Figure Discrimination Research Articles

Temporal integration in the visual system: Influence of temporal dispersion on figure-ground discrimination

Psychophysical measurements were carried out with a microcomputer-controlled matrix of 32 × 32 light emitting diodes to determine temporal parameters of figure-ground separation processes. The task was to detect a figure that was dispersed in time. Between each two figure elements n noise elements were interspersed. The results of these experiments indicate that the discrimination of figures hidden in dynamic noise is possible even if figure elements are dispersed in time over several hundred milliseconds. The maximal dispersion time still compatible with figure discrimination ( T max ) depends critically on the number n of interspersed noise elements, on the subject's expectancy and on the number of elements used for the generation of the figure. For simple figures such as triangles T max could be as long as 1.5 sec when n was 4. Our experimental results suggest that the neuronal representation of the briefly displayed (<6 msec) pattern elements outlasts their physical presence by at least 400 msec. This persistence of neuronal representations must occur at a level of processing where retinotopy is still preserved, since the only cue for figure-ground discrimination is the difference in the local density of figure and noise elements.

Proprioceptive contributions to tactile identification of figures: Dependence on figure size

Studies on the recognition of objects or shapes explored by a hand or finger have concentrated on the relative merits of different methods of exploration — in particular, whether the exploring hand or finger is moved by the subject himself ( active), is guided by an assistant ( passive), or remains stationary with the shape being moved by an assistant ( tactile). These factors, together with another variable — the size of the explored shape — were investigated in twelve normal adults whose task, without the aid of vision, was to explore and identify various shapes with the tip of the extended right index finger. Two series of shapes were used, a large (15 cm) and small (3 cm) series, both of which consisted of twelve shapes each being a variant of the letter ‘S’. The shapes were outlined as rows of Braille-like dots on a flat surface. Exploration was also tested in the proprioceptive mode, in which the exploring hand was guided by an assistant around a shape which was simply drawn on the surface so as to give a minimum of tactile information. For neither large nor small shapes could we demonstrate differences between active, passive and proprioceptive exploration. For the small shapes, the active, passive and proprioceptive modes gave no advantage over purely tactile assessment. However, for the larger shapes, active, passive and proprioceptive modes allowed better identification than movement of the shape. Thus, purely cutaneous signals appear sufficient for optimal discrimination of small figures but proprioceptive signals, generated by movement, are needed for optimal discrimination of larger figures.

Spatial contrast sensitivity does not explain random figure discrimination latency.

Both humans and other mammals can more easily discriminate eight-sided figures from one another than they can figures having more or fewer sides. The hypothesis that this effect is based upon spatial contrast sensitivity was tested by varying viewing distance and hence spatial frequency content. Because viewing distance had tittle effect upon relative discrimination latency, it was concluded that the superior discriminability of eight-sided figures is not based upon spatial contrast sensitivity. The possibility that orientation tuning of visual cortex neurons may account for the effect is discussed.

Lesions of visual cortex impair discrimination of hidden figures by cats

Cats lacking cortical visual areas 17, 18 and 19 can discriminate between patterns equal in luminous flux. The present experiment investigated the extent to which this ability varies with differences in the amount of contour and complexity of the patterns. To test this, cats were required to discriminate between patterns that were made progressively more alike in contour and complexity by increasing the number of masking stripes superimposed on each of a pair of stimuli. A mild deficit in shape discrimination among cats with lesions of areas 17, 18 and 19 was greatly exacerbated by masking the stimuli with superimposed stripes, and the severity of the deficit for each operated cat was correlated with the size of the contour and complexity difference between the stimuli. Finally, the severity of the deficit was related to the amount of geniculocortical damage. The results suggest that lesions largely confined to areas 17, 18 and 19 cause profound deficits on masked pattern discrimination even though performance with unmasked stimuli is relatively unimpaired. Indirect evidence suggests that this effect is not due solely to a reduction in visual acuity.

Subtotal lesions of the visual cortex impair discrimination of hidden figures by cats.

