Irrelevant onsets cause inhibition of return regardless of attentional set

It is disputed whether onsets capture spatial attention either in a purely stimulus-driven fashion or only when they are contingent on one's attentional set. According to the latter assumption, interference from irrelevant onsets may result from nonspatial filtering costs. In the present study, we used inhibition of return (IOR) as a marker for spatial attention. IOR occurs mainly for locations that attention has visited before. Participants searched for a red object among white objects. An attentional set for redness was demonstrated by a spatial validity effect of red cues on response times. However, a stronger validity effect was found for irrelevant white onsets, which slowed responses when the onset contained a distractor, but speeded them when the onset contained a target. Most importantly, this onset benefit for targets turned into a deficit at longer SOAs, indicating IOR. We conclude that onset distractors capture spatial attention regardless of the observer's attentional set.     

The effects of implicit attentional learning and habituation on inhibition of return

In two experiments, the effects of implicit attentional learning and habituation on inhibition of return (IOR) were assessed. Experiment 1 consisted of an informative variant of the spatial cuing paradigm (Posner, 1980), with the target appearing most often at the location next to the cue. Short-term as well as long-term learning of the regularities could be observed. This learning took place even though the participants were not able to verbalize the learned information, suggesting that the learning was implicit. By spatially separating the effects of implicit learning and IOR, we demonstrated that the magnitude of IOR slightly decreased because of long-term implicit orienting. In Experiment 2, a noninformative variant of the spatial cuing paradigm, IOR was still found to decrease over the course of the experiment. This suggests that habituation due to the mere repeated initiation of IOR also affects the magnitude of the IOR. This theory is supported by the finding that IOR recovered after short breaks in Experiment 2. However, habituation presumably only played a secondary role in Experiment 1. In sum, IOR was abolished by neither implicit attentional learning nor habituation. Here, the finding that IOR is not easily replaced by implicitly learned orienting clearly indicates that IOR is a powerful, low-level mechanism. We discuss implications of these results for the debate on the function of IOR.     

Incidental learning of secondary attentional cueing

Subjects instructed to detect targets following moderately valid location cues started being presented at some point in the course of the experiment, without having been informed about it, with a color secondary cue on all invalidly cued trials. In Experiment 1 most subjects quickly learned to use the secondary cue, ending in latency cost being eliminated or even turned negative. The effect failed to manifest only when the secondary cue appeared outside the object serving as imperative cue. Experiment 2 showed that performance with a secondary cue differed significantly from the performance in two control conditions in which colors were not correlated with validity or were not presented at all. On the other hand, it resembled performance of subjects informed beforehand about the secondary cue. Awareness of the contingency as well as of its effect on behavior was probed by a post-test questionnaire. An effect of learning without awareness was not observed in Experiment 1, but was found in Experiment 3, where awareness was probed more shortly after the emergence of incidental learning. Conceivably, subjects first learn to use the contingencies implicitly, and only later do they become aware of the outcome of that learning. Apparently, the attentional system might incidentally learn contingencies detected while being engaged in another task and use them for orienting despite a partial conflict with the following as instructed endogenous cues.     

Probing attentional modulation of contextual cueing

The repetition of spatial layout implicitly facilitates visual search (contextual cueing effect; Chun & Jiang, 1998). Although a substantial number of studies have explored the mechanism underlying the contextual cueing effect, the manner in which contextual information guides spatial attention to a target location during a visual search remains unclear. We investigated the nature of attentional modulation by contextual cueing, using a hybrid paradigm of a visual search task and a probe dot detection task. In the case of a repeated spatial layout, detection of a probe dot was facilitated at a search target location and was inhibited at distractor locations relative to nonrepeated spatial layouts. Furthermore, these facilitatory and inhibitory effects possessed different learning properties across epochs (Experiment 1) and different time courses within a trial (Experiment 2). These results suggest that contextual cueing modulates attentional processing via both facilitation to the location of “to-be-attended” stimuli and inhibition to the locations of “to-be-ignored” stimuli.     

