Objects and their locations in exogenous cuing

Anatomical, physiological, and behavioral studies provide support for separate object- and locationbased components of visual attention. Although studies of object-based components have usually involved voluntary attention, more recent evidence has suggested that objects may play an independent role in reflexiveexogenous orienting, at least at long stimulus onset asynchronies (SOAs). In the present experiments, the role of objects in reflexive attentional orienting was investigated by developing a task in which location and object cuing could be separately examined for both short and long SOAs. Typical location cuing effects were obtained, indicating facilitation at short cue—target intervals and inhibition of return (IOR) at longer intervals. In contrast, object cuing resulted in facilitation for cued objects at long cue—target intervals and no object-based IOR. Interestingly, object cuing primarily affected targets at cued locations, and not those at uncued locations. Together, the experiments examine the interactive nature of objects and locations in exogenous orienting and seem most consistent with a location-mediated view of object-based orienting.     

Object-based visual attention with endogenous orienting

In a series of experiments, we examined covert orienting using endogenous cuing, in which attention is voluntarily directed toward a peripheral location. In one experiment, subjects were cued to attend to one end of an oblong object. They then detected targets on the cued object or elsewhere. In another experiment, subjects provided judgments of the relative temporal order of two flashes after their attention had moved endogenously. In a third experiment, subjects were directed to attend to an empty spatial location and subsequently discriminated features of objects that appeared at or near the locus of attention. In each of these situations, attentional orienting was object based, in the sense that nonattended locations that were on the cued object had an advantage over nonattended locations that were not on the object. The results are discussed in terms of their implications for object-based representations and the differences between exogenous and endogenous orienting of attention.     

Inhibition of return for objects and locations in static displays

When orienting attention, inhibition mechanisms prevent the return of attention to previously examined stimuli. This inhibition of the return of attention (IOR) has been shown to be associated additively with location- and object-based representations. That is, when static objects are attended, IOR is associated with both the object and the location cued, and hence IOR is larger than when only spatial location is attended. Recently McAuliffe, Pratt, and O'Donnell (2001) failed to observe such additive effects except under a narrow set of conditions (at short cue-target intervals and using mixed blocks in which object- and pure location-based effects were probed in the same display). The present study shows that additive IOR effects are observed under conditions that violate all of these boundary conditions. The results also show that IOR is modulated by internal structural properties of objects. These findings are cosistent with the hypothesis that IOR operates over functionally independent object- and location-based frames of reference.     

On the uniqueness of attentional capture by uninformative gaze cues: facilitation interacts with the Simon effect and is rarely followed by IOR.

Orienting to an uninformative peripheral cue is characterized by a brief facilitation followed by a long-lasting inhibition once attention is removed from the cued location. Although central gaze cues cause reflexive orienting, the inhibitory effect that is relatively ubiquitous following exogenous orienting to uninformative peripheral cues has been relatively rare. We hypothesized that IOR might be seen following gaze-induced orienting if attention were effectively returned to centre by a return gaze or return flash. The timecourse of gaze-directed orienting was measured by varying the interval between the gaze cue and a peripheral target requiring an orientation discrimination (permitting measurement of the Simon effect). Significant facilitation was observed at all but the longest SOA tested, 2,880 ms, by which time the facilitation had disappeared with no evidence of IOR. Gaze-induced cuing (which was unaffected by return cue condition) interacted with the Simon effect, decreasing it at the gazed-at location, a pattern that is not seen with more typical endogenous and exogenous cuing.     

The involvement of bottom-up saliency processing in endogenous inhibition of return

Participants are faster at detecting a visual target when it appears at a cued, as compared with an uncued, location. In general, a reversal of this cost-benefit pattern is observed after exogenous cuing when the cue-target interval exceeds approximately 250?ms (inhibition of return [IOR]), and not after endogenous cuing. We suggest that, usually, no IOR is found with endogenous cues because no bottom-up saliency-based orienting processes are claimed. Therefore, we developed an endogenous feature-based split-cue task to allow for endogenous saliency-based orienting. IOR was observed in the saliency-driven endogenous cuing condition, and not in the control condition that prevented saliency-based orienting. These results suggest that usage of saliency-based orienting processes in either endogenous or exogenous orienting warrants the appearance of IOR.     

