Showing papers on "Visual perception published in 1981"

Young children's knowledge about visual perception: Further evidence for the Level 1–Level 2 distinction.

Abstract: Three studies were done to test the hypothesis that there is a development in early childhood from a less advanced (Level 1) to a more advanced (Level 2) form of knowledge and thinking about people's visual experiences. Study 1 replicated and further validated a previous finding that 3-year-olds perform very well on tasks that call for Level 1 knowledge but very poorly on those that require Level 2 knowledge. Study 2 showed that children of this age did not perform better when critical aspects of Level 2 tasks were designed to be familiar to them and similar to what they might encounter in everyday life. Study 3 showed that most of the children who performed poorly on Level 2 tasks in Study 2 continued to perform poorly on a retest given 2-19 weeks later. In addition, a brief training period following the retest proved largely unsuccessful in inducing Level 2 knowledge and thinking in these children. The results of these three studies appear to provide strong support for the Level 1-Level 2 developmental hypothesis.

Inferotemporal neurons distinguish and retain behaviorally relevant features of visual stimuli

Abstract: Single-cell activity was recorded in the inferotemporal cortex of monkeys performing a task that requires perception and temporary retention of colored stimuli. Many cells reacted differentially to the stimuli. By changing the relevance of certain features of compound stimuli, it was found that the reactions of some cells to color depend critically on whether or not the task demands that the animal pay attention to color. A substantial number of cells showed color-dependent differences in frequency of discharge during the retention periods of the task. The temporal characteristics of differential discharge and its dissolution when memory is no longer required indicate that the cells that display it are involved in retaining visual information.

From Images to Surfaces: A Computational Study of the Human Early Visual System

Abstract: Based on the author's thesis (Ph.D.--Massachusetts Institute of Technology) Includes indexes.

The functional properties of the light-sensitive neurons of the posterior parietal cortex studied in waking monkeys: foveal sparing and opponent vector organization.

Abstract: We describe in this paper the results of a new study of the inferior parietal lobule in 10 waking monkeys combining the methods of behavioral control, visual stimulation, and single neuron analysis. In this study, 1682 neurons were identified; 804 were studied in detail. Neurons insensitive to visual stimuli comprise the fixation, oculomotor, and projection-manipulation classes thought to be involved in initiatives toward action. The largest group of the light-sensitive (LS) neurons were activated from large and frequently bilateral response areas that excluded the foveal region; we term this foveal sparing. The remaining cells subtended areas including the fovea, when tested with large stimuli (6 degrees X 6 degrees), but only 8 of 216 cells studied in detail responded to the small fixation target light. We propose that a dynamic central neural process associated with the acts of fixation and visual attention suppresses responses to foveal stimuli. Parietal LS neurons are sensitive to stimulus movement and direction over a wide range of velocities. The vectors point either inward toward the center or outward toward the perimeter of the visual field, and for neurons with bilateral response areas, the vectors commonly point in opposite directions in the two half-fields; we term this opponent vector organization. The functional properties of area 7 LS neurons are such that they could signal motion in the immediate surround and the apparent motion accompanying head movements and forward locomotion. We surmise that they contribute to a central neural image of immediately surrounding space and to the perceptual constancy of that space obtaining during bodily movement. These properties are suitable for the attraction of gaze and attention to objects and events in the peripheral visual fields. It is this system, together with the classes of parietal neurons concerned with action initiatives, whose destruction is thought to account for the hemi-inattention and neglect of the parietal lobe syndrome in primates.

Visual perception of lifted weight.

Abstract: The weight of a box can be seen by observing another person lifting and carrying it. Evidence is provided in two experiments, the first of which employed videotaped events with the actor and box visible only as 21 bright patches. Observers judged the weight of the box rather linearly with an average slope of .87 and with a pooled standard deviation of 3.8 kg. The second experiment compared visual and haptic perception of box weight in similar events under conditions of live action. Average slopes of 1.00 in the visual mode and 1.20 in the haptic mode were obtained with standard deviations of 3.1 kg and 2.0 kg, respectively. It is concluded that the weight of the box, as a dynamic variable of the event, is well specified in the kinematic pattern and hence in the optic array. Furthermore, the visual system is efficient in picking up such information.

