The unilateral field advantage in repetition detection: Effects of perceptual grouping and task demands

This study examines interhemispheric interactions in detecting objects that are simultaneously repeated in an array of objects. Previous studies have shown that presenting two identical objects to a single hemifield speeds up repetition detection. This unilateral field advantage (UFA) is often attributed to the relatively low-level processing demands for detecting a perceptual repetition, and more specifically, to more efficient perceptual grouping processes within a hemisphere than between hemispheres. To directly examine the impact of perceptual grouping and task demands on interhemispheric interactions, we asked participants to judge whether four items, one presented in each visual quadrant, were all different, or whether any two were the same, along an instructed dimension. We found that in comparison with the UFA for identical objects, the UFA for repetition detection in accuracy was similar or greater when the matching objects were not perceptually identical and differed in color, size, or viewpoint. Thus, decreasing grouping strength and increasing computational complexity did not reduce the UFA. Results are interpreted in terms of the callosal degradation account of the UFA.     

The case for proprioception

In formulating a theory of perception that does justice to the embodied and enactive nature of perceptual experience, proprioception can play a valuable role. Since proprioception is necessarily embodied, and since proprioceptive experience is particularly integrated with one’s bodily actions, it seems clear that proprioception, in addition to, e.g., vision or audition, can provide us with valuable insights into the role of an agent’s corporal skills and capacities in constituting or structuring perceptual experience. However, if we are going to have the opportunity to argue from analogy with proprioception to vision, audition, touch, taste, or smell, then it is necessary to eschew any doubts about the legitimacy of proprioception’s inclusion into the category of perceptual modalities. To this end, in this article, I (1) respond to two arguments that Shaun Gallagher (2003) presents in “Bodily self-awareness and objectperception” against proprioception’s ability to meet the criteria of object perception, (2) present a diagnosis of Gallagher’s position by locating a misunderstanding in the distinction between proprioceptive information and proprioceptive awareness, and (3) show that treating proprioception as a perceptual modality allows us to account for the interaction of proprioception with the other sensory modalities, to apply the lessons we learn from proprioception to the other sensory modalities, and to account for proprioceptive learning. Finally, (4) I examine Sydney Shoemaker’s (1994) identification constraint and suggest that a full-fledged notion of object-hood is unnecessary to ground a theory of perception.     

SEEING TWO AS ONE:

Abstract -Object tokens are episodic visual representations that mediate the ability to track visual events as they move about and change over time. Multiple tokens also allow the viewer to individuate multiple instances of a single type of object. In the present study, we established a functional link for object tokens in two seemingly disparate visual phenomena: apparent motion and repetition blindness [RB]. In RB, repeated items are more difficult to perceive than unre-peated items. Using displays in which two sets of alphanumeric characters streamed in opposite directions across a computer screen in apparent motion, we found increased RB for targets appearing within a single apparent motion stream, relative to targets in different apparent motion streams. The results are inconsistent with refractory period or memory retrieval accounts of RB and support the role of object tokens in both apparent motion and RB.     

Object-based warping: an illusory distortion of space within objects

Visual objects are high-level primitives that are fundamental to numerous perceptual functions, such as guidance of attention. We report that objects warp visual perception of space in such a way that spatial distances within objects appear to be larger than spatial distances in ground regions. When two dots were placed inside a rectangular object, they appeared farther apart from one another than two dots with identical spacing outside of the object. To investigate whether this effect was object based, we measured the distortion while manipulating the structure surrounding the dots. Object displays were constructed with a single object, multiple objects, a partially occluded object, and an illusory object. Nonobject displays were constructed to be comparable to object displays in low-level visual attributes. In all cases, the object displays resulted in a more powerful distortion of spatial perception than comparable non-object-based displays. These results suggest that perception of space within objects is warped.     

