Object width modulates object-based attentional selection

Visual input typically includes a myriad of objects, some of which are selected for further processing. While these objects vary in shape and size, most evidence supporting object-based guidance of attention is drawn from paradigms employing two identical objects. Importantly, object size is a readily perceived stimulus dimension, and whether it modulates the distribution of attention remains an open question. Across four experiments, the size of the objects in the display was manipulated in a modified version of the two-rectangle paradigm. In Experiment 1, two identical parallel rectangles of two sizes (thin or thick) were presented. Experiments 2–4 employed identical trapezoids (each having a thin and thick end), inverted in orientation. In the experiments, one end of an object was cued and participants performed either a T/L discrimination or a simple target-detection task. Combined results show that, in addition to the standard object-based attentional advantage, there was a further attentional benefit for processing information contained in the thick versus thin end of objects. Additionally, eye-tracking measures demonstrated increased saccade precision towards thick object ends, suggesting that Fitts’s Law may play a role in object-based attentional shifts. Taken together, these results suggest that object-based attentional selection is modulated by object width.     

Motion direction discrimination training reduces perceived motion repulsion

Participants often exaggerate the perceived angular separation between two simultaneously presented motion stimuli, which is referred to as motion repulsion. The overestimation helps participants differentiate between the two superimposed motion directions, yet it causes the impairment of direction perception. Since direction perception can be refined through perceptual training, we here attempted to investigate whether the training of a direction discrimination task changes the amount of motion repulsion. Our results showed a direction-specific learning effect, which was accompanied by a reduced amount of motion repulsion both for the trained and the untrained directions. The reduction of the motion repulsion disappeared when the participants were trained on a luminance discrimination task (control experiment 1) or a speed discrimination task (control experiment 2), ruling out any possible interpretation in terms of adaptation or training-induced attentional bias. Furthermore, training with a direction discrimination task along a direction 150° away from both directions in the transparent stimulus (control experiment 3) also had little effect on the amount of motion repulsion, ruling out the contribution of task learning. The changed motion repulsion observed in the main experiment was consistent with the prediction of the recurrent model of perceptual learning. Therefore, our findings demonstrate that training in direction discrimination can benefit the precise direction perception of the transparent stimulus and provide new evidence for the recurrent model of perceptual learning.     

Serial dependence in position occurs at the time of perception

Observers perceive objects in the world as stable over space and time, even though the visual experience of those objects is often discontinuous and distorted due to masking, occlusion, camouflage, or noise. How are we able to easily and quickly achieve stable perception in spite of this constantly changing visual input? It was previously shown that observers experience serial dependence in the perception of features and objects, an effect that extends up to 15 seconds back in time. Here, we asked whether the visual system utilizes an object’s prior physical location to inform future position assignments in order to maximize location stability of an object over time. To test this, we presented subjects with small targets at random angular locations relative to central fixation in the peripheral visual field. Subjects reported the perceived location of the target on each trial by adjusting a cursor’s position to match its location. Subjects made consistent errors when reporting the perceived position of the target on the current trial, mislocalizing it toward the position of the target in the preceding two trials (Experiment 1). This pull in position perception occurred even when a response was not required on the previous trial (Experiment 2). In addition, we show that serial dependence in perceived position occurs immediately after stimulus presentation, and it is a fast stabilization mechanism that does not require a delay (Experiment 3). This indicates that serial dependence occurs for position representations and facilitates the stable perception of objects in space. Taken together with previous work, our results show that serial dependence occurs at many stages of visual processing, from initial position assignment to object categorization.     

Out of sight,out of mind: Occlusion and eye closure destabilize moving bistable structure-from-motion displays

Our brain constantly tries to anticipate the future by using a variety of memory mechanisms. Interestingly, studies using the intermittent presentation of multistable displays have shown little perceptual persistence for interruptions longer than a few hundred milliseconds. Here we examined whether we can facilitate the perceptual stability of bistable displays following a period of invisibility by employing a physically plausible and ecologically valid occlusion event sequence, as opposed to the typical intermittent presentation, with sudden onsets and offsets. To this end, we presented a bistable rotating structure-from-motion display that was moving along a linear horizontal trajectory on the screen and either was temporarily occluded by another object (a cardboard strip in Exp. 1, a computer-generated image in Exp. 2) or became invisible due to eye closure (Exp. 3). We report that a bistable rotation direction reliably persisted following occlusion or interruption only (1) if the pre- and postinterruption locations overlapped spatially (an occluder with apertures in Exp. 2 or brief, spontaneous blinks in Exp. 3) or (2) if an object’s size allowed for the efficient grouping of dots on both sides of the occluding object (large objects in Exp. 1). In contrast, we observed no persistence whenever the pre- and postinterruption locations were nonoverlapping (large solid occluding objects in Exps. 1 and 2 and long, prompted blinks in Exp. 3). We report that the bistable rotation direction of a moving object persisted only for spatially overlapping neural representations, and that persistence was not facilitated by a physically plausible and ecologically valid occlusion event.     

