Object-Based Visual Selection: Evidence From Perceptual Completion

Deployment of Attention on Handshakes

Understanding the social structures between objects, organizing, and selecting them accordingly, is fundamental to social cognition. We report an example that demonstrates the object association learned from social interactions could impact visual attention. Particularly, when two hands approach each other to perform a handshake, they tend to be attended to as a unit because of the cooperative relationship exhibited in the action: even a cue presented on a non-target hand may facilitate a response to the targets that appear on the non-cued hand (Experiment 1), indicating that attentional shift between two hands was facilitated; furthermore, the response to a target on one hand is significantly impaired by a distractor on the other hand (Experiment 2), implying that it is difficult to selectively confine attention to a single hand. These effects were dependent on the existence of the hands when cue and target appeared (Experiment 3); neither perceptual familiarity, or physical fit can explain all the attention effects (Experiment 4). These results have bearings on the perceptual root of social cognition.

How Does the Cerebral Cortex Work? Development, Learning, Attention, and 3-D Vision by Laminar Circuits of Visual Cortex

A key goal of behavioral and cognitive neuroscience is to link brain mechanisms to behavioral functions. The present article describes recent progress toward explaining how the visual cortex sees. Visual cortex, like many parts of perceptual and cognitive neocortex, is organized into six main layers of cells, as well as characteristic sublamina. Here it is proposed how these layered circuits help to realize processes of development, learning, perceptual grouping, attention, and 3-D vision through a combination of bottom-up, horizontal, and top-down interactions. A main theme is that the mechanisms which enable development and learning to occur in a stable way imply properties of adult behavior. These results thus begin to unify three fields: infant cortical development, adult cortical neurophysiology and anatomy, and adult visual perception. The identified cortical mechanisms promise to generalize to explain how other perceptual and cognitive processes work.

Temporal and Spatial Predictability of an Irrelevant Event Differently Affect Detection and Memory of Items in a Visual Sequence

We examined how the temporal and spatial predictability of a task-irrelevant visual event affects the detection and memory of a visual item embedded in a continuously changing sequence. Participants observed 11 sequentially presented letters, during which a task-irrelevant visual event was either present or absent. Predictabilities of spatial location and temporal position of the event were controlled in 2 × 2 conditions. In the spatially predictable conditions, the event occurred at the same location within the stimulus sequence or at another location, while, in the spatially unpredictable conditions, it occurred at random locations. In the temporally predictable conditions, the event timing was fixed relative to the order of the letters, while in the temporally unpredictable condition; it could not be predicted from the letter order. Participants performed a working memory task and a target detection reaction time (RT) task. Memory accuracy was higher for a letter simultaneously presented at the same location as the event in the temporally unpredictable conditions, irrespective of the spatial predictability of the event. On the other hand, the detection RTs were only faster for a letter simultaneously presented at the same location as the event when the event was both temporally and spatially predictable. Thus, to facilitate ongoing detection processes, an event must be predictable both in space and time, while memory processes are enhanced by temporally unpredictable (i.e., surprising) events. Evidently, temporal predictability has differential effects on detection and memory of a visual item embedded in a sequence of images.

The objects of visuospatial short-term memory: Perceptual organization and change detection

We used a colour change-detection paradigm where participants were required to remember colours of six equally spaced circles. Items were superimposed on a background so as to perceptually group them within (a) an intact ring-shaped object, (b) a physically segmented but perceptually completed ring-shaped object, or (c) a corresponding background segmented into three arc-shaped objects. A nonpredictive cue at the location of one of the circles was followed by the memory items, which in turn were followed by a test display containing a probe indicating the circle to be judged same/different. Reaction times for correct responses revealed a same-object advantage; correct responses were faster to probes on the same object as the cue than to equidistant probes on a segmented object. This same-object advantage was identical for physically and perceptually completed objects, but was only evident in reaction times, and not in accuracy measures. Not only, therefore, is it important to consider object-level perceptual organization of stimulus elements when assessing the influence of a range of factors (e.g., number and complexity of elements) in visuospatial short-term memory, but a more detailed picture of the structure of information in memory may be revealed by measuring speed as well as accuracy.

