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

Imagined object files: Visual imagery produces partial repetition costs where perception does not

The present study explored whether object (or event) files can be formed that integrate color imagery and perceptual location features. To assess this issue, a cue-target procedure was used whereby color imagery was cued to be generated at a particular location in space, which was then followed by a perceptual color discrimination task. Partial repetition costs (PRCs) were then measured by varying the overlap of the color and location features of the cue and target to evaluate whether an object/event file was formed. Robust PRCs were observed when imagery was generated at a location, supporting the idea that imagery and perception can be incorporated into a common event file. It was also revealed that the PRC effects for perceptual color cues were tenuous-they did not reach significance in the present study. Overall, the present study indicates that imagery can produce stronger binding effects than perception, offering important insights into the role that active engagement plays in the formation of object/event files.

Detection cost: A nonnegligible factor contributing to inhibition of return in the discrimination task under the cue-target paradigm

The three-factor model argues that the spatial orienting benefit triggered by the cue, the spatial selection benefit of cue-target matching, and the detection cost of distinguishing the cue from the target contribute to the measured inhibition of return (IOR) effect. According to the three-factor model, the spatial selection benefit dominates the occurrence of the IOR effect in the discrimination task, while the detection cost is negligible. The present study verified the three-factor model in the discrimination task under the cue-target paradigm by manipulating the spatial location and nonspatial feature consistency of the cue and the target as well as the promotion or hindrance of attentional disengagement from the cued location with a central reorienting cue. The results indicated that the three factors of the three-factor model contributed to the measured IOR effect in the discrimination task. Interestingly, the IOR effect was stable when the cue and target were perfectly repeated and attention was maintained at the cued location, implying that detection cost was not a negligible factor. The current study supported the contribution of all three factors in the three-factor model to the measured IOR effect; however, we argue that the role of detection cost in the discrimination task under different paradigms should be further refined.

Location-response binding and inhibition of return in a detection task

In the present study, we investigated the binding of location and response in a detection task of the target-target paradigm of inhibition of return (IOR). Results showed a cost of responding to a target at the repeated location (IOR) when the response was not repeated and an effect of facilitation of return (FOR) when the response was repeated. These findings suggest that when responding to a target, its location and the response to it are integrated together. In addition, an analysis of the Vincentized cumulative response time (RT) distribution further showed that memory retrieval of event representations requires time to operate. These findings were discussed according to the theoretical framework of event files.

When do response-related episodic retrieval effects co-occur with inhibition of return?

At some point, spatial priming effects more faithfully reflect response selection processes than they do attentional orienting or sensory processes. Findings from the spatial cueing literature suggest that two factors may be critical: (1) the amount of identity processing that is required in order to respond correctly (feature-based response hypothesis), and (2) the amount of spatial processing that is required in order to respond correctly (space-based response hypothesis). To test the first hypothesis, we manipulated whether observers made single keypress detection or two-choice localization responses to serially presented stimuli in peripheral vision and whether stimulus identity information processing was necessary before responding. Responses were always slowest when the target location repeated, consistent with an attentional orienting bias independent of keypress responding (i.e., inhibition of return; IOR). The localization procedure revealed a subtle additional cost for changing the target location and repeating a response, consistent with a response-related episodic retrieval effect predicted by the Theory of Event Coding (TEC). Neither effect was modulated by the need to discriminate features. To test the second hypothesis, we made spatial processing indispensable to response selection by requiring a decision between a detection and localization response, depending on where the target appeared. IOR was eliminated for detection, but not localization, responses, consistent with the TEC. Collectively, the findings suggest that the amount of space-based, but not feature-based, processing that is required to determine a response is responsible for the response retrieval effects that can co-occur with IOR.

Visual working memory load does not eliminate visuomotor repetition effects

When we respond to a stimulus, our ability to quickly execute this response depends on how combinations of stimulus and response features match to previous combinations of stimulus and response features. Some kind of memory representations must be underlying these visuomotor repetition effects. In this paper, we tested the hypothesis that visual working memory stores the stimulus information that gives rise to these effects. Participants discriminated the colors of successive stimuli while holding either three locations or colors in visual working memory. If visual working memory maintains the information about a previous event that leads to visuomotor repetition effects, then occupying working memory with colors or locations should selectively disrupt color-response and location-response repetition effects. The results of two experiments showed that neither color nor spatial memory load eliminated visuomotor repetition effects. Since working memory load did not disrupt repetition effects, it is unlikely that visual working memory resources are used to store the information that underlies visuomotor repetitions effects. Instead, these results are consistent with the view that visuomotor repetition effects stem from automatic long-term memory retrieval, but can also be accommodated by supposing separate buffers for visual working memory and response selection.