Target objects defined by a conjunction of colour and shape can be selected independently and in parallel

It is generally assumed that during search for targets defined by a feature conjunction, attention is allocated sequentially to individual objects. We tested this hypothesis by tracking the time course of attentional processing biases with the N2pc component in tasks where observers searched for two targets defined by a colour/shape conjunction. In Experiment 1, two displays presented in rapid succession (100 ms or 10 ms SOA) each contained a target and a colour-matching or shape-matching distractor on opposite sides. Target objects in both displays elicited N2pc components of similar size that overlapped in time when the SOA was 10 ms, suggesting that attention was allocated in parallel to both targets. Analogous results were found in Experiment 2, where targets and partially matching distractors were both accompanied by an object without target-matching features. Colour-matching and shape-matching distractors also elicited N2pc components, and the target N2pc was initially identical to the sum of the two distractor N2pcs, suggesting that the initial phase of attentional object selection was guided independently by feature templates for target colour and shape. Beyond 230 ms after display onset, the target N2pc became superadditive, indicating that attentional selection processes now started to be sensitive to the presence of feature conjunctions. Results show that independent attentional selection processes can be activated in parallel by two target objects in situations where these objects are defined by a feature conjunction.     

Multiple attentional control settings at distinct locations without the confounding of repetition priming

An attentional control setting (ACS), which is based on the task goal, induces involuntary attentional capture by a stimulus possessing a target-defining feature. It is unclear whether ACSs are maintained for multiple targets defined as conjunctions of a color and location. In the present study we examined the possibility of local ACSs for dual targets defined as combinations of color and location, using different paradigms: visual search in Experiment 1, and spatial cueing in Experiment 2. In Experiment 1, a distractor captured attention only when its features matched the ACSs. Likewise, in Experiment 2, a significant attentional capture effect was found only with a matching cue, whose color and location were in line with the conjunction of the target definition. Importantly, the identical pattern of attentional capture was also obtained for a neutral-color target, which was unlikely to be primed by any color of the cue. Thus, these findings imply that the attentional bias depending on the match between the cue and target did not result from cue–target repetition priming. The present study highlights that top-down attentional control can be set flexibly to accomplish a complex task goal efficiently.     

Representational momentum and anisotropies in nearby visual space

The possibility of anisotropies in visual space in and near the final location of a moving target was examined. Experiments 1 and 2 presented a moving target, and after the target vanished, participants indicated the final location of the leading or trailing edge of the target. Memory for both edges was displaced forward from the actual final locations, and the magnitude of displacement was smaller for the leading edge. Experiments 3 and 4 also presented stationary objects in front of and behind the final location of the target, and participants indicated the location of the nearest or farthest edge of one of the stationary objects. Memory for the near or far edge of an object in front of the target was displaced backward, and memory for the near or far edge of an object behind the target was displaced forward; the magnitude of displacement was larger for objects in front of the target and when the edge was farther away. The findings (a) suggest representational momentum is associated with an anisotropy of visual space that extends across and outward from the moving target and (b) are consistent with previous findings regarding estimation of time-to-contact, anorthoscopic perception, and memory psychophysics.     

Backward-walking biological motion orients attention to moving away instead of moving toward

Walking direction is an important attribute of biological motion because it carries key information, such as the specific intention of the walker. Although it is known that spatial attention is guided by walking direction, it remains unclear whether this attentional shift is reflexive (i.e., constantly shifts to the walking direction) or not. A richer interpretation of this effect is that attention is guided to seek the information that is necessary to understand the motion. To investigate this issue, we examined how backward-walking biological motion orients attention because the intention of walking backward is usually to avoid something that walking forward would encounter. The results showed that attention was oriented to the walking-away direction of biological motion instead of the walking-toward direction (Experiment 1), and this effect was not due to the gaze direction of biological motion (Experiment 2). Our findings suggest that the attentional shift triggered by walking direction is not reflexive, thus providing support for the rich interpretation of these attentional effects.     