Effects of grouping and attention on the perception of causality

Beyond perceiving patterns of motion in simple dynamic displays, we can also perceive higher level properties, such as causality, as when we see one object collide with another object. Although causality is a seemingly high-level property, its perception--like the perception of faces or speech--often appears to be automatic, irresistible, and driven by highly constrained and stimulus-driven rules. Here, in an exploration of such rules, we demonstrate that perceptual grouping and attention can influence the both perception of causality in ambiguous displays. We first report several types of grouping effects, based on connectedness, proximity, and common motion. We further suggest that such grouping effects are mediated by the allocation of attention, and we directly demonstrate that causal perception can be strengthened or attenuated on the basis of where observers are attending, independent of fixation. Like Michotte, we find that the perception of causality is mediated by strict visual rules. Beyond Michotte, we find that these rules operate not only over discrete objects, but also over perceptual groups, constrained by the allocation of attention.     

Keeping an eye on the violinist: motor experts show superior timing consistency in a visual perception task

Common coding theory states that perception and action may reciprocally induce each other. Consequently, motor expertise should map onto perceptual consistency in specific tasks such as predicting the exact timing of a musical entry. To test this hypothesis, ten string musicians (motor experts), ten non-string musicians (visual experts), and ten non-musicians were asked to watch progressively occluded video recordings of a first violinist indicating entries to fellow members of a string quartet. Participants synchronised with the perceived timing of the musical entries. Results revealed significant effects of motor expertise on perception. Compared to visual experts and non-musicians, string players not only responded more accurately, but also with less timing variability. These findings provide evidence that motor experts’ consistency in movement execution—a key characteristic of expert motor performance—is mirrored in lower variability in perceptual judgements, indicating close links between action competence and perception.     

汉字部件水平的重复知盲效应

本研究采用不同部件特点的汉字材料考察在汉字部件水平的重复知盲效应。实验1探究在一组刺激序列中,当两个关键刺激R1和R2的相同部件在不同位置时对重复知盲效应的影响。实验1结果表明,不同条件的重复知盲效应存在显著差异,但其中两个关键字中相同部件的位置相同时与部件位置不同时之间的重复知盲效应无显著差异,这表明部件位置对重复知盲现象无显著影响。实验2探究当关键刺激R1和R2为部件包含关系时的重复知盲效应。实验2结果表明,当一个关键刺激为独体字,且是另一个关键刺激的部件时存在重复知盲效应,其效应的大小会受到具有包含关系的两个关键字（合体字和独体字）在刺激序列中出现顺序的影响,当第二个关键刺激为独体字时的重复知盲效应要显著强于第二个关键刺激为合体字条件。研究结论是不同的汉字部件特点会影响重复之盲效应,这表明重复知盲现象很可能发生在在线的知觉加工过程。     

RSVP任务下双刺激重复的优势与劣势

本研究探讨重复知盲发生在知觉阶段还是在记忆阶段。采用快速视觉系列呈现(rapid serial visual representation, 简称RSVP)任务, 让被试即时回忆80个词表中呈现的词。操作了词表中目标词的重复数, 分为无重复、单刺激重复(重复一对)和双刺激重复(重复两对)三种, 和目标词的情绪效价, 分为中性词和情绪词两种。结果发现, 对目标词回忆的正确率是：当目标词和非目标词都是中性词汇, 即二者的情绪效价强度相当时(实验1), 在无重复条件与双刺激重复条件下无差异, 二者均大于单刺激重复条件; 当目标词是消极词汇, 非目标词是中性词汇, 即目标刺激的情绪效价强度大于非目标刺激时(实验2), 无重复条件与单刺激重复条件无差异, 二者均大于双刺激重复条件。结果表明：(1)RSVP 任务下词表中有双刺激重复时, 如果刺激的效价强度相当, 出现重复优势; 如果目标刺激的效价强度高于非目标刺激, 出现重复劣势; (2)人们会主动分配更多的注意资源给效价高的刺激, 重复知盲产生在记忆阶段, 支持注意资源分配最优化假设。     