Facilitation by exogenous attention for static and dynamic gestalt groups

Attentional mechanisms allow the brain to selectively allocate its resources to stimuli of interest within the huge amount of information reaching its sensory systems. The voluntary component of attention, endogenous attention, can be allocated in a flexible manner depending on the goals and strategies of the observer. On the other hand, the reflexive component, exogenous attention, is driven by the stimulus. Here, we investigated how exogenous attention is deployed to moving stimuli that form distinct perceptual groups. We showed that exogenous attention is deployed according to a reference frame that moves along with the stimulus. Moreover, in addition to the cued stimulus, exogenous attention is deployed to all elements forming a perceptual group. These properties provide a basis for the efficient deployment of exogenous attention under ecological viewing conditions.

Emotional Arousal and Memory Binding: An Object-Based Framework

Binding various features of an event together and maintaining these connections in memory is an essential component of episodic memories. Previous theories make contradictory predictions about the effects of emotional arousal on memory binding. In this article, I review evidence for both arousal-impaired and arousal-enhanced memory binding and explain these contradictory findings using an object-based framework. According to this framework, emotionally arousing objects attract attention that enhances binding of their constituent features. In contrast, the emotional arousal associated with one object either impairs or has no effect on the associations between that object and other distinct objects or background contextual information. After initial encoding, the attention-grabbing nature of emotionally arousing objects can lead to interference in working memory, making it more difficult to maintain other bound representations. These contrasting effects of arousal on memory binding should help predict which aspects of emotional memories are likely to be accurate and which aspects are likely to be misremembered.

Strength of object representation: its key role in object-based attention for determining the competition result between Gestalt and top-down objects

It was found in previous studies that two types of objects (rectangles formed according to the Gestalt principle and Chinese words formed in a top-down fashion) can both induce an object-based effect. The aim of the present study was to investigate how the strength of an object representation affects the result of the competition between these two types of objects based on research carried out by Liu, Wang and Zhou [(2011) Acta Psychologica, 138(3), 397-404]. In Experiment 1, the rectangles were filled with two different colors to increase the strength of Gestalt object representation, and we found that the object effect changed significantly for the different stimulus types. Experiment 2 used Chinese words with various familiarities to manipulate the strength of the top-down object representation. As a result, the object-based effect induced by rectangles was observed only when the Chinese word familiarity was low. These results suggest that the strength of object representation determines the result of competition between different types of objects.

The effects of attention pre-allocation and target-background integration on object-based attention

Object-based attention has been documented as an important mechanism with which to control attention in several studies. To date, two main hypotheses have been proposed to interpret object-based attention: attention spreading and prioritization of search. There is evidence that supports these hypotheses in the literature. In the present study, we sought to compare these two hypotheses systematically by manipulating two factors: the integration of the target and background and the presence of attention pre-allocation. For this purpose, we used a flanker task in which the location of the task-relevant target was fixed, but the relationship between the target and the background varied. In addition, attention pre-allocation was presented in only half of the conditions. The results revealed that the attention spreading hypothesis was supported only when attention was not pre-allocated and target-background integration was high; however, the prioritization hypothesis was supported in all other conditions. Our findings provide insight into the comparisons of the attention spreading and prioritization hypotheses. Furthermore, our findings suggest that attention resources may be the underlying factor determining appropriate strategy in the control of attention.

Evidence for similar early but not late representation of possible and impossible objects

The perceptual processes that mediate the ability to efficiently represent object 3D structure are still not fully understood. The current study was aimed to shed light on these processes by utilizing spatially possible and impossible objects that could not be created in real 3D space. Despite being perceived as exceptionally unusual, impossible objects still possess fundamental Gestalt attributes and valid local depth cues that may support their initial successful representation. Based on this notion and on recent findings from our lab, we hypothesized that the initial representation of impossible objects would involve common mechanisms to those mediating typical object perception while the perceived differences between possible and impossible objects would emerge later along the processing hierarchy. In Experiment 1, participants preformed same/different classifications of two markers superimposed on a display containing two objects (possible or impossible). Faster reaction times were observed for displays in which the markers were superimposed on the same object (“object-based benefit”). Importantly, this benefit was similar for possible and impossible objects, suggesting that the representations of the two object categories rely on similar perceptual organization processes. Yet, responses for impossible objects were slower compared to possible objects. Experiment 2 was designed to examine the origin of this effect. Participants classified the location of two markers while exposure duration was manipulated. A similar pattern of performance was found for possible and impossible objects for the short exposure duration, with differences in accuracy between these two types of objects emerging only for longer exposure durations. Overall, these findings provide evidence that the representation of object structure relies on a multi-level process and that object impossibility selectively impairs the rendering of fine-detailed description of object structure.