Immunity to attentional capture at ignored locations

Certain stimuli have the power to rapidly and involuntarily capture spatial attention against our will. The present study investigated whether such stimuli capture spatial attention even when they appear in ignored regions of visual space. In other words, which force is more powerful: attentional capture or spatial filtering? Participants performed a spatial cuing task, searching for a letter target defined by color (e.g., green) and then reporting that letter’s identity. Two of the four search locations were always irrelevant. Unlike many previous experiments, participants were forced to ignore these locations because they always contained a target-colored distractor letter. Experiment 1 assessed capture by a salient-but-irrelevant abrupt onset cue appearing 150 ms before the search display. One might expect onset cues to capture attention even at ignored locations given that the main function of capture, presumably, is to rapidly alert observers to unexpected yet potentially important stimuli. However, they did not. Experiment 2 replicated this result with a different neutral baseline condition. Experiment 3 replicated the absence of capture effects at ignored locations with an even more potent stimulus: a relevant cue possessing the target color. We propose that people are effectively immune to attentional capture by objects in ignored locations – spatial filtering dominates attentional capture.     

Presaccadic target competition attenuates distraction

Although it is well known that salient nontargets can capture attention despite being task irrelevant, several studies have reported short fixation dwell times, suggesting the presence of an attentional mechanism to “rapidly reject” dissimilar distractors. Rapid rejection has been hypothesized to depend on the strong mismatch between distractor features and the target template, but it is unknown whether the presence of strong feature mismatch is sufficient, or if the presence of a target at a competing location is also necessary. Here, we investigated this question by first replicating the finding of rapid rejection for dissimilar distractors in the presence of a concurrent target (Experiment 1); manipulating the onset of the target stimulus relative to the distractor (Experiment 2); and using a saccade-contingent display to delay the target onset until after the first saccade was initiated. The results demonstrate that the speed of distractor rejection depends on the presence of target competition prior to the initiation of the first saccade, and not after the saccade. This suggests that stimulus competition for covert attention sets a “saccade priority map” that unfolds over time, resulting in faster corrective saccades to an anticipated object with higher top-down attentional priority.     

Close interpersonal proximity modulates visuomotor processing of object affordances in shared,social space

Research suggests that the human brain codes manipulable objects as possibilities for action, or affordances, particularly objects close to the body. Near-body space is not only a zone for body-environment interaction but also is socially relevant, as we are driven to preserve our near-body, personal space from others. The current, novel study investigated how close proximity of a stranger modulates visuomotor processing of object affordances in shared, social space. Participants performed a behavioural object recognition task both alone and with a human confederate. All object images were in participants’ reachable space but appeared relatively closer to the participant or the confederate. Results revealed when participants were alone, objects in both locations produced an affordance congruency effect but when the confederate was present, only objects nearer the participant elicited the effect. Findings suggest space is divided between strangers to preserve independent near-body space boundaries, and in turn this process influences motor coding for stimuli within that social space. To demonstrate that this visuomotor modulation represents a social phenomenon, rather than a general, attentional effect, two subsequent experiments employed nonhuman joint conditions. Neither a small, Japanese, waving cat statue (Experiment 2) nor a metronome (Experiment 3) modulated the affordance effect as in Experiment 1. These findings suggest a truly social explanation of the key interaction from Experiment 1. This study represents an important step toward understanding object affordance processing in real-world, social contexts and has implications broadly across fields of social action and cognition, and body space representation.     

Alertness and cognitive control: Is there a spatial attention constraint?

Congruency effects in arrow flanker tasks are often larger when subjects are more alert, suggesting an unusual connection between alertness and cognitive control. Theoretical accounts of the alerting–congruency interaction differ with respect to whether and how spatial attention is involved. In the present study, the author conducted eight experiments to determine whether there is a spatial attention constraint linking alertness to cognitive control. Alertness was manipulated in color-word Stroop tasks involving stimuli that were spatially integrated (Experiments 1–3) or separated (Experiments 4 and 5), as well as in Stroop-like tasks involving spatially separated stimuli for which the irrelevant stimulus features were spatial words (Experiments 6 and 7) or arrows (Experiment 8). All experiments yielded effects of alerting and congruency, but none produced the alerting–congruency interaction typically found with arrow flanker tasks. The results suggest that there is a spatial attention constraint on the relationship between alertness and cognitive control, part of which might involve having a task goal associated with spatial information processing.     