The manifestation of attentional capture: facilitation or IOR depending on task demands

Orienting attention exogenously to a location can have two different consequences on processing subsequent stimuli appearing at that location: positive (facilitation) at short intervals and negative (inhibition of return) at long ones. In the present experiments, we manipulated the frequency of targets and responses associated with them. Results showed that, even at long SOAs, where IOR is usually observed, facilitation was observed for infrequent targets at the same time that IOR was measured for frequent targets. These results are difficult to explain on the basis of either task set modulation of attentional capture or task set modulation of subsequent orienting processes. In contrast, we offer an explanation by which the different cuing effects can be considered as different manifestations of attentional capture on target processing, depending on the task set.     

Scene-based and object-centered inhibition of return: evidence for dual orienting mechanisms

We investigated whether inhibition of return (IOR) could be observed in location-based, scene-based, and object-centered frames of reference. IOR was found to move both with a separate cued object (scene-based) and with a location within a single rotating object (object-centered). Importantly, however, IOR was also associated with the environmental location cued when cuing was of a separate object (scene-based), whereas facilitation of the cued location was found when cuing was of a component within an object. These results suggest that location is of central importance to scene-based representations of separate objects, which appear to be encoded in viewer-centered coordinates, whereas environmental locus is of little relevance when attention orients within a single object. The results also provide further evidence for the coexistence of both excitation and inhibition associated with uninformative exogenous cues.     

Inhibition of return in manual and saccadic response systems

When nonpredictive exogenous visual cues are used to reflexively orient covert visual spatial attention, the initial early facilitation for detecting stimuli at cued versus uncued spatial locations develops into inhibition by 300 msec following the cue, a pattern referred to as inhibition of return (IOR). Experiments were carried out comparing the magnitude and time course for development of IOR effects when manual versus saccadic responses were required. The results showed that both manual and saccadic responses result in equivalent amounts of facilitation following initial exposure to a spatial cue. However, IOR developed more quickly for saccadic responses, such that, at certain cue-target SOAs, saccadic responses to targets were inhibited, whereas manual responses were still facilitated. The findings are interpreted in terms of a premotor theory of visual attention.     

动态情景中颜色特征和身份特征在返回抑制中的作用

在动态的“线索-靶子”范式中引入隧道刺激, 以靶子与线索的非空间特征相同时的反应延迟测量返回抑制效应。实验1利用单向隧道创设客体的空间位置信息明确且可靠的条件, 考察客体的颜色特征在返回抑制中的作用。实验2利用双向隧道创设客体的空间位置信息不明确的条件, 考察客体的颜色特征在返回抑制中的独立作用。实验3、4分别采用与实验1、2类似的方法, 在动态任务情景中考察客体的身份特征在返回抑制中的作用。结果显示, 线索呈现与靶子呈现的时间间隔较长时, 4个实验中均存在显著的返回抑制效应。这表明, 动态情景中, 客体的空间位置信息明确且可靠时, 颜色特征和身份特征在返回抑制中都发挥着重要作用; 客体的空间位置信息不明确时, 颜色特征和身份特征在返回抑制中也都具有相对独立的作用。     

Oculomotor inhibition of return: Evidence against object-centered representation

ABSTRACT

Intermixing central, directional arrow targets with the peripheral targets typically used in the Posnerian spatial cueing paradigm offers a useful diagnostic for ascertaining the relative contributions of output and input processes to oculomotor inhibition of return (IOR). Here, we use this diagnostic to determine whether object-based oculomotor IOR comprises output and/or input processes. One of two placeholder objects in peripheral vision was cued, then both objects rotated smoothly either 90 or 180 degrees around the circumference of an imaginary circle. After this movement, a saccade was made to the location marked by a peripheral onset target or indicated by the central arrow. In our first three experiments, whereas there was evidence for IOR when measured by central arrow or peripheral onset targets at cued locations, there was little trace of IOR at the cued object. We thereafter precisely replicated the seminal experiment for object-based oculomotor IOR (Abrams, R. A., & Dobkin, R. S. (1994). Inhibition of return: Effects of attentional cuing on eye movement latencies. Journal of Experimental Psychology: Human Perception and Performance, 20(3), 467–477; Experiment 4) but again found little evidence of an object-based IOR effect. Finally, we ran a paradigm with only peripheral targets and with motion and stationary trials randomly intermixed. Here we again showed IOR at the cued location but not at the cued object. Together, the findings suggest that object-based representation of oculomotor IOR is much more tenuous than implied by the literature.     