Does temporal preparation facilitate visual processing in a selective manner? Evidence from attentional capture

The present study addressed the question of whether temporal preparation influences perceptual stimulus processing in a selective manner. In three visual search experiments, we examined whether temporal preparation aids spatial selection and thus reduces distraction caused by the onset of a task-irrelevant item. In each trial, participants had to detect a target amongst five non-targets and report a basic feature of the target. In some trials, an additional task-irrelevant singleton item (abrupt onset) appeared on the screen which distracted attention away from the target. To manipulate the degree of distraction, we varied the spatial distance and the stimulus-onset asynchrony between target and singleton. Temporal preparation for the target varied by means of constant foreperiods of different lengths. Though we observed overall faster responding in the case of high temporal preparation in all three experiments, temporal preparation did not reduce spatial distraction by the abrupt onset, even when the spatial position of the target was predictable. In sum, this pattern of results does not provide support for an influence of temporal preparation on spatial selection. Instead, it indicates that temporal preparation affects early visual processing in a non-selective manner.

Distinct mechanisms subserve location- and object-based visual attention

Visual attention can be allocated to either a location or an object, named location- or object-based attention, respectively. Despite the burgeoning evidence in support of the existence of two kinds of attention, little is known about their underlying mechanisms in terms of whether they are achieved by enhancing signal strength or excluding external noises. We adopted the noise-masking paradigm in conjunction with the double-rectangle method to probe the mechanisms of location-based attention and object-based attention. Two rectangles were shown, and one end of one rectangle was cued, followed by the target appearing at (a) the cued location; (b) the uncued end of the cued rectangle; and (c) the equal-distant end of the uncued rectangle. Observers were required to detect the target that was superimposed at different levels of noise contrast. We explored how attention affects performance by assessing the threshold versus external noise contrast (TvC) functions and fitted them with a divisive inhibition model. Results show that location-based attention – lower threshold at cued location than at uncued location – was observed at all noise levels, a signature of signal enhancement. However, object-based attention – lower threshold at the uncued end of the cued than at the uncued rectangle – was found only in high-noise conditions, a signature of noise exclusion. Findings here shed a new insight into the current theories of object-based attention.

Rhythmic sampling within and between objects despite sustained attention at a cued location

The brain directs its limited processing resources through various selection mechanisms, broadly referred to as attention. The present study investigated the temporal dynamics of two such selection mechanisms: space- and object-based selection. Previous evidence has demonstrated that preferential processing resulting from a spatial cue (i.e., space-based selection) spreads to uncued locations if those locations are part of the same object (i.e., resulting in object-based selection), but little is known about the relationship between these fundamental selection mechanisms. Here, we used human behavioral data to determine how space- and object-based selection simultaneously evolve under conditions that promote sustained attention at a cued location, varying the cue-to-target interval from 300 to 1100 ms. We tracked visual-target detection at a cued location (i.e., space-based selection), at an uncued location that was part of the same object (i.e., object-based selection), and at an uncued location that was part of a different object (i.e., in the absence of space- and object-based selection). The data demonstrate that even under static conditions, there is a moment-to-moment reweighting of attentional priorities based on object properties. This reweighting is revealed through rhythmic patterns of visual-target detection both within (at 8 Hz) and between (at 4 Hz) objects.