Visuo-haptic integration in object identification using novel objects

Although some studies have shown that haptic and visual identification seem to rely on similar processes, few studies have directly compared the two. We investigated haptic and visual object identification by asking participants to learn to recognize (Experiments 1, and 3), or to match (Experiment 2) novel objects that varied only in shape. Participants explored objects haptically, visually, or bimodally, and were then asked to identify objects haptically and/or visually. We demonstrated that patterns of identification errors were similar across identification modality, independently of learning and testing condition, suggesting that the haptic and visual representations in memory were similar. We also demonstrated that identification performance depended on both learning and testing conditions: visual identification surpassed haptic identification only when participants explored the objects visually or bimodally. When participants explored the objects haptically, haptic and visual identification were equivalent. Interestingly, when participants were simultaneously presented with two objects (one was presented haptically, and one was presented visually), object similarity only influenced performance when participants were asked to indicate whether the two objects were the same, or when participants had learned about the objects visually—without any haptic input. The results suggest that haptic and visual object representations rely on similar processes, that they may be shared, and that visual processing may not always lead to the best performance.     

Multiple high-reward items can be prioritized in working memory but with greater vulnerability to interference

Emerging literature indicates that working memory and attention interact in determining what is retained over time, though the nature of this relationship and the impacts on performance across different task contexts remain to be mapped. In the present study, four experiments examined whether participants can prioritize one or more high-reward items within a four-item target array for the purposes of an immediate cued recall task, and the extent to which this mediates the disruptive impact of a postdisplay to-be-ignored suffix. All four experiments indicated that endogenous direction of attention toward high-reward items results in their improved recall. Furthermore, increasing the number of high-reward items from one to three (Experiments 1–3) produces no decline in recall performance for those items, while associating each item in an array with a different reward value results in correspondingly graded levels of recall performance (Experiment 4). These results suggest the ability to exert precise voluntary control in the prioritization of multiple targets. However, in line with recent outcomes drawn from serial visual memory, this endogenously driven focus on high-reward items results in greater susceptibility to exogenous suffix interference, relative to low-reward items. This contrasts with outcomes from cueing paradigms, indicating that different methods of attentional direction may not always result in equivalent outcomes on working memory performance.     

The semantic category-based grouping in the Multiple Identity Tracking task

In the Multiple Identity Tracking (MIT) task, categorical distinctions between targets and distractors have been found to facilitate tracking (Wei, Zhang, Lyu, & Li in Frontiers in Psychology, 7, 589, 2016). The purpose of this study was to further investigate the reasons for the facilitation effect, through six experiments. The results of Experiments 1–3 excluded the potential explanations of visual distinctiveness, attentional distribution strategy, and a working memory mechanism, respectively. When objects’ visual information was preserved and categorical information was removed, the facilitation effect disappeared, suggesting that the visual distinctiveness between targets and distractors was not the main reason for the facilitation effect. Moreover, the facilitation effect was not the result of strategically shifting the attentional distribution, because the targets received more attention than the distractors in all conditions. Additionally, the facilitation effect did not come about because the identities of targets were encoded and stored in visual working memory to assist in the recovery from tracking errors; when working memory was disturbed by the object identities changing during tracking, the facilitation effect still existed. Experiments 4 and 5 showed that observers grouped targets together and segregated them from distractors on the basis of their categorical information. By doing this, observers could largely avoid distractor interference with tracking and improve tracking performance. Finally, Experiment 6 indicated that category-based grouping is not an automatic, but a goal-directed and effortful, strategy. In summary, the present findings show that a semantic category-based target-grouping mechanism exists in the MIT task, which is likely to be the major reason for the tracking facilitation effect.     

Numerosity estimates for attended and unattended items in visual search

The goal of this research was to examine memories created for the number of items during a visual search task. Participants performed a visual search task for a target defined by a single feature (Experiment 1A), by a conjunction of features (Experiment 1B), or by a specific spatial configuration of features (Experiment 1C). On some trials following the search task, subjects were asked to recall the total number of items in the previous display. In all search types, participants underestimated the total number of items, but the severity of the underestimation varied depending on the efficiency of the search. In three follow-up studies (Experiments 2A, 2B, and 2C) using the same visual stimuli, the participants’ only task was to estimate the number of items on each screen. Participants still underestimated the numerosity of the items, although the degree of underestimation was smaller than in the search tasks and did not depend on the type of visual stimuli. In Experiment 3, participants were asked to recall the number of items in a display only once. Subjects still displayed a tendency to underestimate, indicating that the underestimation effects seen in Experiments 1A-1C were not attributable to knowledge of the estimation task. The degree of underestimation depends on the efficiency of the search task, with more severe underestimation in efficient search tasks. This suggests that the lower attentional demands of very efficient searches leads to less encoding of numerosity of the distractor set.     

