn places without spatial concepts: Does the what-and-where reaction time system in children regulate learning during stimulus repetition?

We investigated the role of repetition for place learning in children although the acquisition of organizing spatial concepts is often seen as more essential. In a reaction-time accuracy task, 7- and 9-year-old children were presented with a randomized sequence of objects-in-places. In a novelty condition (NC), memory sets in different colors were presented, while in a repetition condition (RC), the identical memory set was tested several times. Shape memory deteriorated more than place memory in the NC, but also stayed superior to place memory when both improved in the RC. False alarms occurred for objects and places in the same way in 7-year-olds in the NC, but were negligible for 9-year-olds. In contrast, false alarms in the RC occurred in both age groups mainly for place memory. The Common Region Test (CRT) predicted reaction times only in the novelty condition, indicating use of spatial concepts. Importantly, reaction times for shapes were faster than for places at the beginning of the experiment but slowed down thereafter, while reaction times for places were slow at the beginning of the experiment but accelerated considerably thereafter. False alarms and regulation of reaction times indicated that repetition facilitated true abstraction of information leading to place learning without spatial concepts.

Attentional capture by object appearance and disappearance

In two experiments we examined whether the appearance of a new object has attentional priority over disappearance. Previous failures to show differences are possibly due to onsets and offsets always being presented as a sole visual transient. Rather than presenting each alone, we presented onset and offset singletons simultaneously with a display-wide luminance transient in order to force each to compete with other visual events. Results from Experiment 1 showed that targets associated with onsets accrued a reaction time benefit whilst targets associated with offsets did not. Experiment 2 showed that onsets attracted attention even when observers were attentionally set to look for offset. By contrast, offsets needed a relevant attentional set in order to attract attention. We argue that the appearance of an object has attentional priority over disappearance.

Left visual neglect: is the disengage deficit space- or object-based?

Attention can be directed to spatial locations or to objects in space. Patients with left unilateral spatial neglect are slow to respond to a left-sided target when it is preceded by a right-sided "invalid" cue, particularly at short cue-target intervals, suggesting an impairment in disengaging attention from the right side in order to orient it leftward. We wondered whether this deficit is purely spatial, or it is influenced by the presence of a right-sided visual object. To answer this question, we tested 10 right brain-damaged patients with chronic left-neglect and 41 control participants on a cued response time (RT) detection task in which targets could appear in either of two lateral boxes. In different conditions, non-informative peripheral cues either consisted in the brightening of the contour of one lateral box (onset cue condition), or in the complete disappearance of one lateral box (offset cue condition). The target followed the cue at different stimulus-onset asynchronies (SOAs). If the disengagement deficit (DD) is purely space-based, then it should not vary across the two cueing conditions. With onset cues, patients showed a typical DD at short SOAs. With offset cues, however, the DD disappeared. Thus, patients did not show any DD when there was no object from which attention must be disengaged. These findings indicate that the attentional bias in left-neglect does not concern spatial locations per se, but visual objects in space.

The role of attention in the occurrence of the affordance effect

It has been demonstrated that visual objects activate responses spatially corresponding to the orientation (left or right) of their graspable parts. To investigate the role of attention orienting in the generation of this effect, which we will refer to as affordance effect, we ran three experiments in which the target stimulus could either correspond or not with a dynamic event capturing attention. Participants were required to press a left or right key according to the vertical orientation (upward or inverted) of objects presented with their handles oriented to the right or to the left. In Experiments 1 and 2, the objects were located above or below fixation, while in Experiment 3, to assess the contemporary presence of the affordance and Simon effects, the objects were located to the left or right of fixation. The results showed that while the affordance effect, when evident, was always relative to the target object, irrespective of its attentional capturing properties, the Simon effect occurred relative to the event capturing attention. These findings suggest that automatic and controlled processes of visual attention may play a differential role in the occurrence of the two effects.

Better late than never: how onsets and offsets influence prior entry and exit

The three experiments presented in the paper examine visual prior entry (determining which of two stimuli appeared first) and prior exit (determining which of two stimuli disappeared first) effects with a temporal order judgment (TOJ) task. In addition to using onset and offset targets, the preceding cues also consisted of either onset or offset stimuli. Typical, and equivalent, prior entry effects were found when either onset or offset cues preceded the onset targets. Unexpectedly large prior exit effects where found with the offset targets, with offset cues producing greater capture effects than onset cues. These findings are consistent with the notion that more attention is allocated to searching the visual field when targets are more difficult to find. In addition, the results indicate that attentional control settings may be more likely to occur with more difficult searches. In addition, these findings demonstrate that TOJ tasks provide extremely precise measures of the allocation of attention and are very sensitive to a range of task manipulations.

