Toward a Psychophysics of Perceptual Organization Using Multistable Stimuli and Phenomenal Reports

We explore experimental methods used to study the phenomena of perceptual organization, first studied by the Gestalt psychologists. We describe an application of traditional psychophysics to perceptual organization and offer alternative methods. Among these, we distinguish two approaches that use multistable stimuli: (1) phenomenological psychophysics, in which the observer's response is assumed to accurately and directly reflect perceptual experience; and (2) the interference paradigm, in which an observer's response is evaluated as correct or incorrect because it pertains to a corrigible task, but does not directly reflect the observer's experience. We show that phenomenological psychophysics can yield valuable information about perceptual organization and lends itself to the development of quantitative theory. We discuss some criticisms of the method and argue that the two approaches that use multistable stimuli are complementary. We also compare each of the approaches with traditional psychophysics. We conclude that the several methods are convergent.     

Directional harmonic theory: a computational Gestalt model to account for illusory contour and vertex formation

Visual illusions and perceptual grouping phenomena offer an invaluable tool for probing the computational mechanism of low-level visual processing. Some illusions, like the Kanizsa figure, reveal illusory contours that form edges collinear with the inducing stimulus. This kind of illusory contour has been modeled by neural network models by way of cells equipped with elongated spatial receptive fields designed to detect and complete the collinear alignment. There are, however, other illusory groupings which are not so easy to account for in neural network terms. The Ehrenstein illusion exhibits an illusory contour that forms a contour orthogonal to the stimulus instead of collinear with it. Other perceptual grouping effects reveal illusory contours that exhibit a sharp corner or vertex, and still others take the form of vertices defined by the intersection of three, four, or more illusory contours that meet at a point. A direct extension of the collinear completion models to account for these phenomena tends towards a combinatorial explosion, because it would suggest cells with specialized receptive fields configured to perform each of those completion types, each of which would have to be replicated at every location and every orientation across the visual field. These phenomena therefore challenge the adequacy of the neural network approach to account for these diverse perceptual phenomena. I have proposed elsewhere an alternative paradigm of neurocomputation in the harmonic resonance theory (Lehar 1999, see website), whereby pattern recognition and completion are performed by spatial standing waves across the neural substrate. The standing waves perform a computational function analogous to that of the spatial receptive fields of the neural network approach, except that, unlike that paradigm, a single resonance mechanism performs a function equivalent to a whole array of spatial receptive fields of different spatial configurations and of different orientations, and thereby avoids the combinatorial explosion inherent in the older paradigm. The present paper presents the directional harmonic model, a more specific development of the harmonic resonance theory, designed to account for specific perceptual grouping phenomena. Computer simulations of the directional harmonic model show that it can account for collinear contours as observed in the Kanizsa figure, orthogonal contours as seen in the Ehrenstein illusion, and a number of illusory vertex percepts composed of two, three, or more illusory contours that meet in a variety of configurations.     

Grouping reduces visual extinction: Neuropsychological evidence for weight-linkage in visual selection

Abstract

We tested two subjects following damage to right parietal cortex to see if their failure to detect a left visual stimulus in the presence of a simultaneous right stimulus (visual extinction) could be modulated by perceptual grouping between the left and right stimuli. Subjects performed a simple detection task for brief displays in which items could appear in the left or right visual field, both fields, or neither field. On trials in which items appeared in both fields, we found that left omissions (extinction errors) were dramatically reduced when the two items formed a good perceptual group, either on the basis of Gestalt factors such as similarity and symmetry (Experiment 1). or by forming a familiar configuration (Experiment 2). We suggest that extinction may be a spatially specific exaggeration of a normal attention limitation, in which the contralesional item is disadvantaged in the competition for selection. However, this obstacle to selection can be overcome if, as a result of grouping, ipsilesional and contralesional items become allies rather than competitors for selection.     

