Gestalt principles in the control of motor action.

We argue that 4 fundamental gestalt phenomena in perception apply to the control of motor action. First, a motor gestalt, like a perceptual gestalt, is holistic in the sense that it is processed as a single unit. This notion is consistent with reaction time results indicating that all gestures for a brief unit of action must be programmed prior to initiation of any part of the movement. Additional reaction time results related to initiation of longer responses are consistent with processing in terms of a sequence of indivisible motor gestalts. Some actions (e.g., many involving coordination of the hands) can be carried out effectively only if represented as a unitary gestalt. Second, a perceptual gestalt is independent of specific sensory receptors, as evidenced by perceptual constancy. In a similar manner a motor gestalt can be represented independently of specific muscular effectors, thereby allowing motor constancy. Third, just as a perceptual pattern (e.g., a Necker cube) is exclusively structured into only 1 of its possible configurations at any moment in time, processing prior to action is limited to 1 motor gestalt. Fourth, grouping in apparent motion leads to stream segregation in visual and auditory perception; this segregation is present in motor action and is dependent on the temporal rate. We discuss congruence of gestalt phenomena across perception and motor action (a) in relation to a unitary perceptual–motor code, (b) with respect to differences in the role of awareness, and (c) in conjunction with separate neural pathways for conscious perception and motor control. (PsycINFO Database Record (c) 2011 APA, all rights reserved)     

The role of occlusion in the perception of depth, lightness, and opacity.

A theory is presented that explains how the visual system infers the lightness, opacity, and depth of surfaces from stereoscopic images. It is shown that the polarity and magnitude of image contrast play distinct roles in surface perception, which can be captured by 2 principles of perceptual inference. First, a contrast depth asymmetry principle articulates how the visual system computes the ordinal depth and lightness relationships from the polarity of local, binocularly matched image contrast. Second, a global transmittance anchoring principle expresses how variations in contrast magnitudes are used to infer the presence of transparent surfaces. It is argued that these principles provide a unified explanation of how the visual system computes the 3-D surface structure of opaque and transparent surfaces. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Is visual imagery really visual? Overlooked evidence from neuropsychology.

Does visual imagery engage some of the same representations used in visual perception? The evidence collected by cognitive psychologists in support of this claim has been challenged by three types of alternative explanation: Tacit knowledge, according to which subjects use nonvisual representations to simulate the use of visual representations during imagery tasks, guided by their tacit knowledge of their visual systems; experimenter expectancy, according to which the data implicating shared representations for imagery and perception is an artifact of experimenter expectancies; and nonvisual spatial representation, according to which imagery representations are partially similar to visual representations in the way they code spatial relations but are not visual representations. This article reviews previously overlooked neuropsychological evidence on the relation between imagery and perception, and discusses its relative immunity to the foregoing alternative explanations. This evidence includes electrophysiological and cerebral blood flow studies localizing brain activity during imagery to cortical visual areas, and parallels between the selective effects of brain damage on visual perception and imagery. Because these findings cannot be accounted for in the same way as traditional cognitive data using the alternative explanations listed earlier, they can play a decisive role in answering the title question. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Integrating art historical, psychological, and neuroscientific explanations of artists' advantages in drawing and perception.

Art historians, artists, psychologists, and neuroscientists have long asserted that artists perceive the world differently than nonartists. Although empirical research on the nature and correlates of skilled drawing is limited, the available evidence supports this view: artists outperform nonartists on visual analysis and form recognition tasks and their perceptual advantages are correlated with and can be largely accounted for by drawing skill. The authors propose an integrative model to explain these results, derived from research in psychology and cognitive neuroscience on how category knowledge, attention, and motor plans influence visual perception. The authors claim that (a) artists' specialized, declarative knowledge of the structure of objects' appearances and (b) motor priming achieved via proceduralization and practice in an artistic medium both contribute to attention-shifting mechanisms that enhance the encoding of expected features in the visual field and account for artists' advantages in drawing and visual analysis. Suggestions for testing the model are discussed. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Gestalt psychology today.