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 time course of attentional deployment in contextual cueing

The time course of attention is a major characteristic on which different types of attention diverge. In addition to explicit goals and salient stimuli, spatial attention is influenced by past experience. In contextual cueing, behaviorally relevant stimuli are more quickly found when they appear in a spatial context that has previously been encountered than when they appear in a new context. In this study, we investigated the time that it takes for contextual cueing to develop following the onset of search layout cues. In three experiments, participants searched for a T target in an array of Ls. Each array was consistently associated with a single target location. In a testing phase, we manipulated the stimulus onset asynchrony (SOA) between the repeated spatial layout and the search display. Contextual cueing was equivalent for a wide range of SOAs between 0 and 1,000 ms. The lack of an increase in contextual cueing with increasing cue durations suggests that as an implicit learning mechanism, contextual cueing cannot be effectively used until search begins.     

Effects of relevant and irrelevant color singletons on inhibition of return and attentional capture

We tested whether color singletons lead to saccadic and manual inhibition of return (IOR; i.e., slower responses at cued locations) and whether IOR depended on the relevance of the color singletons. The target display was preceded by a nonpredictive cue display. In three experiments, half of the cues were response-relevant, because participants had to perform a discrimination task at the cued location. With the exception of Experiment 2, none of the cue colors matched the target color. We observed saccadic IOR after color singletons, which was greater for slow than for fast responses. Furthermore, when the relevant cue color matched the target color, we observed attentional capture (i.e., faster responses at cued locations) with rapid responses, but IOR with slower responses, which provides evidence for attentional deallocation. When the cue display was completely response-irrelevant in two additional experiments, we did not find evidence for IOR. Instead, we found attentional capture when the cue color matched the target color. Also, attentional capture was greater for rapid responses and with short cue–target intervals. Thus, IOR emerges when cues are relevant and do not match the target color, whereas attentional capture emerges with relevant and irrelevant cues that match the target color.     

Inhibition of return and the attentional set for integrating versus differentiating information.

Cuing a location with an uninformative cue leads to a facilitatory effect at that location shortly afterward and later (about 300 ms) to a negative effect called inhibition of return (IOR). Until recently, it was argued that IOR occurs in detection and localization tasks, but not in discrimination tasks. However, the authors of several recent studies have demonstrated IOR effects in discrimination tasks, although at a later cue-to-target stimulus onset asynchrony (SOA). In this study, the authors examined why IOR occurs at a later SOA in discrimination tasks. In Experiments 1 and 2, different time courses of exogenous cuing effects in detection and discrimination tasks were established. In Experiment 3, the authors examined the role of an attentional set on the time course of exogenous cuing effects by manipulating the proportion of trials in which a distractor is presented in the location opposite the target. A new framework for understanding exogenous cuing effects and their dependence on endogenous attention is proposed.     

Temporal ambiguity of onsets in a cueing task prevents facilitation but not inhibition of return

Cueing effects, i.e., early facilitation of reaction time and inhibition of return (IOR), are well-established and robust phenomena characterizing exogenous orienting and are widely observed in experiments with a traditional Posner cueing paradigm. Krüger, MacInnes, and Hunt (2014) proposed that facilitatory effects of peripheral cues are the result of a cue-target perceptual merging due to re-entrant visual processing. To test the role and timing of these feedback mechanisms in peripheral cueing effects, we modified the traditional cueing task in Experiments 1-3 by interleaving pre- and post-cue trials at the valid and invalid location and random cue-target onset asynchrony (CTOA) ranging from ?300 to +1,000 ms. Analysis of the manual reaction time distribution over CTOA showed well-pronounced IOR in the valid pre-cue condition and a small cost of perceptual merging in the post-cue condition, but no early facilitation of reaction time was observed in the pre-cue condition. In Experiment 4, we tested directly whether temporal ambiguity eliminated facilitation by restricting CTOAs to only the pre-cue time range and including a between-subject manipulation of a) random, b) mixed discrete, and c) blocked discrete CTOAs. Results obtained in the continuous and binned conditions showed no facilitation but robust IOR. We found both early facilitation and IOR in the blocked condition. Overall, the present findings show a small perceptual merging result without accompanying facilitation, suggesting different underlying mechanisms. Second, they demonstrate that early facilitation is likely to be affected by the presence or absence of temporal expectations and that the early onset of IOR might be masked by stronger facilitation in traditional cueing experiments.     