Dynamics of perceptual grouping: Similarities in the organization of visual and auditory groups

In vision, the Gestalt principles of perceptual organization are generally well understood and remain a subject of detailed analysis. However, the possibility for a unified theory of grouping across visual and auditory modalities remains largely unexplored. Here we present examples of auditory and visual Gestalt grouping, which share important organizational properties. In particular, similarities are revealed between grouping processes in apparent motion, auditory streaming, and static 2-D displays. Given the substantial difference in the context, within which the phenomena in question occur (auditory vs. visual, static vs. dynamic), these similarities suggest that the dynamics of perceptual organization could be associated with a common (possibly central) mechanism. If the relevance of supramodal invariants of grouping is granted, the question arises as to whether they can be studied empirically. We propose that a “force-field” theory, based on a differential-geometric interpretation of perceptual space, could provide a suitable starting point for a systematic exploration of the subjective properties of certain classes of auditory and visual grouping phenomena.     

Merleau-Ponty’s Immanent Critique of Gestalt Theory

Merleau-Ponty’s appropriation of Gestalt theory in The Structure of Behavior is central to his entire corpus. Yet commentators exhibit little agreement about what lesson is to be learned from his critique, and provide little exegesis of how his argument proceeds. I fill this exegetical gap. I show that the Gestaltist’s fundamental error is to reify forms as transcendent realities, rather than treating them as phenomena of perceptual consciousness. From this, reductivist errors follow. The essay serves not only as a helpful guide through parts of The Structure of Behavior for newcomers, but also offers a corrective to recent trends in philosophy of mind. Such influential commentators as Hubert Dreyfus, Taylor Carmen, and Evan Thompson have, I argue, risked serious misunderstanding of Merleau-Ponty’s view, by mistakenly treating “circular causality” as central to Merleau-Ponty’s own acausal (dialectical) view of forms.     

Some new gestalt psychologies

Summary The present decade has seen a resurgence of interest in perceptual phenomena investigated by Gestalt psychologists. Some of these new psychologies call themselves Neo-Gestalt psychology. Thus it seems appropriate to examine their relation to Gestalt psychology.In addition to the problems they investigate, these new psychologies usually have in common an information-processing approach to perception. Thus information processing is compared with Gestalt psychology; the major issues to be considered are mechanism and atomism. In addition, a brief discussion of phenomenology is seen to be relevant to these new psychologies, quite apart from their relation to information processing. After a short discussion of these major issues, a still briefer examination of a few Neo-Gestalt psychologies and of the parallel distributed processing (PDP) approach is undertaken.This paper is a condensed and reorganized version of a chapter to be included in a forthcoming Festschrift for Solomon Asch, edited by Irvin Rock     

Subliminal Gestalt grouping: Evidence of perceptual grouping by proximity and similarity in absence of conscious perception

Previous studies making use of indirect processing measures have shown that perceptual grouping can occur outside the focus of attention. However, no previous study has examined the possibility of subliminal processing of perceptual grouping. The present work steps forward in the study of perceptual organization, reporting direct evidence of subliminal processing of Gestalt patterns. In two masked priming experiments, Gestalt patterns grouped by proximity or similarity that induced either a horizontal or vertical global orientation of the stimuli were presented as masked primes and followed by visible targets that could be congruent or incongruent with the orientation of the primes. The results showed a reliable priming effect in the complete absence of prime awareness for both proximity and similarity grouping principles. These findings suggest that a phenomenal report of the Gestalt pattern is not mandatory to observe an effect on the response based on the global properties of Gestalt stimuli.     

The perceptual organization of dot lattices

Bravais (1850/1949) demonstrated that there are five types of periodic dot patterns (or lattices): oblique, rectangular, centered rectangular, square, and hexagonal. Gestalt psychologists studied grouping by proximity in rectangular and square dot patterns. In the first part of the present paper, I (1) describe the geometry of the five types of lattices, and (2) explain why, for the study of perception, centered rectangular lattices must be divided into two classes (centered rectangular andrhombic). I also show how all lattices can be located in a two-dimensional space. In the second part of the paper, I show how the geometry of these lattices determines their grouping and their multistability. I introduce the notion ofdegree of instability and explain how to order lattices from most stable to least stable (hexagonal). In the third part of the paper, I explore the effect of replacing the dots in a lattice with less symmetric motifs, thus creating wallpaper patterns. When a dot pattern is turned into a wallpaper pattern, its perceptual organization can be altered radically, overcoming grouping by proximity. I conclude the paper with an introduction to the implications of motif selection and placement for the perception of the ensuing patterns.     