Dissociating Orienting Biases From Integration Effects With Eye Movements

Despite decades of research, the conditions under which shifts of attention to prior target locations are facilitated or inhibited remain unknown. This ambiguity is a product of the popular feature discrimination task, in which attentional bias is commonly inferred from the efficiency by which a stimulus feature is discriminated after its location has been repeated or changed. Problematically, these tasks lead to integration effects; effects of target-location repetition appear to depend entirely on whether the target feature or response also repeats, allowing for several possible inferences about orienting bias. To parcel out integration effects and orienting biases, we designed the present experiments to require localized eye movements and manual discrimination responses to serially presented targets with randomly repeating locations. Eye movements revealed consistent biases away from prior target locations. Manual discrimination responses revealed integration effects. These data collectively revealed inhibited reorienting and integration effects, which resolve the ambiguity and reconcile episodic integration and attentional orienting accounts.

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.

The Influence of Social and Nonsocial Variables on the Simon Effect

Abstract. Recently, the Simon effect (SE) has been observed in social contexts when two individuals share a two-choice task. This joint SE (JSE) has been interpreted as evidence that people co-represent their actions. However, it is still not clear if the JSE is driven by social factors or low-level mechanisms. To address this question, we applied a common paradigm to a joint Simon task (Experiments 1 and 4), a standard Simon task (Experiment 2), and a go/no-go task (Experiment 3). The results showed that both the JSE and the SE were modulated by the repetition/non-repetition of task features. Moreover, the JSE was differently modulated by the gender composition of the two individuals involved in the shared task and by their interpersonal relationship. Taken together, our results do not support a pure social explanation of the JSE, nevertheless, they show the independent role of different social factors in modulating the effect.

Attentional cueing by cross-modal congruency produces both facilitation and inhibition on short-term visual recognition

The attentional modulation of performance in a memory task, comparable to the one obtained in a perceptual task, is at the focus of contemporary research. We hypothesized that a biphasic effect (namely, facilitation followed by inhibition) can be obtained in visual working memory when attention is cued towards one item of the memorandum and participants must recognize a delayed probe as being identical to any item of the memorandum. In every trial, a delayed spiky/curvy probe appeared centrally, to be matched with the same-category shape maintained in visual working memory which could be either physically identical (positive trials) or only categorically similar (negative trials). To orient the participant's attention towards a selected portion of a two-item memorandum, a (tzk/wow) sound was played simultaneously with two lateral visual shapes (one spiky and one curved). Our results indicate that an exogenous attentional shift during perception of the memorandum, induced by a congruent audio-visual pairing, first facilitates and then inhibits the recognition of a cued item (but not of a non-cued item) stored in visual working memory. A coherent pattern of individual differences emerged, indicating that the amount of early facilitation in congruent-sound trials was negatively correlated with recognition sensitivity in no-sound trials (suggesting that the inverse effectiveness rule may also apply to memory) and positively correlated with later inhibition, as well as with the self-reported susceptibility to memory failures.

Larger IOR effects following forget than following remember instructions depend on exogenous attentional withdrawal and target localization

When words are onset in the visual periphery, inhibition of return (IOR) for a subsequent target is larger when those words receive an intervening forget instruction than when they receive a remember instruction Taylor (Quarterly Journal of Experimental Psychology, 58A, 613-629, 2005). The present study manipulated the allocation of endogenous and exogenous attention to assess the source of the forget > remember IOR difference. We determined that the forget > remember IOR difference likely arises from the differential withdrawal of exogenous-rather than endogenous-attention. Furthermore, this forget > remember IOR difference occurs only when a spatially compatible localization response is required; it does not occur when a simple detection response or a perceptual discrimination is required. This suggests that the forget > remember difference in the magnitude of IOR is not due to differences in perceptual/attentional processing. Instead, an instruction to remember or forget biases spatial responses in accordance with whether a location has previously contained relevant or irrelevant information. We suggest that directed forgetting in an item-method paradigm is not accomplished by changes in attention; rather, the changes in attention are coincident with changes in memory and may serve to bias later responses away from a source of unreliable information.