Processing visual feedback information for movement control.

Abstract: The time needed to process visual feedback information for the control of aimed movements was investigated. Experiment 1 demonstrated that withdrawing visual feedback information from the initial portions of aiming responses had little effect on movement outcome. This finding suggested that visual processing times may be faster than previous estimates. The vision manipulation paradigm employed in Experiment 1 was combined with high-speed cinematography. Examination of movement patterns indicated that the average time between the presentation of visual error information and the initiation of a movement correction was 135 msec. The findings from these two experiments support the contention that the time needed to process visual error information and to use this information for movement control is shorter than previous estimates of 190 to 300 msec.

The Ferrier Lecture, 1980: Critical Limiting Factors in the Design of the Eye and Visual Cortex

Abstract: The main factors limiting the performance of the peripheral parts of the visual system can be specified, and doing this clarifies the nature of the interpretive tasks that must be performed by the central parts of the system. It is argued that the critical factor that hinders development of better resolving power is the difficulty of confining light within the waveguide-like outer segment, and that for sensitivity this critical factor is the thermal decomposition of photosensitive pigments. Knowledge of these limits makes many surprising details of the eye intelligible. Understanding the difficulties posed by the narrow dynamic range of nerve fibres may give similar insight into the coding of the retinal image for transmission to the brain. Our level of understanding changes when we come to the visual cortex, for although we do not lack good anatomical and neurophysiological data, these do not make the principles of operation self-evident in the way that the structure of the eye immediately suggests that it is an image-forming device. The cortex converts the representation of the visual field that it receives into reliable knowledge of the world around us, and the trouble may be that we lack good models of how this can be done. A system that can respond to single quanta and resolve almost to the diffraction limit is unlikely to employ grossly inefficient methods for those higher functions upon which its whole utility depends, and so it is worth seeking out the limiting factors. The quality of human performance at certain higher perceptual tasks is high compared with the limit of reliable statistical inference; hence much of the sample of information available in a visual image must be effectively utilized. But there are strong limitations on the connectivity in the cortex, so that one is forced to consider how the relevant information can be collected together. Three stages of dealing with the visual image are proposed: the improvement of the cortical map in primary visual cortex by processes analogous to spatial and temporal interpolation; the detection of linking features in this map; and the concentration of this information by non-topographical mapping in adjacent visual areas.

Metabolic mapping of the brain's response to visual stimulation: studies in humans

Abstract: These studies demonstrated increasing glucose metabolic rates in the human primary (PVC) and associative (AVC) visual cortex as the complexity of visual scenes increased. The metabolic response of the AVC increased more rapidly with scene complexity than that of the PVC, indicating the greater involvement of the higher order AVC for complex visual interpretations. Increases in local metabolic activity by as much as a factor of 2 above that of control subjects with eyes closed indicate the wide range and metabolic reserve of the visual cortex.

Principles of feature integration in visual perception

Abstract: Several recent theories of visual information processing have postulated that errors in recognition may result not only from a failure in feature extraction, but also from a failure to correctly join features after they have been correctly extracted. Errors that result from incorrectly integrating features are called conjunction errors. The present study uses conjunction errors to investigate the principles used by the visual system to integrate features. The research tests whether the visual system is more likely to integrate features located close together in visual space (the location principle) or whether the visual system is more likely to integrate features from stimulus items that come from the same perceptual group or object (the perceptual group principle). In four target-detection experiments, stimuli were created so that feature integration by the location principle and feature integration by the perceptual group principle made different predictions for performance. In all of the experiments, the perceptual group principle predicted feature integration even though the distance between stimulus items and retinal eccentricity were strictly controlled.