The background of gestalt psychology is traced and relationships of gestalt psychology to physics are indicated. The notion of insight is reformulated. Certain trends in American psychology are not fully approved: "I doubt whether it is advisable to regard caution and a critical spirit as the virtues of a scientist, as though little else counted… . Too many young psychologists, it seems to me, either work only against something done by others or merely vary slightly what others have done before." Human experience in the phenomenological sense requires study. A gestalt view of motivation is presented "in terms of… forces which operate between certain perceptual processes and processes in another part of the brain, where a need may be physiologically represented." With de?mphasis on differences in Behaviorist and Gestalt schools and more emphasis on positive contributions of each, constructive work can be accomplished together. "It would be an extraordinary experience—and one good for psychology." (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Intact visual imagery and impaired visual perception in a patient with visual agnosia.

Although it is now well accepted that visual mental imagery and visual perception share common underlying mechanisms, there are several reports in which they are dissociated. Evidence for the separability of these processes is provided by a 33-yr-old male patient who has a profound visual object recognition deficit attributable to an impairment in grouping or segmenting visual images. Despite this perceptual deficit, the patient was able to draw objects in considerable detail from memory, and his knowledge of the visual appearance of objects was preserved on a variety of mental imagery tasks. Together with previous cases, these findings confirm the double dissociation between object recognition and perception. Interestingly, the patient could also recognize newly constructed objects in his internal imagery. To accommodate these results, the authors propose a model in which imagery and perception are strongly associated but are also functionally specialized. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

The status of the minimum principle in the theoretical analysis of visual perception.

Examines recent empirical investigations into minimum tendencies (MTs) in the visual perception of form, depth, and motion for purposes of comparison and evaluation, explores the theoretical status of MTs and proposed minimum principles (MPs) using systematic analysis, and considers the chief types of process models proposed to account for minimization. An MT is a psychophysical finding that perception tends toward simplicity, as measured in accordance with a specified metric. An MP is a theoretical construct imputed to the visual system to explain MTs. The notion that simple perceptual representations must be defined within the "geometric constraints" provided by proximal stimulation is examined, as are the metrics of simplicity. It is contended that any study of perceptual economy must use a metric of simplicity; the choice of metric may be seen as a matter of convention or it may have deep theoretical and empirical implications. Several answers to the question of why the visual system might favor economical representations are evaluated. Several accounts of the process for achieving perceptual economy are examined, and it is concluded that those that favor massively parallel processing are the most plausible. (99 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

When writing impairs reading: Letter perception’s susceptibility to motor interference.

The effect of writing on the concurrent visual perception of letters was investigated in a series of studies using an interference paradigm. Participants drew shapes and letters while simultaneously visually identifying letters and shapes embedded in noise. Experiments 1–3 demonstrated that letter perception, but not the perception of shapes, was affected by motor interference. This suggests a strong link between the perception of letters and the neural substrates engaged during writing. The overlap both in category (letter vs. shape) and in the perceptual similarity of the features (straight vs. curvy) of the seen and drawn items determined the amount of interference. Experiment 4 demonstrated that intentional production of letters is not necessary for the interference to occur, because passive movement of the hand in the shape of letters also interfered with letter perception. When passive movements were used, however, only the category of the drawn items (letters vs. shapes), but not the perceptual similarity, had an influence, suggesting that motor representations for letters may selectively influence visual perception of letters through proprioceptive feedback, with an additional influence of perceptual similarity that depends on motor programs. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Dissociated overt and covert recognition as an emergent property of a lesioned neural network.

Covert recognition of faces in prosopagnosia, in which patients cannot overtly recognize faces but nevertheless manifest recognition when tested in certain indirect ways, has been interpreted as the functioning of an intact visual face recognition system deprived of access to other brain systems necessary for consciousness. The authors propose an alternative hypothesis: that the visual face recognition system is damaged but not obliterated in these patients and that damaged neural networks will manifest their residual knowledge in just the kinds of tasks used to measure covert recognition. To test this, a simple model of face recognition is lesioned in the parts of the model corresponding to visual processing. The model demonstrates covert recognition in 3 qualitatively different tasks. Implications for the nature of prosopagnosia, and for other types of dissociations between conscious and unconscious perception, are discussed. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Visual and spatial perception in the early phase of Alzheimer's disease.