Facilitation versus inhibition in non-spatial attribute discrimination tasks

Inhibition of Return is a delay in initiating attentional shifts to previously inspected locations. It has been explained as a mechanism to facilitate visual search of a scene by inhibiting the allocation of attention to locations that have already been examined. We (Hu, Samuel, & Chan, Journal of Experimental Psychology: General, 2010) recently demonstrated that similar processing costs can appear when a non-spatial attribute (color or shape) repeats-detection of a target stimulus was slower if the target shared color or shape with a recently presented cue. In the current study, we test whether such inhibitory effects occur for non-spatial attribute repetition when observers must make a discrimination judgment about targets. We found two independent effects: First, there was a standard location-based IOR effect-target discrimination was slower when the target appeared in the same location as a preceding cue. Second, reaction times were faster if the target's color or shape matched the cue's color or shape; this facilitation effect contrasts with both the location-based inhibition that was present in the current experiments, and with the inhibitory effect of feature repetition in our previous detection task study. The data are best accounted for by a three-factor model recently suggested by Lupiáñez (Attention and time, 2010).

Eliminating inhibition of return by changing salient nonspatial attributes in a complex environment

Inhibition of return (IOR) occurs when a target is preceded by an irrelevant stimulus (cue) at the same location: Target detection is slowed, relative to uncued locations. In the present study, we used relatively complex displays to examine the effect of repetition of nonspatial attributes. For both color and shape, attribute repetition produced a robust inhibitory effect that followed a time course similar to that for location-based IOR. However, the effect only occurred when the target shared both the feature (i.e., color or shape) and location with the cue; this constraint implicates a primary role for location. The data are consistent with the idea that the system integrates consecutive stimuli into a single object file when attributes repeat, hindering detection of the second stimulus. The results are also consistent with an interpretation of IOR as a form of habituation, with greater habituation occurring with increasing featural overlap of a repeated stimulus. Critically, both of these interpretations bring the IOR effect within more general approaches to attention and perception, rather than requiring a specialized process with a limited function. In this view, there is no process specifically designed to inhibit return, suggesting that IOR may be the wrong framing of inhibitory repetition effects. Instead, we suggest that repetition of stimulus properties can interfere with the ability to focus attention on the aspects of a complex display that are needed to detect the occurrence of the target stimulus; this is a failure of activation, not an inhibition of processing.

The effect of age on inhibition of return is independent of non-ocular response inhibition

Inhibition of return (IOR) refers to the slowing of a response to a target stimulus presented in the same location as a previous stimulus. Increased IOR has been observed in older adults, despite a reduction in other 'inhibitory' processes. However, cue-target tasks have been used in all previous studies and because of this, IOR may have been overestimated due to non-ocular response inhibition associated with withholding a response from the cue. Could increased levels of response inhibition account for the observations of increased IOR in older adults? This confound can be circumvented by using a target-target paradigm, in which a response is made to all stimuli. We tested three groups of 24 subjects: young (mean 22.5 years), young-old (mean 61.9 years) and old-old (mean 74.8 years). Subjects completed both visual cue-target and target-target tasks with identical inter-stimulus intervals of 1400 and 1800ms. IOR magnitude increased with age in both the cue-target task and the target-target task. Furthermore, the magnitude of visual IOR was found to increase with age even when individual differences in baseline response speed were taken into account. Thus, there appears to be a genuine increase in IOR magnitude with age.

Inhibition of return in cue–target and target–target tasks

Inhibition of return (IOR), the term given for the slowing of a response to a target that appeared at the same location as a previously presented stimulus, has been studied with both target-target (TT; participants respond to each successive event) and cue-target (CT; participants only respond to the second of two events) tasks. Although both tasks have been used to examine the processes and characteristics of IOR, few studies have been conducted to understand if there are any differences in the processes that underlie the IOR that results from ignoring (CT paradigm) or responding to (TT paradigm) the first stimulus. The purpose of the present study was to examine the notion that IOR found in TT tasks represents "true" IOR whereas IOR found in CT tasks consist of both "true" IOR and response inhibition (Coward et al. in Exp Brain Res 155:124-128, 2004). Consistent with the pattern of effects found by Coward et al. (Exp Brain Res 155:124-128, 2004), IOR was larger in the CT task than in the TT task when a single detection response was required (Experiment 1). However, when participants completed one of two spatially-directed responses (rapid aiming movement to the location of the target stimulus), IOR effects from the CT and TT tasks were equal in magnitude (Experiment 2). Rather than CT tasks having an additional response inhibition component, these results suggest that TT tasks may show less of an inhibitory effect because of a facilitatory response repetition effect.

Different effects of exogenous cues in a visual detection and discrimination task: delayed attention withdrawal and/or speeded motor inhibition?