Prism adaptation does not alter object-based attention in healthy participants

Hemispatial neglect (‘neglect’) is a disabling condition that can follow damage to the right side of the brain, in which patients show difficulty in responding to or orienting towards objects and events that occur on the left side of space. Symptoms of neglect can manifest in both space- and object-based frames of reference. Although patients can show a combination of these two forms of neglect, they are considered separable and have distinct neurological bases. In recent years considerable evidence has emerged to demonstrate that spatial symptoms of neglect can be reduced by an intervention called prism adaptation. Patients point towards objects viewed through prismatic lenses that shift the visual image to the right. Approximately five minutes of repeated pointing results in a leftward recalibration of pointing and improved performance on standard clinical tests for neglect. The understanding of prism adaptation has also been advanced through studies of healthy participants, in whom adaptation to leftward prismatic shifts results in temporary neglect-like performance. Here we examined the effect of prism adaptation on the performance of healthy participants who completed a computerised test of space- and object-based attention. Participants underwent adaptation to leftward- or rightward-shifting prisms, or performed neutral pointing according to a between-groups design. Significant pointing after-effects were found for both prism groups, indicating successful adaptation. In addition, the results of the computerised test revealed larger reaction-time costs associated with shifts of attention between two objects compared to shifts of attention within the same object, replicating previous work. However there were no differences in the performance of the three groups, indicating that prism adaptation did not influence space- or object-based attention for this task. When combined with existing literature, the results are consistent with the proposal that prism adaptation may only perturb cognitive functions for which normal baseline performance is already biased.

Shaping attention with reward: effects of reward on space- and object-based selection

The contribution of rewarded actions to automatic attentional selection remains obscure. We hypothesized that some forms of automatic orienting, such as object-based selection, can be completely abandoned in favor of a reward-maximizing strategy. In the two experiments reported here, we presented identical visual stimuli to observers while manipulating what was being rewarded (targets in different locations from the cue or in random object locations) and the type of reward received (money or points). We found that reward alone, not the objects, guides attentional selection and thus entirely predicts behavior. These results suggest that guidance of selective attention, although automatic, is flexible and can be adjusted in accordance with external nonsensory reward-based factors.

Object-based attention without awareness

Attention and awareness are often considered to be related. Some forms of attention can, however, facilitate the processing of stimuli that remain unseen. It is unclear whether this dissociation extends beyond selection on the basis of primitive properties, such as spatial location, to situations in which there are more complex bases for attentional selection. The experiment described here shows that attentional selection at the level of objects can take place without giving rise to awareness of those objects. Pairs of objects were continually masked, which rendered them invisible to participants performing a cued-target-discrimination task. When the cue and target appeared within the same object, discrimination was faster than when they appeared in different objects at the same spatial separation. Participants reported no awareness of the objects and were unable to detect them in a signal-detection task. Object-based attention, therefore, is not sufficient for object awareness.

Attentional spreading in object-based attention: the roles of target-object integration and target presentation time

What is the best account to explain the object-based attentional benefit-that is, the spread of attention within an attended object or prioritization of search across possible target locations within an attended object? Using a task in which the location of the target was known with certainty, in the present study we systematically manipulated the type (letters or bites) and the presentation time (long or short) of the target and flankers in order to test the effects of target-object integration and target presentation time on object-based attention. The results showed that an object-based effect could appear when the target was a bite, no matter whether the target presentation time was long or short; but when the target was a letter, an object-based effect was only observed when the target presentation time was short enough. These findings provide additional evidence supporting the argument of attentional spreading in object-based attention. However, this spreading is moderated jointly by target-object integration and the target presentation time.

Visually Tracking and Localizing Expanding and Contracting Objects

The maintenance of attention on moving objects is required for cognition to reliably engage with the visual world. Theories of object tracking need to explain on which patterns of visual stimulation one can easily maintain attention and on which patterns one cannot. A previous study has shown that it is easier to track rigid objects than objects that expand and contract along their direction of motion, in a manner that resembles a substance pouring from one location to another (vanMarle and Scholl 2003 Psychological Science14 498–504). Here we investigate six possible explanations for this finding and find evidence supporting two of them. Our results show that, first, objects that expand and contract tend to overlap and crowd each other more, and this increases tracking difficulty. Second, expansion and contraction make it harder to localize objects, even when there is only a single target to attend to, and this may also increase tracking difficulty. Currently, there is no theory of object tracking that can account for the second finding.