Successes and failures in producing attentional object-based cueing effects

Over 30?years of research using Posner's spatial cueing paradigm has shown that selective attention operates on representations of spatial locations, leading to space-based theories of attention. Manipulations of stimuli and methods have shown this paradigm to be sensitive to several types of object-based representations-providing evidence for theories incorporating object-based attentional selection. This paper critically evaluates the evidence demanding object-based explanations that go beyond positing spatial representations alone, with an emphasis on identifying and interpreting successes and failures in obtaining object-based cueing effects. This overview of current evidence is used to generate hypotheses regarding critical factors in the emergence and influence of object representations-their generation, strength, and maintenance-in the modulation of object-based facilitatory and inhibitory cueing effects.     

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.     

A time-course analysis of attentional cueing by threatening scenes

Models of attention and emotion have assigned a special status to the processing of threatening information: Facilitated attentional capture by threat and its prioritized processing would allow for swift and adequate action to potentially dangerous stimuli. In four experiments, we examined the time-course of facilitated orienting of attention to threatening scenes in the exogenous cueing paradigm. Threat value and presentation duration of the cues were systematically varied. Facilitated attentional capture by threat was limited to highly threatening pictures presented for 100 ms. No attentional effects were observed with a 28 ms cue presentation duration. At slightly longer cue presentations, 200 ms and 500 ms, results indicated no and even reduced attentional capture by threat compared with neutral information. The present results provide support for the idea that threat facilitates fast attentional orienting to its location, followed by the inhibition of attention to threat.     

The modulation of inhibition of return by objectinternal structure: Implications for theories of object-based attentional selection

Recently, Vecera, Behrmann, and McGoldrick (2000), using a divided-attention task, reported that targets are detected more accurately when they occur on the same structural part of an object, suggesting that attention can be directed toward object-internal features. We present converging evidence using the object-based inhibition of return (IOR) paradigm as an implicit measure of selection. The results show that IOR is attenuated when cues and targets appear on the same part of an object relative to when they are separated by a part boundary. These findings suggest that object-based mechanisms of selection can operate over shape representations that make explicit information about objectinternal structure.     

Inhibition of return and attentional control settings

In the present study, we used a spatial cuing paradigm in conjunction with a choice identification task to investigate whether exogenous attentional orienting and inhibition of return are affected by attentional control settings. As in previous studies (e.g., Folk, Remington, & Johnston, 1992), onset- and color-defined targets were crossed with uninformative onset- and color-defined cues. As expected, when the cue-target stimulus onset asynchrony (SOA) was short (i.e., 100 msec), the results showed that exogenous attentional orienting was contingent on attentional set; attentional capture occurred in response to a particular cue only when the feature that defined the cue also defined the target (Folk et al., 1992). More importantly, when the cue-target SOA was long (i.e., 1,000 msec), the results showed that the occurrence of inhibition of return was also contingent on attentional set, at least partially so; inhibition of return occurred in response to onset cues only when they preceded onset targets. In contrast, inhibition of return never occurred in response to color cues (at a variety of long SOAs). The associations and dissociations that were observed between exogenous attentional orienting and inhibition of return are discussed in terms of posterior and anterior attention networks in the brain (Posner & Petersen, 1990).     

Inhibition of return and object-based attentional selection

Visual attention research has revealed that attentional allocation can occur in space- and/or object-based coordinates. Using the direct and elegant design of R. Egly, J. Driver, and R. Rafal (1994), the present experiments tested whether space- and object-based inhibition of return (IOR) emerge under similar time courses. The experiments were capable of isolating both space- and object-based effects induced by peripheral and back-to-center cues. The results generally support the contention that spatially nonpredictive cues are effective in producing space-based IOR at a variety of stimulus onset asynchronies (SOAs) and under a variety of stimulus conditions. Whether facilitatory or inhibitory in direction, the object-based effects occurred over a very different time course than did the space-based effects. Reliable object-based IOR was only found under limited conditions and was tied to the time since the most recent cue (peripheral or central). The finding that object-based effects are generally determined by SOA from the most recent cue may help to resolve discrepancies in the IOR literature. These findings also have implications for the search facilitator role that IOR is purported to play in the guidance of visual attention.     

