Grouping does not require attention

Attention, Perception, & Psychophysics, 2010

Representing the visual world efficiently requires selecting a fraction of the multitude of information that is available to the visual system at any one instant in time. Much recent research has been devoted to understanding the psychological and neural processes underlying the attentional selection of incoming information (Corbetta & Shulman, 2002; Reynolds & Heeger, 2009; Shomstein & Yantis, 2006; Yantis et al., 2002), but there still remains considerable controversy concerning the fate of the sensory information that is not selected for preferential processing. That is, when an observer selectively attends to some subset of the visual input, the degree and nature of the processing to which the remaining, unattended input is subjected remains largely unspecified. Part of the problem in deriving a definitive answer to this issue arises first from the difficulty in knowing with certainty that the unselected information is, in fact, unattended, and second from developing a paradigm that targets just this unattended information. It is not particularly contentious that, after the light hits the retina, some amount of visual processing is accomplished, regardless of whether the specific information is attended or not. What remains more uncertain, however, is the extent to which the unattended information is processed perceptually (e.g., segmented into figure/ground, grouped, etc.). Previous investigations of attentional involvement in different types of perceptual processing vary from studies of how scenes are perceived (Bieder

2010

Representing the visual world efficiently requires selecting a fraction of the multitude of information that is available to the visual system at any one instant in time. Much recent research has been devoted to understanding the psychological and neural processes underlying the attentional selection of incoming information (Corbetta & Shulman, 2002; Reynolds & Heeger, 2009; Shomstein & Yantis, 2006; Yantis et al., 2002), but there still remains considerable controversy concerning the fate of the sensory information that is not selected for preferential processing. That is, when an observer selectively attends to some subset of the visual input, the degree and nature of the processing to which the remaining, unattended input is subjected remains largely unspecified. Part of the problem in deriving a definitive answer to this issue arises first from the difficulty in knowing with certainty that the unselected information is, in fact, unattended, and second from developing a paradigm that targets just this unattended information. It is not particularly contentious that, after the light hits the retina, some amount of visual processing is accomplished, regardless of whether the specific information is attended or not. What remains more uncertain, however, is the extent to which the unattended information is processed perceptually (e.g., segmented into figure/ground, grouped, etc.). Previous investigations of attentional involvement in different types of perceptual processing vary from studies of how scenes are perceived (Bieder

Perception & Psychophysics, 2007

Acta Psychologica, 1999

Perceptual organization can be viewed as the selection of the best or ``most reasonable'' parse of a given scene. However, the principles that determine which interpretation is most reasonable have resisted most attempts to de®ne them formally. This paper summarizes a formal theory of human perceptual organization, called minimal model theory, in which the best interpretation of a given scene is expressed as the formally minimal interpretation in a well-de®ned space of possible interpretations. We then focus speci®cally on the role of types of grouping units, in particular the dicult notion of ``object''. Although grouping is often thought of as the process of dividing the image into objects, most research in perceptual grouping actually focuses on simpler types of units, such as contours and surfaces. Minimal model theory characterizes grouping units at a logical level, demonstrating how formal assumptions about units induce the observer to place a certain preference ranking on interpretations. The theory is then applied to the more subtle problem of objects, culminating in a de®nition for objects that is formally rigorous but at the same time captures some of the ¯exibility of human intuitions about objects.

2002

Recent research shows that, under certain conditions, visual attention is object-based. That is, attention preferentially selects objects in the visual field. These objects are processed, culminating in object recognition. On this formulation, the objects selected by attention are perceptual groups determined by the principles of perceptual organization of Gestalt psychology. These groups are formed independently of attentional processes and conceptual knowledge. This view is not consistent with available data about the visual system, which shows that perceptual organization is sensitive to conceptual information, depends on attentional processes, and infers representations that best explain the visual stimulus. Here, I propose a new account of visual attention that aims to correct these limitations of the Gestalt-based formulation. The nature of the object representations underlying perceptual and attentional mechanisms is discussed. It is proposed that attention and perception int...

Psychological Science, 2012

Visual perception starts with localized filters that subdivide the image into fragments that undergo separate analyses. The visual system has to reconstruct objects by grouping image fragments that belong to the same object. A widely held view is that perceptual grouping occurs in parallel across the visual scene and without attention. To test this idea, we measured the speed of grouping in pictures of animals and vehicles. In a classification task, these pictures were categorized efficiently. In an image-parsing task, participants reported whether two cues fell on the same or different objects, and we measured reaction times. Despite the participants' fast object classification, perceptual grouping required more time if the distance between cues was larger, and we observed an additional delay when the cues fell on different parts of a single object. Parsing was also slower for inverted than for upright objects. These results imply that perception starts with rapid object classification and that rapid classification is followed by a serial perceptual grouping phase, which is more efficient for objects in a familiar orientation than for objects in an unfamiliar orientation.