Confuse Your Illusion

A striking example of the constructive nature of visual perception is how the human visual system completes contours of occluded objects. To date, it is unclear whether perceptual completion emerges during early stages of visual processing or whether higher-level mechanisms are necessary. To answer this question, we used transcranial magnetic stimulation to disrupt signaling in V1/V2 and in the lateral occipital (LO) area at different moments in time while participants performed a discrimination task involving a Kanizsa-type illusory figure. Results show that both V1/V2 and higher-level visual area LO are critically involved in perceptual completion. However, these areas seem to be involved in an inverse hierarchical fashion, in which the critical time window for V1/V2 follows that for LO. These results are in line with the growing evidence that feedback to V1/V2 contributes to perceptual completion.

Emergent filling in induced by motion integration reveals a high-level mechanism in filling in

The visual system is intelligent--it is capable of recovering a coherent surface from an incomplete one, a feat known as perceptual completion or filling in. Traditionally, it has been assumed that surface features are interpolated in a way that resembles the fragmented parts. Using displays featuring four circular apertures, we showed in the study reported here that a distinct completed feature (horizontal motion) arises from local ones (oblique motions)-we term this process emergent filling in. Adaptation to emergent filling-in motion generated a dynamic motion aftereffect that was not due to spreading of local motion from the isolated apertures. The filling-in motion aftereffect occurred in both modal and amodal completions, and it was modulated by selective attention. These findings highlight the importance of high-level interpolation processes in filling in and are consistent with the idea that during emergent filling in, the more cognitive-symbolic processes in later areas (e.g., the middle temporal visual area and the lateral occipital complex) provide important feedback signals to guide more isomorphic processes in earlier areas (V1 and V2).

Object-based attention guided by an invisible object

Evidence for object-based attention typically comes from studies using displays with visible objects, and little is known about whether object-based attention can occur with invisible objects. We investigated this issue with a modified double-rectangle cuing paradigm, which was originally developed by Egly et al. (J Exp Psychol Gen 123:161-177, 1994). In this study, low-contrast rectangles were presented very briefly, which rendered them invisible to subjects. With the invisible rectangles, we found a classical object-based attentional effect as indexed by the same-object effect. We also found the instantaneous object effect-object-based attention was dependent on the orientation of the rectangles presented with the target, providing evidence for the dynamic updating hypothesis (Ho and Yeh in Acta Psychol 132:31-39, 2009). These results suggest that object-based attention can be guided by an invisible object in an automatic way, with a minimal influence from high-level top-down control.

The contextual interference effect in visual feature binding: what does it say about the role of attention in binding?

The effects of blocked versus mixed presentation were tested on visual feature binding, assuming that blocked presentation enhances focused attention, whilst mixed presentation recruits extra attentional resources for intratrial as well as intertrial processing. The contextual interference effect suggests that although performance due to mixed presentation is either similar or worse than blocked presentation when tested immediately, it is better when tested after an interval. We explored whether this robust empirical effect, common in psychomotor performance, would be evident in visual feature binding. Stimuli were conjunctions of shape, colour, and location. Study-test intervals from 0 to 2,500 ms were used with a swap detection task. In Experiments 1A and 1B, participants ignored locations to detect shape-colour bindings. In Experiments 2A and 2B, they ignored shapes to detect colour-location binding. In Experiments 3A and 3B, they ignored colours to detect shape-location bindings. Whilst Experiments 1A, 2A, and 3A used blocked presentation, Experiments 1B, 2B, and 3B used mixed presentation of study-test intervals. The results of these experiments and a replication experiment using a within-subjects design showed that the contextual interference effect appeared when spatial attention was engaged, but not when attention was object based.

Object-based attention occurs regardless of object awareness

In this study, we investigated whether awareness of objects is necessary for object-based guidance of attention. We used the two-rectangle method (Egly, Driver, & Rafal, 1994) to probe object-based attention and adopted the continuous flash suppression technique (Tsuchiya & Koch, 2005) to control for the visibility of the two rectangles. Our results show that object-based attention, as indexed by the same-object advantage--faster response to a target within a cued object than within a noncued object--was obtained regardless of participants' awareness of the objects. This study provides the first evidence of object-based attention under unconscious conditions by showing that the selection unit of attention can be at an object level even when these objects are invisible--a level higher than the previous evidence for a subliminally cued location. We suggest that object-based attentional guidance plays a fundamental role of binding features in both the conscious and unconscious mind.

