The role of affordances in inhibition of return

Inhibition of return (IOR) is a response delay that occurs when the target is preceded by an irrelevant stimulus (cue) at the same location. IOR can be object based, as well as location based. The aim of the present study was to investigate the role of the pragmatic features of a visually presented object in causing IOR. Two experiments were carried out using different objects as stimuli, for which the graspable part (affordance) was clearly defined. The presentation of a whole object, with the part commonly used to grasp it located below, served as a cue. The presentation of either the graspable or the ungraspable part of the cued or uncued object served as the target Results showed that responses were slower when the graspable part was shown in the cued location than when the ungraspable part was shown in the same location. The effect was apparently linked to the kind of action necessary to grasp an object.     

The role of the fixation location in inhibition of return.

Experiments that have examined inhibition of return (IOR) have typically used trial sequences in which attention is reoriented to a central fixation location between the presentation of the peripheral cue(s) and the target. In examining the role of the fixation location in IOR, three experiments were conducted in which an exogenous cue was used to reorient attention following a peripheral cue and before the appearance of a target. However, this cue occurred at either the traditional central fixation location or a nonfixated location. The results indicate that reorienting attention to a fixated location results in a significant reduction in the inhibitory effect. The results from the study suggest that IOR could serve as a mechanism that improves the efficiency of visual searches.     

Examining the role of the fixation cue in inhibition of return.

To clarify the role of the fixation cue in inhibition of return (IOR), the present study compared four conditions: fixation cue immediately after the peripheral cue, in the middle of the stimulus-onset asynchrony (SOA), immediately before the onset of the target, or no fixation cue. With a 200-ms SOA, less IOR was found when the fixation cue was either absent or occurred immediately after the peripheral cue. No differences between the four conditions were found with 400-ms and 800-ms SOAs. These findings suggest that there is a brief period of time in which attention cannot be withdrawn from the peripherally cued location. Once attention has been withdrawn from the peripherally cued location, IOR can be found at short SOAs.     

A direct assessment of the role of state and trait negative emotion in aggressive behavior

Affective priming of aggression was examined in groups low and high in trait negative emotionality (NEM) using a Buss aggression paradigm. Negative affect was induced by exposure to aversive air blasts during some intervals (threat) and not others (safe). Phasic negative affect was assessed using startle reflex potentiation, and tonic distress was indexed by startle sensitization. Participants delivered shocks faster during threat versus safe intervals, indicating that phasic distress primed aggression. Following initial exposure to air blasts, high NEM participants showed enhanced tonic distress and delivered persistently more intense shocks than low NEM participants. These findings indicate that sustained negative affect biases high stress-reactive individuals toward more intense acts of aggression, with phasic distress affecting the rapidity of aggressive response.     

The role of attention in the facilitation effect and another "inhibition of return"

The present study investigated how anticipation of a target's appearance affects human attention to gaze cues provided by a schematic face. Subjects in a 'catch' group received a high number of 'catch' trials, in which no target stimulus appeared. Subjects in the control group did not receive any catch trials. As in previous studies, both groups showed a facilitation effect to the cued location during shorter stimulus onset asynchrony (SOA). In both groups, an analysis of eye movements confirmed that subjects' eyes remained on the fixation point, ruling out the possibility that the facilitation effect was due to shifting eye movements (saccades) as opposed to a shift in covert attention. But while the control group's response time (RT) decreased as SOA increased, the catch group's RT had a U-shaped pattern and the facilitation effect to the cued location was reversed at the longest SOA (1005 ms). These results suggest that subjects in the catch group disengaged their attention during long SOAs because they expected the trial to be a catch trial. This disengagement of attention during long SOAs results in a delay before attention could be re-focused to the previous location regardless of the cue validity ["IOR (inhibition of return)"-like-phenomenon]. Unlike the conventional IOR, we suggest that this "IOR"-like phenomenon caused by an unpredictive central gaze cue is likely to be mediated by an endogenous mechanism.     