How do humans group non-rigid objects in multiple object tracking?: Evidence from grouping by self-rotation

Previous studies on perceptual grouping found that people can use spatiotemporal and featural information to group spatially separated rigid objects into a unit while tracking moving objects. However, few studies have tested the role of objects’ self-motion information in perceptual grouping, although it is of great significance to the motion perception in the three-dimensional space. In natural environments, objects always move in translation and rotation at the same time. The self-rotation of the objects seriously destroys objects’ rigidity and topology, creates conflicting movement signals and results in crowding effects. Thus, this study sought to examine the specific role played by self-rotation information on grouping spatially separated non-rigid objects through a modified multiple object tracking (MOT) paradigm with self-rotating objects. Experiment 1 found that people could use self-rotation information to group spatially separated non-rigid objects, even though this information was deleterious for attentive tracking and irrelevant to the task requirements, and people seemed to use it strategically rather than automatically. Experiment 2 provided stronger evidence that this grouping advantage did come from the self-rotation per se rather than surface-level cues arising from self-rotation (e.g. similar 2D motion signals and common shapes). Experiment 3 changed the stimuli to more natural 3D cubes to strengthen the impression of self-rotation and again found that self-rotation improved grouping. Finally, Experiment 4 demonstrated that grouping by self-rotation and grouping by changing shape were statistically comparable but additive, suggesting that they were two different sources of the object information. Thus, grouping by self-rotation mainly benefited from the perceptual differences in motion flow fields rather than in deformation. Overall, this study is the first attempt to identify self-motion as a new feature that people can use to group objects in dynamic scenes and shed light on debates about what entities/units we group and what kinds of information about a target we process while tracking objects.     

What is a visual object? Evidence from target merging in multiple object tracking

The notion that visual attention can operate over visual objects in addition to spatial locations has recently received much empirical support, but there has been relatively little empirical consideration of what can count as an 'object' in the first place. We have investigated this question in the context of the multiple object tracking paradigm, in which subjects must track a number of independently and unpredictably moving identical items in a field of identical distractors. What types of feature clusters can be tracked in this manner? In other words, what counts as an 'object' in this task? We investigated this question with a technique we call target merging: we alter tracking displays so that distinct target and distractor locations appear perceptually to be parts of the same object by merging pairs of items (one target with one distractor) in various ways - for example, by connecting item locations with a simple line segment, by drawing the convex hull of the two items, and so forth. The data show that target merging makes the tracking task far more difficult to varying degrees depending on exactly how the items are merged. The effect is perceptually salient, involving in some conditions a total destruction of subjects' capacity to track multiple items. These studies provide strong evidence for the object-based nature of tracking, confirming that in some contexts attention must be allocated to objects rather than arbitrary collections of features. In addition, the results begin to reveal the types of spatially organized scene components that can be independently attended as a function of properties such as connectedness, part structure, and other types of perceptual grouping.     

When story characters communicate: readers’ representations of characters’ linguistic exchanges

Klin, Ralano, and Weingartner (2007) found transfer effects when a phrase, described as part of a note one character had left for another, was repeated across two passages. However, when the phrase was part of a note in story A and part of a conversation in story B, transfer effects were eliminated (Klin & Drumm, 2010). Klin and Drumm concluded that readers encoded the perceptual features of story characters’ linguistic exchanges and that the mismatch (visual vs. auditory) eliminated transfer effects. The present experiments support this conclusion and also demonstrate that readers encode details of the social interaction that surrounds the characters’ linguistic exchanges: Effects were reduced when the phrase in story A was part of a direct social interaction between the characters (e.g., phone conversation), whereas in story B, the interaction was indirect (e.g., voicemail). More generally, readers are exquisitely tuned to subtle aspects of characters’ linguistic exchanges.     