Neural dynamics of object-based multifocal visual spatial attention and priming: object cueing, useful-field-of-view, and crowding

How are spatial and object attention coordinated to achieve rapid object learning and recognition during eye movement search? How do prefrontal priming and parietal spatial mechanisms interact to determine the reaction time costs of intra-object attention shifts, inter-object attention shifts, and shifts between visible objects and covertly cued locations? What factors underlie individual differences in the timing and frequency of such attentional shifts? How do transient and sustained spatial attentional mechanisms work and interact? How can volition, mediated via the basal ganglia, influence the span of spatial attention? A neural model is developed of how spatial attention in the where cortical stream coordinates view-invariant object category learning in the what cortical stream under free viewing conditions. The model simulates psychological data about the dynamics of covert attention priming and switching requiring multifocal attention without eye movements. The model predicts how "attentional shrouds" are formed when surface representations in cortical area V4 resonate with spatial attention in posterior parietal cortex (PPC) and prefrontal cortex (PFC), while shrouds compete among themselves for dominance. Winning shrouds support invariant object category learning, and active surface-shroud resonances support conscious surface perception and recognition. Attentive competition between multiple objects and cues simulates reaction-time data from the two-object cueing paradigm. The relative strength of sustained surface-driven and fast-transient motion-driven spatial attention controls individual differences in reaction time for invalid cues. Competition between surface-driven attentional shrouds controls individual differences in detection rate of peripheral targets in useful-field-of-view tasks. The model proposes how the strength of competition can be mediated, though learning or momentary changes in volition, by the basal ganglia. A new explanation of crowding shows how the cortical magnification factor, among other variables, can cause multiple object surfaces to share a single surface-shroud resonance, thereby preventing recognition of the individual objects.

Time courses of attentional modulation in neural amplification and synchronization measured with steady-state visual-evoked potentials

Endogenous attention modulates the amplitude and phase coherence of steady-state visual-evoked potentials (SSVEPs). In efforts to decipher the neural mechanisms of attentional modulation, we compared the time course of attentional modulation of SSVEP amplitude (thought to reflect the magnitude of neural population activity) and phase coherence (thought to reflect neural response synchronization). We presented two stimuli flickering at different frequencies in the left and right visual hemifields and asked observers to shift their attention to either stimulus. Our results demonstrated that attention increased SSVEP phase coherence earlier than it increased SSVEP amplitude, with a positive correlation between the attentional modulations of SSVEP phase coherence and amplitude. Furthermore, the behavioral dynamics of attention shifts were more closely associated with changes in phase coherence than with changes in amplitude. These results are consistent with the possibility that attention increases neural response synchronization, which in turn leads to increased neural population activity.

How prevalent is object-based attention?

Previous research suggests that visual attention can be allocated to locations in space (space-based attention) and to objects (object-based attention). The cueing effects associated with space-based attention tend to be large and are found consistently across experiments. Object-based attention effects, however, are small and found less consistently across experiments. In three experiments we address the possibility that variability in object-based attention effects across studies reflects low incidence of such effects at the level of individual subjects. Experiment 1 measured space-based and object-based cueing effects for horizontal and vertical rectangles in 60 subjects comparing commonly used target detection and discrimination tasks. In Experiment 2 we ran another 120 subjects in a target discrimination task in which rectangle orientation varied between subjects. Using parametric statistical methods, we found object-based effects only for horizontal rectangles. Bootstrapping methods were used to measure effects in individual subjects. Significant space-based cueing effects were found in nearly all subjects in both experiments, across tasks and rectangle orientations. However, only a small number of subjects exhibited significant object-based cueing effects. Experiment 3 measured only object-based attention effects using another common paradigm and again, using bootstrapping, we found only a small number of subjects that exhibited significant object-based cueing effects. Our results show that object-based effects are more prevalent for horizontal rectangles, which is in accordance with the theory that attention may be allocated more easily along the horizontal meridian. The fact that so few individuals exhibit a significant object-based cueing effect presumably is why previous studies of this effect might have yielded inconsistent results. The results from the current study highlight the importance of considering individual subject data in addition to commonly used statistical methods.