Cats with partial or nearly total ablation of areas 17, 18, and 19 were assessed on the discrimination of hidden figures and other visually guided behaviors to determine whether such insults produce deficits like those that follow lateral striate lesions in monkeys. Cats with destruction limited to the representation of central vision (Group M) were impaired at discriminating patterns complicated by extraneous cues, but they were less impaired than cats with more complete lesions (Group MS). The deficit was not a general one in visual learning since animals in both Groups M and MS learned simple pattern discriminations as rapidly as controls. It is suggested that the loss of geniculocortical functions representing central vision produces similar deficits in cats and monkeys but that to have this effect in cats, damage must extend beyond area 17.

More about a thinning algorithm

The characteristics of the parallel operations exploited by a thinning algorithm presented by the authors in the past are considered. A new arrangement both of the masks implementing such operations and of their order of application is shown, which originates transformed figures having a number of branches greater than before. The present algorithm seems to be more helpful than standard thinning algorithms, when problems of figure discrimination are to be faced.

Young infants' visual processing of internal and adjacent shapes

Three experiments explored possible mechanisms mediating 1-month-old infants' differential discrimination of internal and external elements of compound visual patterns. Discrimination was inferred from recovery of operant sucking to the presentation of a novel pattern following decrement to a familar pattern. In Experiment 1, infants were familarized with a small geometric figure either centered within, or placed adjacent to, a larger figure. There was no evidence for discrimination of shape changes in small figures presented in either pattern. However, Experiment II showed discrimination of shape changes in small figures presented singly. Experiment III investigated discrimination of shape changes in small figures placed adjacent to either another small figure or a larger figure. Averaged data indicated no reliable discrimination in either group. But there was evidence for a group difference in the distribution of subjects' recovery scores, suggesting better discrimination of small figures when placed adjacent to another small figure. The pattern of results is interpreted in terms of an early attentional bias toward the larger components of compound patterns.

Visual recognition and discrimination of random figures with black and white square cells

The purpose of this study is to clarify quantitatively the relation of the physical nature of figures to the recognition and discrimination characteristics of vision when an observer views and perceives the form of two-dimensional figures. Thus, visual experiments are made by means of standard and test random figures composed of 12×12 square cells, some of which are painted black as picture elements. These figures are recognized and discriminated by several student observers with visual acuity not less than 0.8. Results obtained are as follows:(1) Display time duration of 4 to 5 seconds is adequate for observers to recognize or discriminate the stimulus figures.(2) Averaged number of additional or subtractive picture elements of test figures required to obtain a constant discrimination rate is proportional to the predetermined number of picture elements of the standard figure; i.e., the Weber ratio is constant.(3) Test figures with picture elements of different spatial distributions are discriminated with different discrimination rates, even though the numbers of these elements are the same; i.e., the perceived psychological quantities of picture elements vary with their spatial positions.

Infants' discrimination of internal and external pattern elements

Human infants' discrimination of changes in internal and external elements of compound visual patterns was investigated in four experiments employing a familiarization-novelty paradigm in which visual reinforcing patterns were presented contingent upon rate of high-amplitude nonnutritive sucking. In Experiment 1, 4-month infants discriminated changes in the shape of internal, external and both internal and external figures. One-month infants discriminated external changes in both internal and external figures, but failed to show reliable response recovery when only internal figures were changed. Experiments 2 and 3 failed to explain the 1-month results on the basis of poor resolution of internal figures by showing comparable discrimination of small and large singly-presented figures and by failing to find improved internal discrimination with large separation between internal and external figures. In Experiment 4, 1-month infants showed response recovery to figure additions made adjacent to the initial figure, but not to internal additions. The results are interpreted in terms of attentiveness by young infants to external pattern elements and may indicate early processing of figure-ground information. The developmental differences observed suggest an increased breadth of attention to pattern elements.