Spatiotemporal distribution of facilitation and inhibition of return arising from the reflexive orienting of covert attention

Currently, there is debate regarding both the spatial and temporal relationship between facilitation and inhibition of return (IOR) components of attention, as observed on the covert orienting of visual attention task (COVAT). These issues were addressed in a series of experiments where the spatial and temporal relationships between cue and target were manipulated. Facilitation occurred only when the stimulus onset asynchrony (SOA) was short and there was temporal overlap between cue and target. IOR occurred only when SOA was long and there was no temporal overlap between cue and target. Facilitation encompassed the cued location and all locations between the cue and fixation, whereas IOR arose for the entire cued hemifield. These findings suggest that the facilitation and IOR found on COVATs that use noninformative peripheral cues are separable and stimulus-driven processes.     

Emotional and hemispheric asymmetries in shifts of attention: An ERP study

Inhibition of return (IOR) refers to the larger response time to cued targets appearing at long cue-to-target intervals. Given emotion–attention interactions and associated visual field (VF) asymmetries, we examined the effects of emotions and hemispheric processing on object- and location-based IOR. We expected reduced IOR and right hemispheric bias accompanied by differences in event-related potentials (ERPs) including lack of suppression of cued N1 and enhancement of Nd components for sad targets. Reaction times and ERPs were recorded in an exogenous cuing detection task using happy and sad schematic faces. Results revealed reduced IOR for left compared to right VF with sad faces but no such asymmetry for happy faces. Cued N1 amplitudes were suppressed for happy targets but not for sad targets presented to the left VF. Nd amplitudes were enhanced for right-hemispheric sad faces especially with object-based IOR. The results indicate right-hemispheric advantage in the capture of attention by negative emotion especially with object-based selection.     

Emotional and hemispheric asymmetries in shifts of attention: an ERP study

Inhibition of return (IOR) refers to the larger response time to cued targets appearing at long cue-to-target intervals. Given emotion-attention interactions and associated visual field (VF) asymmetries, we examined the effects of emotions and hemispheric processing on object- and location-based IOR. We expected reduced IOR and right hemispheric bias accompanied by differences in event-related potentials (ERPs) including lack of suppression of cued N1 and enhancement of Nd components for sad targets. Reaction times and ERPs were recorded in an exogenous cuing detection task using happy and sad schematic faces. Results revealed reduced IOR for left compared to right VF with sad faces but no such asymmetry for happy faces. Cued N1 amplitudes were suppressed for happy targets but not for sad targets presented to the left VF. Nd amplitudes were enhanced for right-hemispheric sad faces especially with object-based IOR. The results indicate right-hemispheric advantage in the capture of attention by negative emotion especially with object-based selection.     

Configural and contextual prioritization in object-based attention

When attention is directed to a location within an object, other locations within that object also enjoy an attentional advantage. Recently we demonstrated that this object-based advantage is mediated by increased attentional priority assigned to locations within an already attended object and not to early sensory enhancement due to the "spread" of attention within the attended object (Shomstein & Yantis, 2002). At least two factors might contribute to the assignment of attentional priority, one related to the configuration of objects in a scene and the other related to the probability of target appearance in each location imposed by task contingencies. We investigated the relative contribution of these factors by cuing one end of one of a pair of rectangles; a subsequent target appeared most often in the cued location. We manipulated attentional priority setting by varying (1) the probability that a target would appear in each of two uncued locations and (2) the cue to target stimulus onset asynchrony (SOA). On invalidly cued trials, the target appeared in the high-probability location (defined by an absolute spatial location, e.g., upper right) 83% of the time and in the low-probability location (e.g., lower left) 17% of the time. In both conditions, uncued targets appeared in the cued object half the time and in the uncued object half the time. At short SOAs, the same-object and probability effects were approximately additive. However, at longer SOAs, the same-object effects disappeared, and reaction times depended exclusively on location probability. These results suggest that observers adopt an implicit configural scanning strategy (in which unattended locations within an attended object have high priority) or an implicit contextual scanning strategy (in which objectively high-probability locations have high priority) depending on task contingencies and the amount of time that is available to deploy attention.     