Influence of combined visual and vestibular cues on human perception and control of horizontal rotation

Abstract: Measurements are made of manual control performance in the closed-loop task of nulling perceived self-rotation velocity about an earth-vertical axis. Self-velocity estimation is modeled as a function of the simultaneous presentation of vestibular and peripheral visual field motion cues. Based on measured low-frequency operator behavior in three visual field environments, a parallel channel linear model is proposed which has separate visual and vestibular pathways summing in a complementary manner. A dual-input describing function analysis supports the complementary model; vestibular cues dominate sensation at higher frequencies. The describing function model is extended by the proposal of a non-linear cue conflict model, in which cue weighting depends on the level of agreement between visual and vestibular cues.

Spatial selectivity in visual search

Abstract: To what extent does successful search for a target letter in a visual display depend on the allocation of attention to the target’s spatial position? To investigate this question, we required subjects to discriminate the orientation of a briefly flashed U-shaped form while searching for a target letter. Performance operating characteristics (POCs) were derived by varying the relative amounts of attention subjects were to devote to each task. Extensive tradeoffs in performance were observed when the orientation form and target letter occurred in nonadjacent display positions. In contrast, the tradeoff was much more restricted when the two targets occurred in adjacent positions. These results suggest that the interference between simultaneous visual discriminations depends critically on their separation in visual space. Both visual search and form discrimination require a common limited-capacity visual resource.

The role of visual-auditory "compellingness" in the ventriloquism effect: implications for transitivity among the spatial senses

Abstract: A magnitude estimation response procedure was used to evaluate the strength of visualauditory intersensory bias effects under conditions of spatial discrepancy. Maj or variables were the cognitive compellingness of the stimulus situation and instructions as to the unity or duality of the perceptual event. With a highly compelling stimulus situation and single-event instructions, subjects showed a very high visual bias of audition, a significant auditory bias of vision, and a sum of bias effects that indicated that their perception was fully consonant with the assumption of a single perceptual event. This finding reopens the possibility that the spatial modalities function as a transitive system, an outcome that Pick, Warren, and Hay (1969) had expected but did not obtain. Furthermore, the results support the model for intersensory interaction proposed by Welch and Warren (1980) with respect to the susceptibility of intersensory bias effects to several independent variables. Finally, a new means of assessing intersensory bias effects by the use of spatial separation threshold was demonstrated.

Texture perception: studies of intersensory organization using a discrepancy paradigm, and visual versus tactual psychophysics.

Abstract: Three experiments were performed involving the perception of surface texture. Experiment 1 indicated that when vision and touch are presented with discrepant information concerning texture, the two senses appear to weight the information about equally. Moreover, Experiment 2 showed that using touch, vision, or touch and vision, subjects performed a texture identification task with comparable matching accuracy and precision. Experiment 3 demonstrated that using the same three modes, subjects performed a magnitude estimation task similarly, in terms of magnitude estimates of roughness, the rates of growth of perceived roughness, and response precision. The comparability of the two senses in texture-related tasks may underlie the relatively equal compromise between discrepant sources of texture information demonstrated in Experiment (modality superiority interpretation). Such a compromise is somewhat different from that commonly reported in the sensory conflict literature. The relative weighting of multiple sources of sensory information about surface texture was also considered in terms of a directed-attention interpretation of intersensory organization.

Early Visual Perception

Abstract: 1.0 INTRODUCTION 1.1 Toward a Perceptual Atom Theory .. 1.2 Personalia, Books, and Major Events .. 2.0 THRESHOLD PERCEPTION . 2.1 Spatial Frequency (SF) Channels .. 2.2 Spatiotemporal Channels . 3.0 SUPRATHRESHOLD PERCEPTION " ,', .,"""""""" .,"'"""' , .. 3,1 Contrast and Pattern Perception .. 3,1.} Bars versus Gratings and Shifts in Attention .. 3,1.2 Globality versus Low SF Channels .. 3,},3 The Problem of Phase . 3.2 Texture Discrimination: Beyond Autocorrelation . 3.3 Cross-Correlation Channels in Depth and Movement .