Visual discrimination of flux-equated figures by cats with brain lesions

Cats with various brain lesions were compared in their abilities to learn or relearn for food reward to a strict performance criterion a simple dark-light discrimination and 3 sets of discriminations between pairs of triangles equated for overall luminous flux. The results revealed a spectrum of deficits in visual learning by cats with different lesions and indicate: (1) cats with bilateral lesions of the superior colliculus-pretectum can learn dark-light and geometric figure discriminations in approximately the same number of training trials as unoperated cats or as cats with bilateral lesions of the lateral-posterolateral and splenial gyri; (2) cats with bilateral lesions of the superior colliculus-pretectum can learn to discriminate from a distance between geometric figures equated for overall luminous flux; (3) cats with bilateral lesions of the suprasylvian and ectosylvian gyri in addition to the lateral-posterolateral and splenial gyri require more training to learn both types of visual discriminations than unoperated cats or cats with lesions either of the superior colliculus-pretectum or of the lateral-posterolateral and splenial gyri; (4) cats require either an intact superior colliculus-pretectum or intact lateral-posterolateral and splenial gyri in order to discriminate between geometric figures; (5) cats with bilateral lesions of the posterior two-thirds-three-fourths of the neocortex and most of the superior colliculus-pretectum can learn a simple dark-light discrimination after prolonged training.

Factors influencing the acquisition of tactual random figure discriminations by rhesus monkeys

Rhesus monkeys learned to perform two-object random figure discrimination problems by touch. This performance was compared to the visual acquisition of the same problems (reported earlier). In both modalities, choice latencies were shorter to the correct than to the incorrect figure. As compared to visual, however, tactual learning required significantly more trials to criterion, was independent of stimulus figure complexity, and was characterized by significantly shorter choice latencies. Rotation of the figures 180 deg after criterion performance was achieved, yielded partial recognition of the figures visually, but no recognition tactually. These results are explained by different observational or cue-utilization strategies. The majority of the figure is inspected visually, but only the same small section of the perimeter is used tactually. Thus, restricted use of the available cues characterizes tactual performance and is responsible for generating differences in various measures of learning between vision and touch in the monkey.

Copying in Drawing: The Importance of Adequate Visual Analysis versus the Ability to Utilize Drawing Rules

RAND, COLLEEN WRIGHT. Copying in Drawing: The Importance of Adequate Visual Analysis versus the Ability to Utilize Drawing Rules. CHILD DEVELOPMENT, 1973, 44, 47-53. Copying in drawing requires many skills. 2 theoretically important abilities are visual analysis and drawingrule utilization. In this experiment, training methods designed to improve preschool children's ability to analyze figures and to utilize drawing rules were compared in terms of their effects on figure discrimination and copying accuracy. Drawing-rule utilization resulted in improved copying accuracy but did not improve discrimination ability, while training in visual analysis resulted in improved discrimination ability but not improved copies. Further, increased improvement in figure discrimination was related to decreased copying accuracy. It was concluded that drawing rules are essential and that adequate visual analysis is a necessary but not sufficient prerequisite to the production of accurate copies.

Extrageniculostriate vision in the monkey: Discrimination of luminous flux-equated figures

Six monkeys (Macaca mulatta) were tested before and after histologically confirmed total removal of the striate area and complete degeneration of the lateral geniculate nuclei. Using Klüver's pulling-in technique with nonmovable transillu-minated targets, two discrimination problems were given at both a high and a low photometric level. In the first test, the targets were of equal area and differed in luminance and total luminous flux (B-F problem). In the second test, figures differed in luminance and area in an inverse proportion (BA problem) which resulted in their being closely matched for total luminous flux. Postoperatively, the animals showed significant deficits on all tests. Every monkey, however, achieved criterion level of performance not only on the B-F but on the BA problem as well. Performance on the latter test did not change after dilatation of the pupils, or when minimal flux differences were eliminated as cues by making the rewarded target to have the lesser flux in half of the trials and the greater flux in the other half. These findings indicate that monkeys can be trained to discriminate between stimuli equated for total luminous flux after exclusion of the geniculostriate system. Although it is possible that other stimulus parameters are discriminated by such animals, our results do not necessarily negate Klüver's original concept. Indeed, destriated monkeys may still utilize a luminous flux cue to discriminate flux-equated figures through the detection of differences in the rate of change of this parameter during eyes, head and/or body movements.