A battery of visuospatial perception tests was administered to 27 mild probable Alzheimer's disease (AD) patients; 21 were reassessed after 8 months. At the first evaluation, AD patients were impaired only in an object-naming task. After 8 months, the performance in the subtests of object perception was unchanged, while there was a significant decline in the total score of the items tapping space perception. A significant worsening was also observed in the Rey's figure copy score and was correlated with the decrease in the spatial perception score. This study confirms that an impairment in visual perceptual tests requiring access to semantic and lexical knowledge is present in the earliest phase of AD, whereas visuospatial and constructional impairments became evident only later. This pattern of progression may represent the clinical correlate of increasing pathological involvement of posterior associative cortex. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Picture perception and monocular vision: a reply to Hagen

It is argued that M. A. Hagen's (see record 1975-00215-001) review of picture perception contains a number of inaccuracies involving the nature of higher order variables in perception, the demonstration of visual compensation, the manipulation of relative size information, the postulation of an ability to discriminate the correctness of viewing point, and the existence of ambiguity in monocular perception. It is suggested that such errors are the result of a misunderstanding of the formal basis of J. J. Gibson's (1950, 1966) perceptual theory. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Perspectives and transformations.

Addresses the idea of understanding visual perception (VP) and the philosophical dilemma of examining such an experience. It is argued that even though VP is well accommodated to the practical exigencies of the world, it is not too epistemological a topic for psychologists to address. Discussion focuses on the history of research on VP, beginning with the issue of stimulus equivalence and emphasizing the perceptual adaptation strategies and resulting perceptual transformations of the visual system. Following an overview of D. H. Hubel and T. N. Wiesel's (1962) research on single unit recording in the visual cortex, newer perspectives, such as W. C. Hoffman's (1978) lie transformation group model of neuropsychology and the McCollough effect (C. McCollough, 1965), are presented. New research by the author is discussed that deals with (1) representation and reality and (2) explanation and prediction in psychology. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Severe mental retardation among children in the county of Arhus, Denmark. A community study on prevalence and provision of service

(1) We have used both subjective and evoked potential tests to study cases of multiple sclerosis with no history of retrobulbar neuritis (spinal patients) and compared them with patients with multiple sclerosis who had experienced an attack of retrobulbar neuritis (RBN). We measured the delay of steady-state evoked potentials (EPs) elicited by flicker in the medium-frequency (13-25 c/s) range, by flicker in the high-frequency (30-60 c/s) range, and by pattern-reversal. We also measured the delay in seeing (perceiving) both an increase of light intensity and a decrease of light intensity. (2) The difference between perceptual delays for the left and right eyes (D s) was abnormal when retrobulbar neuritis affected only one eye (22/22 patients) even when acuity and discs were normal. It might be supposed that this perceptual test would be ineffective when both eyes were affected by retrobulbar neuritis. However, the value of D was abnormal in cases of bilateral retrobulbar neuritis (5/5 patients). Probably the principal reason is that demyelination was patchy in the patients studied. For this same reason the difference between perceptual delays for two sites in the visual field (T s) may also be abnormal. In principle the perceptual delay test can be effective even when both eyes are similarly delayed: abnormal values of T were recorded in 5 spinal patients for whom D was normal. (3) Perceptual delays were measured for an extended group of 19 patients suffering from spinal multiple sclerosis. Taking both D and T into account, the perceptual delay test alone picked out 12/19 spinal patients. The perceptual delay test has the advantage over EP tests that it can detect islands of demyelination as small as 3 degrees diameter, and the apparatus is cheap and straightforward to use. (4) Thirteen patients with spinal multiple sclerosis, including 6 with no ocular signs or symptoms, were examined with a battery of two evoked potential and one perceptual test. Ten patients had clearly abnormal visual delays. Results for the remaining 3 were equivocal. Delay tests can reveal visual damage in most patients who have not experienced an attack of RBN as well as in practically all patients who have experienced an attack. (5) Correlations between the results of the various tests were different in spinal patients and in multiple sclerosis patients who had experienced an attack of retrobulbar neuritis. Flicker EPs, pattern EPs and visual perception were all delayed in every RBN patient, whereas for spinal patients different tests could pick up different patients. Flicker EPs picked up 5/13 spinal patients, pattern EPs 6/13, perceptual delay (D) picked up 4/13 and perceptual delay T picked up 7/13. (6) Delay tests divided spinal multiple sclerosis patients into two fairly distinct groups. In one group pattern EPs and perception were delayed; in the other group flicker EPs were delayed. This grouping corresponded to a clinical distinction between long-standing patients with visual signs and recent patients without visual signs...     

A little bit louder now: Negative affect increases perceived loudness.