Displaywide visual features associated with a search display’s appearance can mediate attentional capture

Whether or not the capture of visual attention is driven solely by the salience of an attention-capturing stimulus or mediated by top-down control has been a point of contention since Folk, Remington, and Johnston (1992) introduced their contingent involuntary orienting hypothesis, which states that the capture of attention by a salient stimulus depends on its relevance to a feature distinguishing the target from nontargets. Gibson and Kelsey (1998) extended Folk et al.'s (1992) hypothesis by demonstrating that features associated with the appearance of the target display also mediate capture. Although similar to Folk et al. (1992), Gibson and Kelsey's displaywide contingent orienting hypothesis makes it difficult to demonstrate stimulus-driven capture, because an observer must always use some perceptible feature as a signal of the target display's appearance; hence, such features could always be mediating capture. The present article reviews and applies the logic of Gibson and Kelsey's and Folk et al.'s (1992) hypotheses to experiments from the attentional capture literature, and assesses whether previously reported capture effects were mediated by top-down attentional control. It concludes that these capture effects were not stimulus-driven.

Aging and temporal patterns of inhibition of return

Inhibition of return (IOR), an inhibitory component of spatial attention that is thought to bias visual search toward novel locations, is considered relatively well preserved with normal aging. We conducted two experiments to assess age-related changes in the temporal pattern of IOR. Inhibitory effects, which were strongly reflected in the performance of both younger adults (ages 18-34 years) and older adults (ages 60-79 years), diminished over a period of 5 s. The time point at which IOR began to diminish was delayed by approximately 1 s for older adults compared with younger adults; this pattern was observed on both a target detection task (Experiment 1) and a color discrimination task (Experiment 2). The finding that timing characteristics of IOR are altered by normal aging has potential implications for the manner in which inhibition aids search performance.

Reorienting attention and inhibition of return

In experiments examining inhibition of return (IOR), it is common practice to present a second cue at fixation during the cue-target interval. The purpose of this fixation cue is to reorient attention away from the cued location to ensure that the facilitative effects of spatial attention do not obscure IOR. However, despite their frequent use, relatively little is known about the relationship between fixation cues and IOR. In the present experiments, we examined the role of fixation cues by manipulating their presence in tasks that either did or did not require target identification. When the participants were required to either detect (Experiment 1A) or localize (Experiment 2A) a target, the magnitude of IOR was unaffected by the presence of a fixation cue. In contrast, when the participants were required to identify a target (Experiments 1B, 2B, and 3), IOR was observed only when a fixation cue was presented. This result was obtained regardless of the type of response that was required (two-alternative forced choice or go/no go). The effectiveness of the fixation cue in revealing IOR in these tasks is consistent with its putative role in reorienting attention away from the cued location.

The effects of anxiety upon attention allocation to affective stimuli

Pictures of emotionally aversive, neutral, and pleasant scenes were presented for 500 ms, followed by a probe presented in the same location (valid trials) or an alternate location (invalid trials) as the picture. Response-times to the probes were recorded in low (N=20) and high (N=27) trait anxious participants. Results revealed an overall negative cue validity effect of shorter reaction times (RTs) on invalid than valid trials, suggestive of an inhibition of return effect. Moreover, high trait anxious females showed a reduced negative cue validity effect for aversive pictures in comparison with neutral and pleasant pictures, suggestive of selective interference by the unpleasant material. By contrast, low trait anxious females showed an enhanced negative cue validity effect for aversive pictures relative to neutral and pleasant pictures, suggestive of attentional avoidance of the aversive content. The emotional content of picture cues did not significantly affect RTs in males, regardless of anxiety status. The results suggest that biased attention processes for aversive stimuli may contribute to the greater female propensity for anxiety disorders.

Time-dependent effects of discrete spatial cues on the planning of directed movements

The degree of preparation of a motor response varies with the information available regarding the response that will need to be executed and with the time provided to process that information. In experiment 1 we investigated the time-course of processing the information specified by discrete spatial cues regarding the upcoming target of directed movements. For this purpose we varied the number of cues that indicated the possible locations of the target and the duration of the cue period preceding the target. The results showed that the effects of processing the information provided by the cues developed progressively and stabilized after 0.2 s. In addition, the level of motor preparation reached was a function of number of cues. However, the effect of number of cues occurred even in the no cue period condition, i.e. when subjects could not have benefited from the information provided by the cues to prepare the response. Further analyses suggested the hypothesis that, in the no cue period condition, the effect of number of cues resulted from the cues acting as distractors (i.e., interference) whereas, with longer cue periods, the effect resulted from the motor preparatory process (i.e., facilitation). This hypothesis was tested in experiment 2 where the number of cues and the number of distractors were varied inversely. Cues and distractors were the same type of stimuli and differed only in their relation to the time of presentation of the target. Subjects performed in a directed response task and in a control detection task. It was predicted that the facilitatory effect of the cues and the interference effect of the distractors on the planning of the directed response would oppose each other and produce a non-monotonic change of RT across conditions. The results conformed to the prediction and, therefore, supported the hypothesis of independent effects of facilitation and interference. In addition, we found that the pattern of RT across conditions in the detection task differed radically with that in the directed response task. This result indicates that the time-dependent effects of cues and distractors are contingent on the type of motor response required in the task, and, in particular on the spatial requirement on the motor response.