Color-based inhibition of return

The inhibition of return of visual attention based on stimulus color was examined in three experiments. In the first experiment, a discrete trial paradigm showed that subjects were slower to detect a color patch if the color matched that of a patch presented earlier in the same location. Experiment 2 showed that the inhibition only occurs if a neutral, nontarget distractor color is presented between presentation of the initial color cue and the subsequent target patch—explaining the previous failures to detect the phenomenon. Experiment 3 extended the results to a different combination of colors. Taken together, the results have important implications for the processing of stimulus attributes such as spatial location and color, and for the conditions necessary for producing inhibition of return.     

Social inhibition of return

Responses to a target stimulus can be slower when it appears in the same rather than a different location to a previous event, an effect known as inhibition of return (IOR). Recently, it has been shown that when two people alternate responses to a target, one person’s responses are slower when they are directed to the same locations as their partner’s previous response. The present study sought to investigate this highly novel effect, which we term social IOR (SIOR), in relation to what is known of IOR in individuals performing alone. We found that only a real conspecific can induce SIOR in another person, whereas an animated conspecific cannot. Additionally, SIOR emerges at locations to which a conspecific has been inferred to respond, even when direct observation of his/her responses is prevented. Finally, SIOR can be induced without the abrupt visual transients normally associated with the generation of IOR. These findings suggest that SIOR is the result of stronger activations of IOR mechanisms, or that it is subserved by entirely separate inhibitory processes.     

A short-lived face alert during inhibition of return

In the present study, we explored the role of faces in oculomotor inhibition of return (IOR) using a tightly controlled spatial cuing paradigm. We measured saccadic response latency to targets following peripheral cues that were either faces or objects of lesser sociobiological salience. A recurring influence from cue content was observed across numerous methodological variations. Faces versus other object cues briefly reduced saccade latencies toward subsequently presented targets, independently of attentional allocation and IOR. The results suggest a short-lived priming effect or social facilitation effect from the mere presence of a face. In the present study, we further showed that saccadic responses were unaffected by face versus nonface objects in double-cue presentations. Our findings indicate that peripheral face cues do not influence attentional orienting processes involved in IOR any differently from other objects in a tightly controlled oculomotor IOR paradigm.     

Unmasking the inhibition of return phenomenon

Conventional wisdom holds that a nonpredictive peripheral cue produces a biphasic response time (RT) pattern: early facilitation at the cued location, followed by an RT delay at that location. The latter effect is called inhibition of return (IOR). In two experiments, we report that IOR occurs at a cued location far earlier than was previously thought, and that it is distinct from attentional orienting. In Experiment 1, IOR was observed early (i.e., within 50 msec) at the cued location, when the cue predicted that a detection target would occur at another location. In Experiment 2, this early IOR effect was demonstrated to occur for target detection, but not for target identification. We conclude that previous failures to observe early IOR at a cued location may have been due to attention being directed to the cued location and thus “masking” IOR.     

The role of attentional set on attentional cueing and inhibition of return

When people know what critical feature will define a target for a block of trials, only cues that share a critical feature with targets will capture attention. This result is taken to mean that attentional control settings play a role in target identification. To examine the validity of the attentional control settings hypothesis while controlling for potential sensory artifacts, the first experiment compared conditions in which the critical target features were either blocked or randomized. The results indicated that all cues captured attention in the random conditions, but only cues that matched targets captured attention in the attentional set condition. The second experiment used the same two conditions to examine the effect of attentional set on inhibition of return (IOR). No differences were found between the blocked and random conditions, indicating that attentional set did not impact the IOR effects. Overall, the results indicate that (1) the previous findings of attentional set effects were not due to an artifact of the method, and (2) attentional set influences and early occurring attentional cueing effects but not later-occurring IOR effects.     

On the role of eye movements and saccade preparation in generating auditory inhibition of return.