Object-based attention: strategy versus automaticity

This article begins with a description of space- and object-based guidance of attentional selection. It goes on to discuss the most influential, two-rectangle, paradigm for demonstrating the existence of space- and object-based attentional effects. The article then considers two different mechanisms, attentional spreading and attentional prioritization, that can potentially explain how object representations come to guide attentional selection. Finally, it discusses several empirical findings that have emerged in support of the two different mechanisms. It concludes by putting forth a new framework for investigating object-based effects. WIREs Cogn Sci 2012, 3:163-169. doi: 10.1002/wcs.1162 For further resources related to this article, please visit the WIREs website.

Lexical- and perceptual-based object effects in the two-rectangle cueing paradigm

Previous studies demonstrate that attentional selection can be object-based, in which the object is defined in terms of Gestalt principles or lexical organizations. Here we investigate how attentional selection functions when the two types of objects are manipulated jointly. Experiment 1 replicated Li and Logan (2008) by showing that attentional shift between two Chinese characters is more efficient when they form a compound word than when they form a nonword. Experiment 2A presented characters either alone or within rectangles (Egly, Driver, & Rafal, 1994) and the characters in a rectangle formed either a word or a nonword. Experiment 2B differed from Experiment 2A in that the two characters forming a word were in different rectangles. Experiment 3A presented the two characters of a word either within a rectangle or in different rectangles. Experiment 3B used the same design as Experiment 3A but presented stimuli of different types in random orders, rather than in blocks as in Experiments 2A, 2B and 3A. In blocked presentation, detection responses to the target color on a character were faster when this character and the cue character formed a word than when they did not, and the size of this lexical-based object effect did not vary according to whether the two characters were presented alone or within or between rectangles. In random presentation, however, the lexical-based object effect was diminished when the two characters of a word were presented in different rectangles. Overall, these findings suggest that the processes that constrain attention deployment over conjoined objects can be strategically adjusted.

Visual cognition

Visual cognition, high-level vision, mid-level vision and top-down processing all refer to decision-based scene analyses that combine prior knowledge with retinal input to generate representations. The label "visual cognition" is little used at present, but research and experiments on mid- and high-level, inference-based vision have flourished, becoming in the 21st century a significant, if often understated part, of current vision research. How does visual cognition work? What are its moving parts? This paper reviews the origins and architecture of visual cognition and briefly describes some work in the areas of routines, attention, surfaces, objects, and events (motion, causality, and agency). Most vision scientists avoid being too explicit when presenting concepts about visual cognition, having learned that explicit models invite easy criticism. What we see in the literature is ample evidence for visual cognition, but few or only cautious attempts to detail how it might work. This is the great unfinished business of vision research: at some point we will be done with characterizing how the visual system measures the world and we will have to return to the question of how vision constructs models of objects, surfaces, scenes, and events.

Exogenous temporal cues enhance recognition memory in an object-based manner

Exogenous attention enhances the perception of attended items in both a space-based and an object-based manner. Exogenous attention also improves recognition memory for attended items in the space-based mode. However, it has not been examined whether object-based exogenous attention enhances recognition memory. To address this issue, we examined whether a sudden visual change in a task-irrelevant stimulus (an exogenous cue) would affect participants' recognition memory for items that were serially presented around a cued time. The results showed that recognition accuracy for an item was strongly enhanced when the visual cue occurred at the same location and time as the item (Experiments 1 and 2). The memory enhancement effect occurred when the exogenous visual cue and an item belonged to the same object (Experiments 3 and 4) and even when the cue was counterpredictive of the timing of an item to be asked about (Experiment 5). The present study suggests that an exogenous temporal cue automatically enhances the recognition accuracy for an item that is presented at close temporal proximity to the cue and that recognition memory enhancement occurs in an object-based manner.