Pro-saccades and anti-saccades to onset and offset targets

Pro- and anti-saccades made to either onset or offset targets were examined to determine which of (1) changes in luminance or (2) the appearance of new peripheral objects, is more important in the reflexive generation of pro-saccades. In two experiments, pro-saccades had faster reaction times than did anti-saccades, but the difference was much greater for onset targets than offset targets (both with white targets on black backgrounds and black targets on white backgrounds). These findings suggest that there is a continuum of "prepotentness" in the oculomotor system with new peripheral objects being especially effective in generating reflexive pro-saccades.

Examining inhibition of return with onset and offset cues in the multiple-cuing paradigm

Three experiments examined inhibition of return (IOR) with onset and offset cues in a multiple-cuing paradigm. In the first two experiments, five sequential cues either appeared and remained present (onset cues) or disappeared and remained absent (offset cues). In the third experiment, the cues were either onset cues or on-off cues (appeared and then disappeared quickly after). With placeholders present, onset and offset cues produced similar declines in IOR from the most recently cued location (Experiment 1). In contrast, onset cues produced overall more IOR than on-off cues (Experiment 3). With placeholders absent (Experiment 2), no IOR was found for either onset or offset cues. The results suggest that even in a complex multiple-cuing paradigm, onsets and offsets are treated similarly by the attentional system. Furthermore, it appears that onset cues are easier to encode as previously searched than on-off cues, suggesting a role of working memory in IOR. Finally, when multiple locations are cued sequentially by onsets and offsets they must be marked by placeholders for inhibition to occur.

Visual salience in the change detection paradigm: the special role of object onset

The relative efficacy with which appearance of a new object orients visual attention was investigated. At issue is whether the visual system treats onset as being of particular importance or only 1 of a number of stimulus events equally likely to summon attention. Using the 1-shot change detection paradigm, the authors compared detectability of new objects with changes occurring at already present objects--luminance change, color change, and object offset. Results showed that appearance of a new object was less susceptible to change blindness than changes that old objects could undergo. The authors also investigated whether it is onset per se that leads to enhanced detectability or onset of an object representation. Results showed that the onset advantage was eliminated for onsets that did not correspond with the appearance of a new object. These findings suggest that the visual system is particularly sensitive to the onset of a new object.

Revealing effects of noninformative spatial cues: An EEG study of inhibition of return

Simple responses to noninformatively cued spatial stimuli can be delayed whenever a cue has been briefly presented at the location of the subsequent target. This phenomenon (inhibition of return) might be due to a mechanism that inhibits irrelevant information. However, with sustained cues no inhibition is observed. It has been hypothesised that in the latter, task inhibition is masked by an excitation process. ERP measures support the inhibition-excitation account: (a) P1 suppression, assumed to reflect inhibition, was observed for all targets presented at a cued location. (b) A later negative component (Nd250) was increased with sustained cues, and hence might reflect the excitation process. (c) A negative component at right parietal electrode sites (Nd310) appeared only when inhibition of return was observed. A second study confirmed the link between these ERP components and mechanisms involved in inhibition of return.

The role of temporal and spatial factors in the covert orienting of visual attention tasks

There is a biphasic pattern in response times to peripheral uninformative cues, with faster responses to targets in cued locations when the stimulus onset asynchrony (SOA) is under 300 ms and slower responses when it is over 300 ms. The effect has typically been attributed entirely to the SOA while ignoring other aspects of the cues (duration, spatial configuration). To examine these other factors, along with SOA, the present experiments included manipulations of SOA (50, 100, 200, 400, 800 ms), inter-stimulus interval (ISI; 0, 50, 100, 150, 200, 300, 350, 400, 500, 600, 700, and 750 ms), and whether or not the cue and target overlap in the same space. The results indicate that cueing effects depend on the combination of cue duration, ISI, SOA, and the spatial configuration of the cues and targets. Three factors are used to explain these time course results.