In three experiments, listeners were required to either localize or identify the second of two successive sounds. The first sound (the cue) and the second sound (the target) could originate from either the same or different locations, and the interval between the onsets of the two sounds (Stimulus Onset Asynchrony, SOA) was varied. Sounds were presented out of visual range at 135 azimuth left or right. In Experiment 1, localization responses were made more quickly at 100 ms SOA when the target sounded from the same location as the cue (i.e., a facilitative effect), and at 700 ms SOA when the target and cue sounded from different locations (i.e., an inhibitory effect). In Experiments 2 and 3, listeners were required to monitor visual information presented directly in front of them at the same time as the auditory cue and target were presented behind them. These two experiments differed in that in order to perform the visual task accurately in Experiment 3, eye movements to visual stimuli were required. In both experiments, a transition from facilitation at a brief SOA to inhibition at a longer SOA was observed for the auditory task. Taken together these results suggest that location-based auditory IOR is not dependent on either eye movements or saccade programming to sound locations.     

Inhibition of return to an occluded object depends on expectation

Inhibition of return (IOR) is indexed by slower reaction times to targets presented at previously attended locations or objects. If a moving object is occluded, some studies find IOR, others do not. Four experiments examined whether this inconsistency hinges on the observer's expectation as to whether the object continues to exist at the end of its motion sequence. Results showed that observer expectation is a powerful determining factor: IOR occurs only if the observer expects the object to continue to exist. In contrast, if the object is not occluded, IOR occurs only if the object remains on view immediately before the target is presented. It was concluded that 2 factors, object continuity and observer expectation, mediate both location- and object-based IOR.     

Unmasking the inhibition of return phenomenon.

Conventional wisdom holds that a nonpredictive peripheral cue produces a biphasic response time (RT) pattern: early facilitation at the cued location, followed by an RT delay at that location. The latter effect is called inhibition of return (IOR). In two experiments, we report that IOR occurs at a cued location far earlier than was previously thought, and that it is distinct from attentional orienting. In Experiment 1, IOR was observed early (i.e., within 50 msec) at the cued location, when the cue predicted that a detection target would occur at another location. In Experiment 2, this early IOR effect was demonstrated to occur for target detection, but not for target identification. We conclude that previous failures to observe early IOR at a cued location may have been due to attention being directed to the cued location and thus "masking" IOR.     

Reconceptualizing inhibition of return as

Inhibition of return (IOR) is an effect on spatial attention whereby reaction times to a target presented at a location where a stimulus had recently been presented are increased, as opposed to when a target is presented at a new location. Despite early reports that habituation is not responsible for the IOR effect, the human cognitive literature provides indirect evidence in favor of the possibility. In addition, recent neurophysiological studies provide direct support for the idea that habituation is at least a contributing source for the IOR effect. The present article describes how habituation may account for the IOR effect and explores some of the predictions that this hypothesis suggests.     

Probing distractor inhibition in visual search: inhibition of return

The role of inhibition of return (IOR) in serial visual search was reinvestigated using R. Klein's (1988) paradigm of a search task followed by a probe-detection task. Probes were presented at either the location of a potentially inhibited search distractor or an empty location. No evidence of IOR was obtained when the search objects were removed after the search-task response. But when the search objects remained on, a pattern of effects similar to Klein's results emerged. However, when just the search-critical object parts were removed or when participants received immediate error feedback to prevent rechecking of the search objects, IOR effects were observed only when probes appeared equally likely at search array and empty locations. These results support the operation of object-based IOR in serial visual search, with IOR demonstrable only when rechecking is prevented (facilitating task switching) and monitoring for probes is not biased toward search objects.     