Orientation-invariant object recognition: evidence from repetition blindness

The question of whether object recognition is orientation-invariant or orientation-dependent was investigated using a repetition blindness (RB) paradigm. In RB, the second occurrence of a repeated stimulus is less likely to be reported, compared to the occurrence of a different stimulus, if it occurs within a short time of the first presentation. This failure is usually interpreted as a difficulty in assigning two separate episodic tokens to the same visual type. Thus, RB can provide useful information about which representations are treated as the same by the visual system. Two experiments tested whether RB occurs for repeated objects that were either in identical orientations, or differed by 30, 60, 90, or 180 degrees . Significant RB was found for all orientation differences, consistent with the existence of orientation-invariant object representations. However, under some circumstances, RB was reduced or even eliminated when the repeated object was rotated by 180 degrees , suggesting easier individuation of the repeated objects in this case. A third experiment confirmed that the upside-down orientation is processed more easily than other rotated orientations. The results indicate that, although object identity can be determined independently of orientation, orientation plays an important role in establishing distinct episodic representations of a repeated object, thus enabling one to report them as separate events.     

Visual events modulated by sound in repetition blindness

Repetition blindness (RB; Kanwisher, 1987) is the term used to describe people’s failure to detect or report an item that is repeated in a rapid serial visual presentation (RSVP) stream. Although RB is, by definition, a visual deficit, whether it is affected by an auditory signal remains unknown. In the present study, we added two sounds before, simultaneous with, or after the onset of the two critical visual items during RSVP to examine the effect of sound on RB. The results show that the addition of the sounds effectively reduced RB when they appeared at, or around, the critical items. These results indicate that it is easier to perceive an event containing multisensory information than unisensory ones. Possible mechanisms of how visual and auditory information interact are discussed.     

Interaction of semantic and perceptual processes in repetition blindness

Two experiments examined the effect of activation of higher-level semantic representations on lower-level perceptual representations. A forced-choice discrimination paradigm was used, a method known to produce repetition blindness (RB) for words unconfounded by memory demands or response bias. In Experiment 1, equivalent reductions in RB (as measured by omission error rate and by d') occurred when successive word pairs were identical in: (1) form, pronunciation, and meaning (both uppercase versions of the same word); (2) pronunciation and meaning but not form (lowercase versus uppercase; lexical identity); and (3) pronunciation, but not form or meaning (homonyms; phonological identity), relative to when the words were unrelated on all dimensions. The RB effect was markedly attenuated, but not eliminated, when the words were semantically related. Similar results were obtained in Experiment 2 using a larger group of subjects. These findings show that higher-order semantic representations can have a top-down influence on judgements based on lower-order perceptual representations. The results are discussed within the framework of a cascade model of object processing in the human brain.     

Semantic picture-word interference is a postperceptual effect

Naming a picture is slower while ignoring a semantically related versus an unrelated distractor word (semantic picture–word interference, or PWI). To locate the PWI effect in the word production processing stream (during perceptual encoding, response selection, or afterward), we used the psychological refractory period paradigm, in which participants identified a tone and then, at varying SOAs, named a picture while ignoring a semantically related or unrelated word (following Dell’Acqua, Job, Peressotti, & Pascali, 2007). As in results from the Stroop paradigm (Fagot & Pashler, 1992), we found equivalent PWI effects at short and long SOAs following tone identification in two experiments, indicating that semantic competition occurs at response selection or later. Our results suggest that it is premature to assume that competitive selection occurs at multiple levels in the word production system (van Maanen, van Rijn, & Borst, 2009) or that the Stroop and semantic PWI effects are fundamentally different (Dell’Acqua et al., 2007).     