Perception & Psychophysics, 1975

The role of element proximity in perceptual grouping was examined in tasks requmng speeded discrimination of two-element visual patterns. Grouping of two elements was defined as the failure of attention to be focused on one element selectively in filtering tasks where only that one element was relevant to the discrimination. Failure of selective attention was measured by the degree of interference caused by variation of the irrelevant element. Grouping was shown to diminish monotonically as the spacing between two elements was increased. At a given spacing, grouping could be reduced or eliminated by the introduction of a third element into the stimulus field, presumably because the addition of this element triggered a reorganization of the perceptual field into a new grouping structure. Grouping appeared to facilitate performance on condensation tasks requiring distributed attention, to the degree that the condensation tasks were actually easier than the filtering tasks at close proximities. Paradoxically, for some tasks, moving an irrelevant element away from a relevant one actually impaired performance, suggesting that paying attention to irrelevant information could be beneficial. This result, if generalizable, suggests that grouping be conceptualized not as an automatic process under preattentive control but as an optional process under strategic control. This paper is concerned with two aspects of the problem 01 perceptual organization of visual arrays . The first is the degree to which perceptual organization is under the control of specitic parameters of the stimulus array, as opposed to cognitive (strategic) factors within the observer. The second is the establishment of experimental measures of organizational processes. This latter issue is much more than simply a methodological one, for in order to measure organization a theory is required that explains just what organization means, and how and where organization enters into the processing of perceptual information. The Gestalt "laws" of course represented an attempt to answer the first question. Certain stimulus variables. some well defined (proximity) and some not so well defined (similarity), can be shown to have clear effects on the wayan observer reports his perception of stimulus arrays. The conclusions one can draw from these demonstrations. as compelling as the perceptual effects may be, are limited, however. to the domain of phenomenology and say little about the underlying processes that shape our perceptual experiences. What is required are performance measures. rather than subjective reports. of perceptual organization. argued that if organization is more than an epiphenomenon. there

Journal of Experimental Psychology: Human Perception and Performance, 2002

Earlier studies have shown that attention can be directed to objects, defined on the basis of generic grouping principles, highly familiar shapes, or task instructions, rather than to contiguous regions of the visual field. The 4 experiments presented in this article extend these findings, showing that object attention benefits-shorter reaction times to features appearing on a single object-apply to recently viewed novel shapes. One experiment shows that object attention operates even when the visible fragments correspond to objects that violate standard completion heuristics. Other experiments show that experience-dependent object benefits can apply to fragments even without evidence of occlusion. These results attest to the flexible operation of the perceptual system, adapting as a function of experience.

Journal of Experimental Psychology: Human Perception & Performance, 2003

The authors studied 2 patients, S.M. and R.N., to examine perceptual organization and its relationship to object recognition. Both patients had normal, low-level vision and performed simple grouping operations normally but were unable to apprehend a multielement stimulus as a whole. R.N. failed to derive global structure even under optimal stimulus conditions, was less sensitive to grouping by closure, and was more impaired in object recognition than S.M. These findings suggest that perceptual organization involves a multiplicity of processes, some of which are simpler and are instantiated in lower order areas of visual cortex (e.g., collinearity). Other processes are more complex and rely on higher order visual areas (e.g., closure and shape formation). The failure to exploit these latter configural processes adversely affects object recognition. Perceptual Organization: A Multiplicity of Processes The Gestalt psychologists suggested that perceptual organization is achieved by grouping elements together by virtue of certain properties that are present in the image. In the seminal work of Wertheimer (1923/1950) and in the follow-up by Koehler (1928), the different heuristics underlying grouping have been enumerated, and they are now commonly listed in textbooks on perception. These heuristics include grouping by proximity, by closure, by similarity, by good continuation, and by common fate. Recently, Palmer (2001; Palmer & Rock, 1994) added two more heuristics: grouping by common region and grouping by connectedness. Despite the cataloguing and the widespread acceptance of these different grouping principles, many, although not all, theories of visual perception have treated perceptual organization as a unitary phenomenon that operates at a single, early, preattentive stage, in a bottom-up fashion, to create units which then serve as candidate objects for later and more elaborated processing, including object recognition and identification (Marr, 1982; Neisser, 1967; Treis-Authorship on this article is assigned alphabetically, and the work reflects an equal contribution by both authors.

Recent research shows that, under certain conditions, visual attention is object-based. That is, attention preferentially selects objects in the visual field. These objects are processed, culminating in object recognition. On this formulation, the objects selected by attention are perceptual groups determined by the principles of perceptual organization of Gestalt psychology. These groups are formed independently of attentional processes and conceptual knowledge. This view is not consistent with available data about the visual system, which shows that perceptual organization is sensitive to conceptual information, depends on attentional processes, and infers representations that best explain the visual stimulus. Here, I propose a new account of visual attention that aims to correct these limitations of the Gestalt-based formulation. The nature of the object representations underlying perceptual and attentional mechanisms is discussed. It is proposed that attention and perception int...