A taxonomy of visual processes

Abstract: Originally published in 1981, this third volume deals with the empirical data base and the theories concerning visual perception – the set of mental responses to photic stimulation of the eyes. As the book develops, the plan was to present a general taxonomy of visual processes and phenomena. It was hoped that such a general perspective would help to bring some order to the extensive, but largely unorganized, research literature dealing with our immediate perceptual responses to visual stimuli at the time. The specific goal of this work was to provide a classification system that integrates and systematizes the data base of perceptual psychology into a comprehensive intellectual scheme by means of an eclectic, multi-level metatheory invoking several different kinds of explanation.

Development of optokinetic nystagmus in infants: an indicator of cortical binocularity?

Abstract: The full-text of this book chapter is not available in ORA. Citation: Atkinson, J. & Braddick, O. J. (1981) Development of optokinetic nystagmus in infants: an indicator of cortical binocularity. In: Fisher, D. F., Monty, R. A. & Senders, J. W. (eds.) Eye movements: cognition and visual perception, Hillsdale, N.J: Lawrence Erlbaum, pp. 35-64.

Orienting Behavior by Rats with Visual Cortical and Subcortical Lesions

Abstract: The effect of visual cortical and subcortical lesions on orienting behavior was assessed bu examining the rats' ability to interrupt an ongoing response and perform appropriate head and postural adjustments to repeatedly presented auditory or apparently moving visual stimuli. Large lesions of the entire superior colliculus (SC) or the deep layers of the SC did not result in visual agnosia or the inability to perform the motor responses involved in orienting. Rather, the orienting response simply ws not emitted to visual stimuli that the intact rat treated as less salient, but was to those it treated as more salient. Lesions of either the superficial layers of the SC or visual cortex also did not completely prevent orienting to very salient, apparently moving visual stimuli, but did produce changes in the number of responses made to such stimuli and in the occurrence of other components of orienting behavior. It was suggested that the SC and visual cortex play a modulatory role in orienting behavior and that stimulus characteristics must be considered in the development of neuronal models of orienting behavior.

Visual and name coding in dyslexic children.

Abstract: Four experiments are reported which were designed to test for differences between dyslexic and non-dyslexic subjects at a number of visual information processing functions. It is argued that the older dyslexic child's reading problems cannot be ascribed to slowness of visual code production, to the limited capacity of the system, or to an extra rapid rate of decay. The results are compatible with the theory that, as a group, the dyslexic children tested show a slowness or inadequacy at a non-visual, name or linguistic coding level. It is suggested that this deficiency does not lie in the area of articulatory encoding but at an earlier stage where phonological or lexical codes are produced from visual stimuli.

Selective loss of binocular depth perception after ablation of cat visual cortex

Abstract: The massive visual projection to cortical areas 17 and 18 (striate and parastriate cortex) of the cat strongly suggests that these structures have a major role in visual processing. It is therefore paradoxical that ablation of these areas has been reported to result in very trivial deficits in their visual perception and behaviour1,2. In contrast to humans and monkeys, which show profound visual deficits after ablation of the visual cortex3–6, cats with similar lesions show essentially normal visual behaviour and are able to discriminate complex visual patterns. The only apparent effect of cortical lesions is a mild impairment of the visual acuity for gratings and a possibly greater reduction of vernier acuity7. In the past, the functional deficits resulting from lesions or ablations of various cortical structures have provided important clues to the function of many cortical areas, but recently a more detailed picture has emerged from electro-physiological studies of the properties of their constituent neurones. A striking aspect of most visual cortical cells in both cat and monkey is their specificity for horizontal retinal disparity8–10, the detection of which is a prerequisite for stereopsis11. This suggests that the visual cortex may play a major part in mediating stereopsis. We report here that ablation of cortical areas 17 and 18 in the cat results in severe selective deficits in binocular depth perception consistent with a loss of stereopsis.

About the Role of Visual Exploration in Aesthetics

Abstract: Descartes is probably the first known person to recognize the importance of eye movements in vision and visual perception, although Leonardo da Vinci may have recognized this before him.