The different roles of category- and feature-specific attentional control settings on attentional enhancement and inhibition

Contingent attentional capture suggests that top-down attentional control settings (ACS) can enhance attentional processing of task-relevant properties and inhibit attentional processing of task-irrelevant properties. However, it remains unclear how ACS operates when a distractor has both task-relevant and task-irrelevant characteristics. In the present study, two lateralized ERP components, N2pc and distractor positivity (Pd), were employed as markers of attentional enhancement and inhibition, respectively. The degree of matching between a distractor and a conjunctively defined target was manipulated to illustrate attentional guidance by category-specific ACS (cACS) and feature-specific ACS (fACS), and the relative position between the distractor and the target was manipulated to isolate the processing of the distractor and the target. Experiment 1 showed that, with a long display duration for searching, a reliable N2pc component was elicited by a distractor that was feature-matched but category-mismatched (C-F+) relative to the target-defined properties, suggesting an enhancing effect of fACS. In contrast, Experiment 2 demonstrated that, with a short display duration, a Pd component was elicited by a distractor that was feature-mismatched but category-matched (C+F-) relative to the target-defined properties, suggesting an inhibitory effect of fACS. Moreover, both attentional enhancement and inhibition were only triggered by fACS but not by cACS. In summary, ACS can enhance target-relevant properties or inhibit target-irrelevant properties in response to the display duration, and fACS affects both enhancement and inhibition more than cACS.     

The effects of expectancy on inhibition of return

This research examined the influence of cue temporal predictability on inhibition of return (IOR). In exogenous attention experiments, the cue that summons attention is non-informative as to where the target will appear. However, it is predictive as to when it will appear. Because in most experiments there are equal numbers of trials for each cue-target interval (SOA--stimulus onset asynchrony), as time passes from the appearance of the cue, the probability of target presentation increases. Predictability was manipulated by using three SOA distributions: non-aging, aging and accelerated-aging. A robust IOR was found that was not modulated by temporal information within a trial. These results show that reflexive effects are relatively protected against modulation by higher volitional processes.     

Reduced habituation to angry faces: increased attentional capture as to override inhibition of return

The aim of this paper was to study whether real angry faces do capture attention to the extent of overcoming the inhibition of return (IOR) effect and whether the anxiety level of participants modulates this effect by stressing biases toward threatening stimuli. With this purpose, participants categorized the emotional valence of face targets in a standard spatial cueing procedure suitable to measure IOR. In Experiment 1, participants were selected according to their high vs. low-trait anxiety, whereas in Experiment 2 participants were induced a positive vs. anxiety mood state. The typical IOR effect was observed with neutral and happy face targets, which disappeared with angry face targets. Similar results were observed for all anxiety groups and in both experiments. The results indicate that IOR is overridden when the target is a biologically relevant angry face, as highly relevant targets should suffer less from habituation to attentional capture regardless of anxiety. We suggest that these data show that attentional capture is less likely to habituate for threatening information, so that no cost is measured in detecting new threatening information appearing at recently cued locations.     

The interplay of stop signal inhibition and inhibition of return

Inhibition of return (IOR) refers to slower responding to a stimulus that appears in the same rather than a different location as that of a preceding stimulus. The goal of the present study was to examine the relationship between IOR and stop signal inhibition. Participants were presented with two stimuli (S1 and S2) on each trial. On half of the trials (go trials), participants were required to make a speeded button-press response to report the location of S1; on the other half of trials (stop trials), they were required to cancel the response to S1, as indicated by the appearance of a stop signal at a variable delay (stop signal delay, SSD) after the appearance of S1. Success in cancelling an S1 response varied directly as a function of the SSD: The longer the delay, the more difficult it was for participants to cancel the prepared response. We examined the magnitude of IOR in the S2 reaction times as a function of whether participants made a correct go response to S1, made an erroneous non-cancelled response to S1, or successfully cancelled a response to S1. Our results indicated that the presentation of a stop signal increased the magnitude of IOR, even when the S1 response was not successfully cancelled. However, this was true only when the to-be-cancelled response involved the same effectors as the response used to reveal IOR. These results suggest that there may be a motor component to IOR that is sensitive to the same inhibitory processes that are used to cancel responses in a stop signal paradigm.