Experimental context modulates warning signal effects

Previous studies have shown that saccadic eye responses but not manual responses were sensitive to the kind of warning signal used, with visual onsets producing longer saccadic latencies compared to visual offsets. The aim of the present study was to determine the effects of distinct warning signals on manual latencies and to test the premise that the onset interference, in fact, does not occur for manual responses. A second objective was to determine if the magnitude of the warning effects could be modulated by contextual procedures. Three experimental conditions based on the kind of warning signal used (visual onset, visual offset and auditory warning) were run in two different contexts (blocked and non-blocked). Eighteen participants were asked to respond to the imperative stimulus that would occur some milliseconds (0, 250, 500 or 750 ms) after the warning signal. The experiment consisted in three experimental sessions of 240 trials, where all the variables were counterbalanced. The data showed that visual onsets produced longer manual latencies than visual offsets in the non-blocked context (275 vs 261 ms; P < 0.001). This interference was obtained, however, only for short intervals between the warning and the stimulus, and was abolished when the blocked context was used (256 vs 255 ms; P = 0.789). These results are discussed in terms of bottom-up and top-down interactions, mainly those related to the role of attentional processing in cancelling out competitive interactions and suppressive influences of a distractor on the relevant stimulus.

Inhibition of return: A graphical meta-analysis of its time course and an empirical test of its temporal and spatial properties

Immediately after a stimulus appears in the visual field, there is often a short period of facilitated processing of stimuli at or near this location. This period is followed by one in which processing is impaired, rather than facilitated. This impairment has been termed inhibition of return (IOR). In the present study, the time course of this phenomenon was examined in two ways. (1) A graphical meta-analysis plotted the size of the effect as a function of the stimulus onset asynchrony (SOA) of the two stimuli. This analysis showed that IOR is impressively stable for SOAs of 300-1,600 msec. It also showed that the literature does not provide any clear sense of the duration of IOR. (2) An empirical approach was, therefore, taken to fill this gap in our knowledge of IOR. In three experiments, IOR was tested using SOAs between 600 and 4,200 msec. IOR was robust for approximately 3 sec and appeared to taper off after this point; the observed duration varied somewhat as a function of the testing conditions. In addition, for the first second, the degree of inhibition was inversely related to distance of the target from the original stimulus, but for the next 2 sec this spatial distribution was not observed. Theories of the mechanisms and function of IOR must conform to these spatial and temporal properties.

Inhibition of return for target discriminations: the effect of repeating discriminated and irrelevant stimulus dimensions

Inhibition of return (IOR) refers to slowed reaction times when a target repeats in the same location as a preceding stimulus. In four experiments, the participants were presented with two successive stimuli, S1 and S2. In Experiments 1 and 2, the participants made a speeded discrimination of the identity or orientation of both S1 and S2 (Experiment 1) or of S2 only (Experiment 2). An IOR effect occurred for the repetition of stimulus location, but a facilitatory effect occurred if the stimulus remained unchanged or if an overt response was repeated. In Experiments 3 and 4, the participants localized S1 and S2 (Experiment 3) or S2 only (Experiment 4) to the left or right of center. In this case, repeating the same stimulus had no effect: IOR occurred any time stimulus location repeated. These results demonstrate that the expression of IOR is modulated by the repetition of a target object, but only when the task requires the discrimination of that object; when no discrimination is required, IOR is unaffected.

Anxiety and attention to threatening pictures

Previous research using attentional search tasks has revealed an anxiety-related bias favouring attention to threatening words when they are presented simultaneously with emotionally neutral words. In Experiment 1, using a similar task, a related effect was found here with emotionally threatening pictures. When pictures were used as location cues in a second experiment, high-trait anxious individuals were slower than less anxious controls when responding to targets requiring attentional disengagement from threat, and they were slower in general with pictures judged to be highly threatening. In a third experiment using the same task but with a longer cue exposure, a related disengagement difficulty occurred across both groups, although the more general slowing with severe threat was again confined to the anxious group. We conclude that attentional bias involves both a specific difficulty in disengaging attention from the location of any threat and a more general interference effect that is related to threat level.

The presence of a nonresponding effector increases inhibition of return

Inhibition of return (IOR) refers to the performance disadvantage for targets presented at an exogenously cued location, relative to an uncued location, at relatively long cue-target onset asynchronies. In this experiment, we investigated the influence on IOR of a nonresponding effector (i.e., the index finger of the nonresponding hand) placed on a response key in a simple-RT task. With peripheral cues and targets, IOR and spatial stimulus-response compatibility effects were larger when the nonresponding hand was placed on a response key. IOR--the slowed responding to go signals at the cued location--was accompanied by a lower false alarm rate when no-go signals were presented there. These findings provide direct evidence for a motoric component to IOR wherein some portion of the inhibition is observed as a criterion shift against responding to the cued location.