Pavlov and the demise of the influence of Gestalt psychology in the Soviet Union

Summary The demise of the influence of the classical Gestalt psychology in the Soviet Union has been linked to I.P. Pavlov's negative stance toward Gestalt tenets. Actually, Pavlov's attitude toward Gestalt psychology was by no means uniform. Pavlov was receptive to, as well as critical of a number of substantive issues. He acknowledged the Gestalt interpretation of transposition, but criticized the Gestalt rejection of association and learning by trial and error. Pavlov's strongest objection to Gestalt psychology centered on the philosophical issues of causality, methodology, and on the problem of mind and body. Despite these objections, no direct evidence links Pavlov's criticism of Gestalt theses to the weakening of their influence on Soviet psychology. Instead, the demise of classical Gestalt psychology in the Soviet Union should be attributed to political exigency. Soviet authorities, in a period of political crises, were intent upon the elimination of all traces of bourgeois psychologies.     

Phenomenal Causality II: Integration and Implication

The empirical literature on phenomenal causality (the notion that causality can be perceived) is reviewed. Different potential types of phenomenal causality and variables that influence phenomenal causality were considered in Part I (Hubbard 2012b) of this two-part series. In Part II, broader questions regarding properties of phenomenal causality and connections of phenomenal causality to other perceptual or cognitive phenomena (different types of phenomenal causality, effects of spatial and temporal variance, phenomenal causality in infancy, effects of object properties, naïve physics, spatial localization, other illusions, amodal completion, Gestalt principles of perceptual grouping, effects of context, differences between physical and social causality, effects of learning and experience, individual differences, effects of predictability, asymmetry in phenomenal causality, differences between perceived causality and perceived force, phenomenal causality in nonhuman animals) are considered. Potential mechanisms of phenomenal causality (inference from contiguity, a priori understanding, ampliation, perceptual learning, stimulus activity, beliefs regarding kinematics, haptic experience, beliefs regarding impetus, postdiction, innateness, modularity, specific neural structures) are also considered.     

Gestalt Psychology as a Missing Link in Ernst Cassirer’s Mythical Symbolic Form

The main goal of this article is to investigate the mythical symbolic form in Cassirer’s Philosophy of Symbolic Form regarding its connection with visual perception. The article argues that mythical symbolic form is rooted in Gestalt principles of perception for organizing the perceptual field, and shows that these principles shape the main features of space and time in Cassirer’s mythical symbolic form. This argument challenges Heidegger’s critique of Cassirer’s definition of a mythical symbolic form that it is directionless and not grounded in man’s being. The combination of Gestalt principles and mythical symbolic forms supports the argument about the active role of visual perception, and clarifies Cassirer’s application and re-definition of Kantian and Neo-Kantian concepts. The investigation opens a perspective for comprehending the mythic-religious phenomenon as well as for comprehending visual perception.     

GROUPING BY PROXIMITY AND MULTISTABILITY IN DOT LATTICES:

Abstract— Gestalt phenomena have long resisted quantification. In the spirit of Gestalt field theory, we propose a theory that predicts the probability of grouping by proximity in the six kinds of dot lattices (hexagonal, rhombic, square, rectangular, centered rectangular, and oblique). We claim that the unstable perceptual organization of dot lattices is caused by competing forces that attract each dot to other dots in its neighborhood. We model the decline of these forces as a function of distance with an exponential decay function. This attraction function has one parameter, the attraction constant Simple assumptions allow us to predict the entropy of the perceptual organization of different dot lattices. We showed dot lattices tachistoscopically to 7 subjects, and from the probabilities of the perceived organisations, we calculated the entropy of each lattice for each subject. The model fit the data exceedingly well. The attraction constant did not vary much over subjects     