Simultaneous visual discrimination in rats: training strategies.

Stimulus pretraining methods were found to be ineffective in facilitating the learning of simultaneous figure discrimination in rats. A difficult brightness discrimination was learned but stimulus pretraining had no effect on learning. The absence of a visual stimulus, although correlated with reward, was not sufficient to produce approach responses to a darkened key, in one pretraining condition. The failure to learn the figure discrimination may be attributed to emotional factors and to a lack of correlated cues rather than to inattention or to an inadequacy in the rat's visual apparatus.

A developmental study of tactual discrimination in blind and sighted children and adults

Normally sighted, partially sighted and totally blind Ss from 6 years to adults performed a tactual discrimination task requiring them to judge whether two raised line figures were alike or different. The number of errors made in the task depended on the age of S, the amount of vision present, and the nature of the differences between members of the pairs. These results were compared to data obtained by other investigators on visual discrimination of similar figures.

Improved visual recognition during hypnosis.

AMBIGUITY IS an important factor in many perceptual phenomena and a vital experimental determinant. As Kris has demonstrated,¹it plays a role in the aesthetic experience. Tarachow²recently described its role as the basis of much of our humor, in which the incongruities of the situation are often stimulated by the multiple meanings of the stimulus. The classical perceptual studies of Rubin,³with the exploration of figure and ground and the fascinating phenomenon of reversible figures have proved a fruitful source of experimental techniques. The "double profile" was employed in Schafer and Murphy's early study⁴of idiosyncratic perception of an ambiguous figure, one of the first attempts to illustrate the effect of individual motivation in perception. The discrimination of figure and ground also proved basic in Witkin's studies of characterological perceptual styles,⁵while the Rubin double profiles were one of the earliest stimuli used

Shape discrimination in the octopus.

IN a recent communication1, P. C. Dodwell raises some doubts about the adequacy of a theory of visual shape discrimination in octopus which I outlined in Nature 2. Dodwell makes four points: (1) He thinks it would be difficult to devise an analysing mechanism which would analyse relative differences in rates of firing at different points over a row of neurons: such a mechanism is necessary on my theory to explain the discrimination of certain figures (for example, a square and a circle). (2) He maintains that the theory fails to account for discrimination of shape irrespective of the locus of excitation on the retina. (3) He writes: “the reason for postulating the array of cells [in the optic lobes] becomes obscure, because … the analyser … should enable it to deal directly with information from the retina”. (4) He maintains that a theory of shape discrimination which he is putting forward overcomes the difficulties inherent in my own theory by transforming a spatial pattern into a temporal pattern.

The Effects of Colored Surroundings on Mental Performance and Psychogalvanic Reflex

Color lights used for the research introduced in this article were selected from the chromatic table. The visual field was filled with a single color.Ninety university students who volunteered for the test were asked to perform mental work (Visual discrimination of figures (Landolt's circles of 2 minute) or mental arithmetic) in ten minutes in different colored surroundings (i. e. white, red, yellow, green and blue surrounding-s). Results obtained are as follows:The effects of colored surroundings upon the mental performance was clearly recognizable.(1) Performance of the students in green or blue surroundings falls behind that in white, red, and yellow surroundings, when compared in the terms of the volume of work completed(2) The subjects discriminated figures with more ease in white surroundings than in the surroundings in other colors.Many subjects had difficulty in blue surrounding in performing mental arithmetic.(3) Psychogalvanic reflex during mental work was the largest when measured in the red surrounding and smallest in the blue surrounding.Amplitude of psychogalvanic reflex measured of the subject as he entered in the colored room was fairly large but it was reduced as he was adapted to the given surrounding.We found the curves of psychogalvanic reflex become flat as the subject was concentrated in mental work.

Visual figure discrimination and the mediation of equivalence responses.

Visual figure discrimination and the mediation of equivalence responses.

Studies in concept formation. IV. A comparison of white rats and raccoons with respect to their visual discrimination of certain geometrical figures.

Studies in concept formation. IV. A comparison of white rats and raccoons with respect to their visual discrimination of certain geometrical figures.