Several studies examining spatial attention have found a discrepancy regarding the effects of exogenous cues on reaction times in visual detection and discrimination tasks. Namely, across a wide range of cue-target intervals, responses are slower for targets at cued than at uncued locations (inhibition of return) in detection tasks, whereas responses are faster for targets at cued than at uncued locations (facilitation) in discrimination tasks. Two hypotheses were proposed to account for this discrepancy. First, attention may dwell much longer on the exogenously cued location in discrimination tasks because stimuli have to be identified (i.e., the delayed attention withdrawal hypothesis). Secondly, due to increased motor preparation in detection tasks, cue-induced motor inhibition may rise much faster in these tasks than in discrimination tasks (i.e., the speeded motor inhibition hypothesis). We examined to what extent these hypotheses can account for effects of exogenous cues in a detection and discrimination task on the extrastriate P1 component, and the onset of motor activation, as indexed by the lateralized readiness potential. Some support was found for the delayed attention withdrawal hypothesis, as task-dependent cueing effects were found on the P1 component. Other aspects of our data, however, indicate that motor inhibition is also involved. Based on these findings, we propose that effects of exogenous cues in detection and discrimination tasks are determined by the interplay between two mechanisms, of which the time courses of activation may be modulated by the specific setting.

Inhibition of return: Sensitivity and criterion as a function of response time

Inhibition of return (IOR) refers to a mechanism that results in a performance disadvantage typically observed when targets are presented at a location once occupied by a cue. Although the time course of the phenomenon--from the cue to the target--has been well studied, the time course of the effect--from target to response--is unknown. In 2 experiments, the effect of IOR upon sensitivity and response criterion under different levels of speed stress was examined. In go/no-go and choice reaction time tasks, IOR had at least 2 distinct effects on information processing. Early in target processing, before sufficient target information has accrued, there is a bias against responding to cued targets. Later, as target information is allowed to accrue, IOR reduces sensitivity to the target's nonspatial feature. Three accounts relating to the early bias effect of IOR and the late effect of IOR on sensitivity are offered.

Inhibition of return and response repetition within and between modalities

Inhibition of return (IOR) refers to slower responding to stimuli at previously occupied spatial locations. IOR has been vigorously studied because of its possible deep involvement with attention mechanisms. Although IOR occurs both within and across modalities in several experimental paradigms for simple stimulus detection tasks, it has sometimes been difficult to demonstrate in perceptual discrimination tasks. In the preferred target-target paradigm, in which responses are made to a series of targets that vary in spatial location, failure to find IOR could possibly result from mixing of spatial IOR with the facilitating effects of stimulus and/or response repetition on discrimination response times. In this paper we report the first demonstration of auditory/auditory and cross-modality IOR in a target-target paradigm using a discrimination task. Our results show that IOR occurs in this task only on trials on which stimuli and responses are not repeated. These findings present a challenge to purely visual accounts of IOR and support the view that IOR arises within a more general, supra-modal mechanism of attention.

Event files: feature binding in and across perception and action

The primate brain codes perceived events in a distributed fashion, which raises the question of how the codes referring to the same event are related to each other. Recent findings suggest that they are integrated into 'object files', episodic bindings of object-related information. However, the problem of integrating distributed codes is not restricted to perception but applies to action planning and sensorimotor processing as well. Here I argue that the brain addresses these problems by creating multi-layered networks of bindings - 'event files' - that temporarily link codes of perceptual events, the current task context, and the actions performed therein. These bindings produce systematic but often surprising and counter-intuitive interactions between, and impairments in, perception and action planning.

The contribution of non-ocular response inhibition to visual inhibition of return

Inhibition of return (IOR) refers to slowed responses to targets presented at the same location as a preceding stimulus. IOR is typically investigated using a cue-target design, in which subjects respond only to the second stimulus of a pair. In such tasks, the measurement of 'true' IOR may be confounded by the effect of non-ocular response inhibition, because the participant must suppress any tendency to respond (e.g. key press) to the first stimulus. This confound may be eliminated using a target-target design, in which responses are made to both stimuli. We assessed the contribution of non-ocular response inhibition to visual IOR, measured in a cue-target task, by testing participants on both cue-target and target-target detection tasks, with identical timings and stimuli. Significant IOR was obtained in both tasks but, at a stimulus onset asynchrony (SOA) of 1400 ms, IOR magnitude was significantly greater in the cue-target condition than in the target-target condition. However, at an SOA of 1800 ms, there was no significant difference in the magnitude of IOR between the two tasks. Thus, a proportion of the total IOR effect observed in visual cue-target tasks can be attributed to non-ocular response inhibition, but this process appears to decay more rapidly than does 'true' IOR, having dissipated by 1800 ms following cue onset.