Repetition blindness under minimum memory load: Effects of spatial and temporal proximity and the encoding effectiveness of the first item

Repetition blindness (RB) refers to the reduced performance in reporting a repeated as opposed to a nonrepeated item in rapid serial visual presentation. In Experiment 1, we found RB for two-item stimuli in uncertain locations. The magnitude of RB decreased significantly with increases in interstimulus interval, but not with increases in spatial separation, indicating that RB is determined primarily by temporal factors. In Experiment 2, we found RB when subjects were required to report only the second of two successively presented items. The magnitude of RB increased with the duration of the first item, indicating that RB is determined by the encoding effectiveness of the first item. The results of this study collectively indicate that RB is not a memory or a sensory phenomenon, but rather a perceptual phenomenon occurring at the stage of identity encoding. The findings also undermine the arguments (Kanwisher, 1987) that have been offered in favor of the type-token binding failure hypothesis and indicate instead that type-node refractoriness may be the cause of RB.     

Spatial modulation of repetition blindness and repetition deafness

When two identical visual items are presented in rapid succession, people often fail to report the second instance when trying to recall both (e.g., Kanwisher, 1987). We investigated whether this temporal processing deficit is modulated by the spatial separation between the repeated stimuli within both audition and vision. In Experiment 1, lists of one to three digits were rapidly presented from loudspeaker cones arranged in a semicircle around the participant. Recall accuracy was lower when repeated digits were presented from different positions rather than from the same position, as compared to unrepeated control pairs, demonstrating that auditory repetition deafness (RD) is modulated by the spatial displacement between repeated items. A similar spatial modulation of visual repetition blindness (RB) was reported when pairs of masked letters were presented visually from either the same or different positions arranged on a semicircle around fixation (Experiment 2). These results cannot easily be accounted for by the token individuation hypothesis of RB (Kanwisher, 1987; Park & Kanwisher, 1994) and instead support a recognition failure account (Hochhaus & Johnston, 1996; Luo & Caramazza, 1995, 1996).     

知觉组织对时序知觉的双重影响:同时判断任务的证据

本研究探讨知觉组织对时序知觉的双重影响。实验采用三条线段构成的C形为实验材料,操纵图形朝向和SOA水平(实验1和实验2)、图形颜色(实验3)以及反应限制(实验4),要求被试完成同时判断任务。结果发现,在不同的SOA条件下,图形对向条件的同时判断频率均显著高于图形反向条件(实验1),即使在知觉组织线索弱化时这种现象仍然存在(实验2和实验3),而且知觉组织对时序知觉的影响不是由于被试的反应偏向导致的(实验4)。结果说明知觉组织对时序知觉存在双重影响:当两个刺激同时出现时,知觉组织能够提高时序知觉表现; 而当两个刺激非同时出现时,知觉组织显著降低时序知觉表现。     

The differentiation of rhythmic structure

Listeners judged whether two five-tone nonmetric rhythms were the same or different. Each rhythm was presented one, two, or four times to study the process of perceptual differentiation. The results indicated that the listeners perceived these rhythms in-terms.of the grouping of the tones, and not in terms of the timing between the groups. Two rhythms that had the same perceptual grouping were judged as being identical, even if the timing between the groups was different. The perception of the groupings of tones developed gradually. If each rhythm was presented only once, then the listeners had only a global percept, focused on groups (runs) of three elements, and often judged two different rhythms as being identical. If the rhythms were presented two or four times, then the grouping of the tones became more differentiated and the listeners were less likely to judge different patterns as being identical. Thus, perception of auditory rhythmic structure appears to follow the same developmental process as the perception of visual spatial structure.     

The temporality of Merleau-Ponty’s intertwining

In his last work, The Visible and the Invisible, Merleau-Ponty explored the fact that we believe that perception occurs in our heads (“in the recesses of a body”) and, hence, assert that the perceptual world is “in” us, while also believing that we are “in” the world we perceive.  In this article, I examine how this intertwining of self and world justifies the faith we have in perception. I shall do so by considering a number of examples.  In each case, the object “in itself” will turn out to be neither within us nor outside of us, but rather at the intersection set by the intertwining. I will then turn to what this disclosure of this object reveals about human temporality and, indeed, about human being as a place (or “clearing”) that permits disclosure.