The Gestalt principle of similarity benefits visual working memory

Visual working memory (VWM) is essential for many cognitive processes, yet it is notably limited in capacity. Visual perception processing is facilitated by Gestalt principles of grouping, such as connectedness, similarity, and proximity. This introduces the question, do these perceptual benefits extend to VWM? If so, can this be an approach to enhance VWM function by optimizing the processing of information? Previous findings have demonstrated that several Gestalt principles (connectedness, common region, and spatial proximity) do facilitate VWM performance in change detection tasks (Jiang, Olson, & Chun, 2000; Woodman, Vecera, & Luck, 2003; Xu, 2002, 2006; Xu & Chun, 2007). However, one prevalent Gestalt principle, similarity, has not been examined with regard to facilitating VWM. Here, we investigated whether grouping by similarity benefits VWM. Experiment 1 established the basic finding that VWM performance could benefit from grouping. Experiment 2 replicated and extended this finding by showing that similarity was only effective when the similar stimuli were proximal. In short, the VWM performance benefit derived from similarity was constrained by spatial proximity, such that similar items need to be near each other. Thus, the Gestalt principle of similarity benefits visual perception, but it can provide benefits to VWM as well.     

Rethinking perceptual organization: The role of uniform connectedness

A principle of perceptual organization, calleduniform connectedness (UC), is described, and a theoretical approach to perceptual organization is proposed in which this principle plays a fundamental role. The principle of UC states that closed regions of homogeneous properties—such as lightness, chromatic color, texture, and so forth—tend to be perceived initially as single units. We demonstrate its effects and show that they occur even when opposed by powerful grouping principles such as proximity and similarity. We argue that UC cannot be reduced to such grouping principles, because it is not a form of grouping at all. We then propose a theoretical framework within which UC accounts for the initial (orentry level) organization of the visual field into primitive units. Classical principles of grouping operate after UC, creating superordinate units consisting of two or more basic-level units. Parsing processes also operate after UC, dividing basic-level units into subordinate parts. UC in the retinal image is proposed to be a necessary, but not a sufficient, condition for unit formation, since connected elements on the retina that are perceived to lie in separate depth planes fail to be perceived as units. This fact, together with other evidence that the Gestalt principles of grouping are based onperceived (rather than retinal) relations, suggests that the organization of visual stimulation into UC objects is ultimately achieved within a relatively late, postconstancy representation of environmental surfaces. The implications of this possibility are discussed in light of present theories of visual perception.     

Teaching a picture language to a non-speaking retarded boy

In recent years numerous operant language training programmes have been designed for teaching both receptive and expressive language to autistic and retarded children (e.g. Bricker and Bricker. 1970a; Bricker and Bricker, 1970b; Lovaas, 1968; Sloane et al, 1968). There have been suggestions that the content of such programmes should be to some extent dictated by the findings of psycholinguists, while the methods be designed along behaviour modification lines (Lynch and Bricker, 1972; Miller and Yoder, 1972). Certainly operant programmes have been shown to produce some improvement of language function in autistic and retarded children (Bricker and Bricker. 1970a; Sloane et al, 1968; Lovaas. 1968; Guesset al, 1968); but the problem of whether all retarded children can be taught some language by these means has not been tackled. Psycholinguists, following Chomsky (Chomsky, 1965) maintain that the development of language in children is dependent on the language acquisition device, or LAD. Unfortunately there are no independent means of determining the presence of LAD in a child, so that relating a child's inability to use language to the absence of LAD becomes a circular argument.It frequently seems to be assumed that, provided no perceptual deficits are present, language acquisition is as difficult in one medium as in another. Individuals who are deaf and retarded have been taught sign language with some success (Berger, 1972; Cornforth et al, 1974), and retarded children who are non-speaking have been taught symbolic languages (Bliss symbols in Vanderheiden et al, 1975; Premack symbols in Hollis and Carrier, 1975, and Hodges, 1976). It is unclear, however, whether those learning symbolic languages, but having no gross physical or perceptual handicap, could have learnt sign language or even spoken language with an equivalent method of training. The present study is a report of a retarded boy with unreliable hearing (which ruled out spoken language), who seemed unable to learn (receptive or expressive) sign language after extensive operant training, but who rapidly acquired a limited symbolic “language” using an identical training method. The symbols used were pictorial representations of the objects (cf. Bliss and Premack symbols).     