Traditionally, perception was considered to be an encapsulated process that was unaffected by top-down processes like affect. Recent work in vision draws this framework into question by showing that changes in the affective state of the perceiver can impact many different aspects of visual perception. Here, we extend the relationship between affect and perception into another perceptual modality: audition. Participants were induced into a negative or neutral mood by writing about a frightening or neutral experience in their past. They then listened to a series of short, neutral tones (320 and 640 ms) and rated the loudness and duration of the tones. Participants in a negative mood rated the tones as significantly louder, but not longer, than participants in a neutral mood, suggesting that the difference between the groups was perceptual rather than just a response bias. This research shows for the first time that the role of affect in perceptual processes may be more pervasive than previously considered. (PsycINFO Database Record (c) 2011 APA, all rights reserved)     

Eleanor J. Gibson: Learning to perceive and perceiving to learn.

E. Gibson essentially defined the domain of perceptual learning, which includes both improvement in perception as a function of experience and learning and acquisition of knowledge as a function of changes in perception. In her view, differentiation, as opposed to association, is the process underlying perceptual development as well as perceptual learning. She considered perceptual development to be an important aspect of cognitive development. To a considerable degree, children's acquisition of knowledge and their increasingly complex conceptual sophistication can be attributed to their ability to detect more and more meaningful aspects of the rich stimulation impinging on them. This theoretical analysis was instantiated in empirical research on a wide range of topics. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

The theory of multistage integration in the visual brain

The theory of multistage integration is based on evidence that the visual brain consists of several parallel multistage processing systems, each specialized for a given attribute such as colour or motion. Each stage of a given system processes information at a distinct level of complexity. Our theory supposes that activity at any stage of a given multistage processing system is perceptually explicit--that is to say, it requires no further processing to generate a conscious experience. This activity can be integrated, or bound, with the perceptually explicit activity at any given stage of another or the same multistage processing system. Such binding is therefore not a process that generates a conscious experience, but rather one that brings different conscious experiences together. Many perceptual advantages result from such a flexible and dynamic integrative system. Conversely, there would be disadvantages to limiting perception and binding to hypothetical 'terminal' stages of such processing systems or to hypothetical 'integrator' areas. Although we formulate our hypothesis in terms of the visual brain, we believe it might form a general principle of brain functioning.     

Selective attention and the acquisition of new phonetic categories.

A class of selective attention models often applied to speech perception is used to study effects of training on the perception of an unfamiliar phonetic contrast. Attention-to-dimension (A2D) models of perceptual learning assume that the dimensions that structure listeners' perceptual space are constant and that learning involves only the reweighting of existing dimensions to emphasize or de-emphasize different sensory dimensions. Multidimensional scaling is used to identify the acoustic-phonetic dimensions listeners use before and after training to recognize the 3 classes of Korean stop consonants. Results suggest that A2D models can account for some observed restructuring of listeners' perceptual space, but listeners also show evidence of directing attention to a previously unattended dimension of phonetic contrast. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Coordinate transformations in object recognition.

A basic problem of visual perception is how human beings recognize objects after spatial transformations. Three central classes of findings have to be accounted for: (a) Recognition performance varies systematically with orientation, size, and position; (b) recognition latencies are sequentially additive, suggesting analogue transformation processes; and (c) orientation and size congruency effects indicate that recognition involves the adjustment of a reference frame. All 3 classes of findings can be explained by a transformational framework of recognition: Recognition is achieved by an analogue transformation of a perceptual coordinate system that aligns memory and input representations. Coordinate transformations can be implemented neurocomputationally by gain (amplitude) modulation and may be regarded as a general processing principle of the visual cortex. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Intact perceptual memory in the absence of conscious memory.

Declarative memory enables conscious recollection of the past and has been proposed to be distinct from priming, a perceptual form of memory that operates nonconsciously and improves the ability to detect or identify recently presented stimuli. Yet, it has been difficult to obtain unambiguous evidence for the independence of declarative memory and priming. The authors report the first demonstration, using matched tests, of fully intact perceptual memory (priming) in a profoundly amnesic patient (E.P.), despite at-chance recognition memory. The priming and recognition tests included tests that were matched with respect to test materials, length of the study and test lists, and the kind of cues available at test. Priming appears to reflect neural changes within perceptual processing systems that occur before information reaches the brain systems that transform visual perception into conscious visual memory. (PsycINFO Database Record (c) 2010 APA, all rights reserved)