Inhibition of return in response to gaze cues: The roles of time course and fixation cue

Recent studies have demonstrated that orienting of attention in response to nonpredictive gaze cues arises rapidly and automatically, in a similar fashion to peripheral sudden onset cueing. However, while peripheral cues consistently elicit inhibition of return (IOR) at about 300 ms following cue onset, very little is known about inhibition effects in response to gaze cues. The present experiments systematically examined the conditions under which IOR arises with such cues. Reliable inhibition effects were obtained. Importantly, IOR emerged only at long cue-target intervals and only when a second cue actively triggered attention away from the cued location. This suggests that compared to sudden onset cueing, gaze cueing results in both prolonged facilitation and a delayed onset of inhibition processes. Thus, although both types of cues elicit very similar orienting effects in terms of their basic behavioural outcomes, there are more subtle differences between gaze and peripheral cues with respect to the maintenance and quality of those cueing effects across time.     

Stimulus discrimination following covert attentional orienting to an exogenous cue.

Five experiments explored exogenous covert visual-attentional orienting following a brief peripheral cue. On each trial an attentional cue was followed by a stimulus in an empty field at 1 of 8 locations on an imaginary circle centered on the fixation point. The cued area size and the cue-target spatial relation were manipulated. Accuracy and response time were affected by the exogenous cue validity. Attention was allocated to a specific location in a visual quadrant: A target at an uncued location in a quadrant was not facilitated as much as target at the cued location, and a target in a different quadrant was inhibited in relation to a neutral condition. Cuing 2 locations in a quadrant was not as facilitative for targets at the cued locations or as inhibitive for targets at other locations compared with cuing a single location in a quadrant. Results are discussed in the context of several extent models of covert visual-spatial attention.     

Inhibition of return spreads across 3-D space

Focusing attention to a location in 3–D space operates much the same as in 2–D space. Attending a location in 2–D space is followed by a selective inhibitory aftereffect known as inhibition of return (IOR). Here, we report the results of two 3–D reflexive cuing studies in which depth was defined by binocular disparity. As has been shown before, attentional cuing was specific for x–y–z locations. However, the present results show that IOR is not depth specific. After a specific location in x–y–z is cued, IOR occurs for the depth plane in front of and behind the cued location. The finding that IOR spreads across depth planes may be related to how inhibited locations are encoded in the superior colliculus. We argue that the functional role of a depth–blind IOR is to bias attention against going back to any part of a previously attended object.     

Age-related differences in object- and location-based inhibition of return of attention

Four experiments examined age-related differences in inhibition of return (IOR) of visual attention. Using static stimuli, both young and older adults were slower to detect targets in previously cued objects, showing equivalent IOR. With objects that moved after they had been cued, young adults were slower to detect targets in the cued object (compared with uncued ones), revealing object-based IOR, but older adults were faster to detect targets in such objects, failing to demonstrate object-based IOR. Both age groups were slower to detect targets at the initially cued location (location-based IOR). The results show that age has a differential effect on IOR depending on the frame of reference of the inhibition: Inhibition for objects breaks down with age, but that for location does not. This pattern of results is consistent with the view that there are specific inhibitory deficits in old age.     

返回抑制时程的三因素理论及其发展

综述了返回抑制(Inhibition of return,IOR)出现时程机制的三因素理论内容,支持该理论的实验证据,以及对理论的质疑和发展。该理论认为空间定向收益、出现检测缺失和空间选择收益三个因素共同决定了IOR出现的时程及机制。研究者通过操控任务加工水平或将实验范式相结合的方式对三因素理论提出了质疑和发展。许多关键问题如三个因素存在的认知神经科学证据、出现检测缺失和空间选择收益发挥作用的方式等是未来研究的重点和方向。     

Objects do not aid inhibition of return in crossing the vertical meridian

Location-based cuing experiments have shown that inhibition of return (IOR) spreads beyond a cued location but appears to be confined to the cued hemifield by the vertical meridian. Previous studies have also shown that IOR can spread across objects and here we investigate whether an object can be used to mediate the spreading of IOR into the opposite hemifield. Two experiments used a rectangular object that surrounded four target locations, two to the left and right of a central fixation point. The spreading of IOR in the presence of the object was determined and compared with a condition where the object-frame was absent. Object-present and object-absent trials were either mixed within a block (Experiment 1) or divided into separate blocks (Experiment 2). Both experiments revealed robust inhibition in the cued but not the uncued hemifield, further demonstrating the hemifield-based spreading of IOR.