Visual attention and perceptual grouping

Perceptual organization is thought to involve an analysis of bothtextural discontinuities andperceptual grouping. In earlier work, we found that textural discontinuities were detected normally even when visual attention was engaged elsewhere. Here we report how perceptual grouping is affected when visual attention is engaged by a concurrent visual task. To elicit perceptual grouping, we used the Gestalt demonstrations of grouping on the basis of proximity and of similarity. Four tasks were investigated, some requiring the observer to discriminate between horizontal and vertical grouping, and some requiring the observer to merely detect the presence or absence of grouping. Visual attention was engaged at the center of the display by a form identification task. The detection of a textural discontinuity served as a control task. Concurrent form identification conflicted with all four grouping tasks, resulting in a significant reduction of grouping performance in each case. No performance reduction was observed when either form identification or grouping discrimination was combined with the detection of a textural discontinuity. These results suggest that perceptual grouping and form identification compete for visual attention, whereas the detection of a textural discontinuity does not.     

Husserl’s appropriation of the psychological concepts of apperception and attention

In the sixth Logical Investigation, Husserl thematizes the surplus (Überschuß) of the perceptual intention whereby the intending goes beyond the partial givenness of a perceptual object to the object as a whole. This surplus is an apperceptive surplus that transcends the purely perceptual substance (Gehalt) or sensed content (empfundene Inhalt) available to a perceiver at any one time. This surplus can be described on the one hand as a synthetic link to future, possible, active experience; to intend an object is to intend it as it would appear if we were to have an exhaustively synthetic explication of it. This perceptual apperceptive surplus is, on the other hand, distinguished from the surplus that categorial form represents over the perceptual sense data. In this paper I show how the apperceptive surplus can also be understood as a synthetic link to past experience that is passively operative in any present perception. The synthetic link to both past and possible experience is a link to non-actual perceptions. Links to non-actual experience are despite their non-actuality nevertheless genuinely intentional in that they enter into the sense of any actively constituted object understood as a unity of sense. Key to this interpretation is an explanation of how Husserl appropriated the key concepts of attention and apperception from psychologists of his day, such as Stumpf and Wundt.     

From elements to perception: local and global processing in visual neurons

Gestalt psychologists in the early part of the century challenged psychophysical notions that perceptual phenomena can be understood from a punctate (atomistic) analysis of the elements present in the stimulus. Their ideas slowed later attempts to explain vision in terms of single-cell recordings from individual neurons. A rapprochement between Gestalt phenomenology and neurophysiology seemed unlikely when the first ECVP was held in Marburg, Germany, in 1978. Since that time, response properties of neurons have been discovered that invite an interpretation of visual phenomena (including illusions) in terms of neuronal processing by long-range interactions, as first proposed by Mach and Hering in the last century. This article traces a personal journey into the early days of neurophysiological vision research to illustrate the progress that has taken place from the first attempts to correlate single-cell responses with visual perceptions. Whereas initially the receptive-field properties of individual classes of cells--e.g., contrast, wavelength, orientation, motion, disparity, and spatial-frequency detectors--were used to account for relatively simple visual phenomena, nowadays complex perceptions are interpreted in terms of long-range interactions, involving many neurons. This change in paradigm from local to global processing was made possible by recent findings, in the cortex, on horizontal interactions and backward propagation (feedback loops) in addition to classical feedforward processing. These mechanisms are exemplified by studies of the tilt effect and tilt aftereffect, direction-specific motion adaptation, illusory contours, filling-in and fading, figure--ground segregation by orientation and motion contrast, and pop-out in dynamic visual-noise patterns. Major questions for future research and a discussion of their epistemological implications conclude the article.     

Perceptual wholes can reduce the conscious accessibility of their parts

Humans can rapidly extract object and category information from an image despite surprising limitations in detecting changes to the individual parts of that image. In this article we provide evidence that the construction of a perceptual whole, or Gestalt, reduces awareness of changes to the parts of this object. This result suggests that the rapid extraction of a perceptual Gestalt, and the inaccessibility of the parts that make up that Gestalt, may in fact reflect two sides of the same coin whereby human vision provides only the most useful level of abstraction to conscious awareness.