Subliminal spatial cues capture attention and strengthen between-object link

According to the spreading hypothesis of object-based attention, a subliminal cue that can successfully capture attention to a location within an object should also cause attention to spread throughout the whole cued object and lead to the same-object advantage. Instead, we propose that a subliminal cue favors shifts of attention between objects and strengthens the between-object link, which is coded primarily within the dorsal pathway that governs the visual guidance of action. By adopting the two-rectangle method and using an effective subliminal cue to compare with the classic suprathreshold cue, we found a different result pattern with suprathreshold cues than with subliminal cues. The suprathreshold cue replicated the conventional location and object effects, whereas a subliminal cue led to a different-object advantage with a facilitatory location effect and a same-object advantage with an inhibitory location effect. These results support our consciousness-dependent shifting hypothesis but not the spreading hypothesis.

Investigating the status of biological stimuli as objects of attention in multiple object tracking

BACKGROUND

Humans are able to track multiple simultaneously moving objects. A number of factors have been identified that can influence the ease with which objects can be attended and tracked. Here, we explored the possibility that object tracking abilities may be specialized for tracking biological targets such as people.

METHODOLOGY/PRINCIPAL FINDINGS

We used the Multiple Object Tracking (MOT) paradigm to explore whether the high-level biological status of the targets affects the efficiency of attentional selection and tracking. In Experiment 1, we assessed the tracking of point-light biological motion figures. As controls, we used either the same stimuli or point-light letters, presented in upright, inverted or scrambled configurations. While scrambling significantly affected performance for both letters and point-light figures, there was an effect of inversion restricted to biological motion, inverted figures being harder to track. In Experiment 2, we found that tracking performance was equivalent for natural point-light walkers and 'moon-walkers', whose implied direction was incongruent with their actual direction of motion. In Experiment 3, we found higher tracking accuracy for inverted faces compared with upright faces. Thus, there was a double dissociation between inversion effects for biological motion and faces, with no inversion effect for our non-biological stimuli (letters, houses).

CONCLUSIONS/SIGNIFICANCE

MOT is sensitive to some, but not all naturalistic aspects of biological stimuli. There does not appear to be a highly specialized role for tracking people. However, MOT appears constrained by principles of object segmentation and grouping, where effectively grouped, coherent objects, but not necessarily biological objects, are tracked most successfully.

First come, first served? Influence of changed object configuration on object-based attention

Evidence for object-based attention is based mainly on studies using object displays that remain unchanged throughout, with the assumption that object representation should be completed and stabilized before it is selected for further processing. We used the modified double-rectangle cuing paradigm of Egly, Driver, and Rafal (Journal of Experimental Psychology: General, 123, 161-177, 1994) but introduced a configuration change to the cued-object display to test whether object-based attention is determined by the cued- or, alternatively, the changed-object display. Four small rectangles were presented in the initial display; critically, after one was cued, an occluder was presented to make the four small rectangles amodally completed into the double-rectangle configuration. Results show that object-based attention is determined by the changed display, but not by the cued display. This suggests that object-based attention is an interactively evolving process between object representation and attention, rather than a serial process in which attention operates after object representation is completed.

Object-based attention in chimpanzees (Pan troglodytes)

We conducted three experiments to investigate how object-based components contribute to the attentional processes of chimpanzees and to examine how such processes operate with regard to perceptually structured objects. In Experiment 1, chimpanzees responded to a spatial cueing task that required them to touch a target appearing at either end of two parallel rectangles. We compared the time involved in shifting attention (cost of attentional shift) when the locations of targets were cued and non cued. Results showed that the cost of the attentional shift within one rectangle was smaller than that beyond the object's boundary, demonstrating object-based attention in chimpanzees. The results of Experiment 2, conducted with different stimulus configurations, replicated the results of Experiment 1, supporting that object-based attention operates in chimpanzees. In Experiment 3, the cost of attentional shift within a cued but partly occluded rectangle was shorter than that within a rectangle that was cued but divided in the middle. The results suggest that the attention of chimpanzees is activated not only by an explicit object but also by fragmented patches represented as an object at a higher-order perceptual level. Chimpanzees' object-based attention may be similar to that of humans.