Revisiting von Restorff’s early isolation effect

An item that is conceptually or physically different from other items in a series is often remembered well. This isolation effect has been found independent of the position of the isolated item in the list, suggesting that special attention to or processing of the isolated item is not a necessary precondition of the effect. Three experiments are reported that challenge this conclusion. In Experiment 1a, we compared memory for conceptually isolated items to memory for the same items in unrelated and homogeneous lists. Under moderately distracting conditions, isolation effects were observed with midlist but not with early isolates. In fact, early isolation impaired memory for the conceptually distinct items relative to the same items in homogeneous lists. Experiment 1b replicated this memory impairment for early conceptual isolates and extended it to nondistracting conditions. In Experiment 2, we focused on early isolation, manipulating the type of isolation and whether or not participants performed judgments of learning (JOLs). An early isolation effect was observed for numbers isolated in lists of words (and vice versa), but not for conceptual isolates. Performing the JOL task reduced the size of the early isolation effect. These results suggest that number/word stimulus contrasts are coded automatically and support an isolation effect independent of list position. However, conceptual contrasts require relational processing and will only support an early isolation effect when such processing occurs. The results of Experiments 1a, 1b, and 2 suggest that attentional resources during list presentation and a favorable retrieval environment combine to support good memory for distinctive events.     

Auditory attention switching and judgment switching: Exploring multicomponent task representations

An auditory attention-switching paradigm was combined with a judgment-switching paradigm to examine the interaction of a varying auditory attention component and a varying judgment component. Participants heard two dichotically presented stimuli—one spoken by a female speaker and one spoken by a male speaker. In each trial, the stimuli were a spoken letter and a spoken number. A visual explicit cue at the beginning of each trial indicated the auditory attention criterion (speaker sex/ear) to identify the target stimulus (Experiment 1) or the judgment that had to be executed (Experiment 2). Hence, the attentional selection criterion switched independently between speaker sexes (or between ears), while the judgment alternated between letter categorization and number categorization. The data indicate that auditory attention criterion and judgment were not processed independently, regardless of whether the attention criterion or the judgment was cued. The partial repetition benefits of the explicitly cued component suggested a hierarchical organization of the auditory attention component and the judgment component within the task set. We suggest that the hierarchy arises due to the explicit cuing of one component rather than due to a “natural” hierarchy of auditory attention component and judgment component.     

Implied motion language can influence visual spatial memory

How do language and vision interact? Specifically, what impact can language have on visual processing, especially related to spatial memory? What are typically considered errors in visual processing, such as remembering the location of an object to be farther along its motion trajectory than it actually is, can be explained as perceptual achievements that are driven by our ability to anticipate future events. In two experiments, we tested whether the prior presentation of motion language influences visual spatial memory in ways that afford greater perceptual prediction. Experiment 1 showed that motion language influenced judgments for the spatial memory of an object beyond the known effects of implied motion present in the image itself. Experiment 2 replicated this finding. Our findings support a theory of perception as prediction.     

The influence of attention on value integration

People often have to make decisions based on many pieces of information. Previous work has found that people are able to integrate values presented in a rapid serial visual presentation (RSVP) stream to make informed judgements on the overall stream value (Tsetsos et al. Proceedings of the National Academy of Sciences of the United States of America, 109(24), 9659–9664, 2012). It is also well known that attentional mechanisms influence how people process information. However, it is unknown how attentional factors impact value judgements of integrated material. The current study is the first of its kind to investigate whether value judgements are influenced by attentional processes when assimilating information. Experiments 1–3 examined whether the attentional salience of an item within an RSVP stream affected judgements of overall stream value. The results showed that the presence of an irrelevant high or low value salient item biased people to judge the stream as having a higher or lower overall mean value, respectively. Experiments 4–7 directly tested Tsetsos et al.’s (Proceedings of the National Academy of Sciences of the United States of America, 109(24), 9659–9664, 2012) theory examining whether extreme values in an RSVP stream become over-weighted, thereby capturing attention more than other values in the stream. The results showed that the presence of both a high (Experiments 4, 6 and 7) and a low (Experiment 5) value outlier captures attention leading to less accurate report of subsequent items in the stream. Taken together, the results showed that valuations can be influenced by attentional processes, and can lead to less accurate subjective judgements.