Location and shape in inhibition of return

Inhibition of return (IOR) is characterized by a delay in responding to a target preceded by an irrelevant stimulus (cue) at the same location, or, in other words, by a response delay when the same location is stimulated twice. It is not clear, however, if the same phenomenon is present when there is a repetition of a simple nonspatial attribute of the stimulus. The present study examines the repetition of shape. Six experiments were conducted. In Experiments 1, 2, 3, and 6 the stimuli were geometrical shapes, whereas in Experiments 4 and 5 letters were used. In Experiment 1 all the stimuli were presented at fixation, whereas in Experiments 2 to 6 they were presented in the periphery. In Experiments 2 and 3, location and shape of the cue and the target were independently manipulated in order to test independently inhibitory effects (IOR?) attributable to location repetition and shape repetition. Results showed an inhibitory effect for location and a much smaller inhibitory effect for shape. The latter was restricted to the cued location. Experiments 4 and 5 tested the possibility that inhibition caused by shape repetition is due to repetition blindness. Experiment 6 contrasted the presence or absence of a central neutral attractor in the delay interval between presentation of the cue and the target. Taken together the results seem to favor IOR as the basis for the inhibition caused by shape repetition.     

Object-based inhibition of return in static displays

After attention has been oriented to a location, inhibition mechanisms prevent the return of attention shortly afterward. This inhibition can be associated with an object in such a way that after cuing attention to the object, inhibition can move with the object to a new location. Recent research has noted that the object-based inhibition of return effect in moving displays is much smaller than the effect observed in static displays, and hence may be of little functional utility. However, we demonstrate that, on the contrary, the large effects observed in static displays are produced precisely because of the existence of object-based frames, which can be additive with location-based frames of reference.     

Long-term inhibition of return of attention

During search of the environment, the inhibition of the return (IOR) of attention to already-examined information ensures that the target will ultimately be detected. Until now, inhibition was assumed to support search of information during one processing episode. However, in some situations search may have to be completed long after it was begun. We therefore propose that inhibition can be associated with an episode encoded into memory such that later retrieval reinstates inhibitory processing and encourages examination of new information. In two experiments in which attention was drawn to face stimuli with an exogenous cue, we demonstrated for the first time the existence of long-term IOR. Interestingly, this was the case only for faces in the left visual field, perhaps because more efficient processing of faces in the right hemisphere than the left hemisphere results in richer, more retrievable memory representations.     

Vector averaging of inhibition of return

Observers detected targets presented 400 msec after a display containing one cue or two to four cues displayed simultaneously in randomly selected locations on a virtual circle around fixation. The cue arrangement was completely uninformative about the upcoming target’s location, and eye position was monitored to ensure that the participants maintained fixation between the cue and their manual detection response. Reflecting inhibition of return (IOR), there was a gradient of performance following single cues, with reaction time decreasing monotonically as the target’s angular distance from the cued direction increased. An equivalent gradient of IOR was found following multiple cues whose center of gravity fell outside the parafoveal region and, thus, whose net vector would activate an orienting response. Moreover, on these trials, whether or not the targeted location had been stimulated by a cue had little effect on this gradient. Finally, when the array of cues was balanced so that its center of gravity was at fixation, there was no IOR. These findings, which suggest that IOR is an aftermath of orienting elicited by the cue, are compatible with population coding of the entire cue (as a grouped array for multiple cues) as the generator of IOR.     

The role of spatial working memory in inhibition of return: evidence from divided attention tasks

Inhibition of return (IOR) refers to a bias against returning attention to a location that has been recently attended. In the present experiments, we examined the role of working memory in IOR by introducing secondary tasks (in the temporal interval between the cue and the target) that involved a working memory component. When the secondary task was nonspatial in nature (monitoring odd digits or adding digits), IOR was present, although overall reaction times were greater in the presence of the secondary task. When the task involved a spatial working memory load (remembering the directionality of arrows or the orientation of objects), IOR was eliminated. However, when the participants had incentive to process the directionality of an arrow but did not have to use any memory system, IOR persisted at peripheral locations. Overall, the results suggest that IOR is partially mediated by a spatial working memory system.