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PubMed1987

Finding parts within figures: a developmental study.

Preschool children, primary school children, and unschooled adults were tested on the part-probe task designed by Palmer. Relatively high scores were obtained with all groups on parts which had a 'good' relationship with the figure. However, the ability to find more deeply embedded segments was not present in the preschool children or in the unschooled adults. This indicates that the processes of postperceptual analysis necessary to find a part in a figure are neither built-in nor the consequence of mere cognitive growth, but depend on the instruction or experience usually provided in school. Such processes should not be confused with those that lead to form perception. Inspection of the part-figure pairs and of the corresponding detection scores suggests the importance of several stimulus properties.

Adult↗
PubMed1976

Irrelevance of figural identity for resolving ambiguities in apparent motion.

In order to examine the degree to which form perception affects the formation of apparent-motion experience, subjects were presented with nine ambiguous apparent-motion situations, where the elements of each single flash were various figures. One of the interpretations of each situation preserved the figural identity of the figures across flashes. It was found that figural identity does not have any effect on determining the type of motion experienced, except when the figural analysis involved is relatively simple.

Form Perception↗
PubMed1985

Measurement and prediction of diagnostic performance during radiology training.

Faculty evaluations of residents' diagnostic performance in radiology subspecialty rotations were examined in two studies in order to ascertain whether the relative capabilities of residents change during training and to predict residents' diagnostic performance using a three-dimensional form perception test. In the first study, numeric ratings by faculty members were averaged to provide interpretive/diagnostic scores for each of 16 residents in each of 5 consecutive half-years. Sixty-seven percent of the relative differences among residents' diagnostic proficiencies persisted during training. The magnitude of these unchanging differences between individuals in diagnostic performance strongly favors resident selection based upon diagnostic potential. An additional 22% of the relative differences correlated with an abrupt change in the rank order of residents in diagnostic performance at the beginning of the second year of residency. This rearrangement of ranks may have resulted from an abrupt change in the tasks and expectations assigned to residents. In the second study, correlations between scores on a recently described Form Test and monthly faculty ratings of diagnostic performance were computed. An average diagnostic performance score for each resident was generated for all rotations combined, each of eleven subspecialties, and all rotations completed within a given half-year. Scores on the Form Test correlated well with these combined diagnostic scores, further substantiating results reported previously. Form Test scores were highly correlated with subspecialty diagnostic performance scores in subspecialties using cross-sectional imaging methods, such as neuroradiology. Although Form Test scores were poorly correlated with half-year diagnostic performance during the first year, they were highly correlated with performance beginning in the second year.

Educational Measurement↗
PubMed1990

Sensory integrative processing in delinquent-prone and non-delinquent-prone adolescents.

The purposes of this study were to obtain a preliminary description of the sensory integrative and practic abilities of 114 non-delinquent-prone adolescents aged 12 through 18 years and to compare their performances with those of 12 delinquent-prone adolescents with learning problems. Ten of the 17 subtests of the Sensory Integration and Praxis Tests (SIPT) (Ayres, 1989) as well as the Finger Posture Imitation Test (Druker, 1980) and the MacQuarrie Test for Mechanical Ability (MacQuarrie, 1925/1953) were administered to both groups. It was hypothesized that performance on some tests would correlate with age in the non-delinquent-prone adolescents. It was also hypothesized that some delinquent-prone adolescents with learning problems would perform significantly worse on the tests of sensory integrative and practic abilities than would the non-delinquent-prone adolescents. A data analysis indicated that performance on the praxis tests, Manual Form Perception, Graphesthesia, and Bilateral Motor Coordination showed a significant age correlation. The results of this study indicated a difference between the two groups, and it was concluded that the delinquent-prone group performed more poorly on all of the praxis-related tests and on the absolute values of the tests of Postrotary Nystagmus, Standing and Walking Balance, and Bilateral Motor Coordination. Some of the vestibular- and praxis-related tests, therefore, may still provide useful information on children older than 8 years of age.

Adolescent↗
PubMed1991

Image enhancement for the visually impaired. Simulations and experimental results.

Digital image enhancement has been proposed as an aid for the visually impaired. The capability of two enhancement techniques to improve recognition of images by patients with central scotoma or cataracts was evaluated using image-processing simulations and direct patient testing. Enhancements and simulations were based on measurements of contrast sensitivity loss for patients with macular disease. Contrast sensitivity loss was measured using Gabor-type localized stimuli and paradigms that are appropriate for analyzing form perception. The simulations using the contrast sensitivity data suggested that patients with moderate visual loss (20/70-20/200) may have difficulty recognizing faces and may benefit from enhancement by both of the techniques used. Ability to recognize celebrities from enhanced images improved for 39 of the 46 patients tested. The improvement was significant (P less than 0.05) for 16 of the 38 patients with central visual loss and for 3 of 8 patients with anterior segment media opacities tested. The simulations suggest that the benefits of image enhancement may be similar or even greater for recognition of other types of images.

Adult↗
PubMed1996

A neurological dissociation between shape from shading and shape from edges.

We studied the ability of a neurological patient, who has deficits in various aspects of form perception, to perform region segregation tasks requiring discriminations based on several image properties that are related to the three-dimensional structure of objects. The patient could discriminate the apparent three-dimensional structure and orientation of shapes defined by shading gradients, but could not make such discriminations for shapes in which edges were depicted as lines or as luminance discontinuities. These results suggest that the neural pathways that compute shape from shading gradients may be independent of those that compute shape based on edges, and, based on the patient's pattern of brain damage, they also indicate a relatively early functional separation in the requisite inputs.

Adult↗
PubMed1981

Perceptual processing strategies in the cross-modal transfer of form discrimination: a developmental study.

Groups of Grad 1, high school students, and elderly subjects were tested for their ability to discriminate tactile forms. The performance of control subjects who received no prior training was compared with that of subjects who received prior visual training under normal viewing conditions (Vw), or prior visual training with special goggles restricting form perception to a series of part impressions (Vp). Both the visual and tactile versions of the task involved comparisons of standard figures matched either with themselves or with transformation figures. There was no evidence of transfer for the children, regardless of previous experience. Specific as well as nonspecific cross-modal transfer was found in the high school and elderly groups following Vp training. Positive transfer was also found for the high school students in the Vw condition, although there is some question whether this was the result solely of cross-modal effects. Whereas all age groups performed equally well on standard versus transformation comparisons, standard versus standard matches were highest in the high school students, lowest in the children, and intermediate in the elderly. The generally poor performance of the children and the inability on the part of the elderly to benefit from Vw training are discussed in terms of task difficulty and inefficient perceptual processing strategies.

Adolescent↗
PubMed1992

Neural mechanisms of tactual form and texture perception.

In the last decade or so, there has been rapid movement toward the use of more complex stimuli in the study of perceptual function related to the hand. This review has focused on the neural mechanisms of form and texture perception. Evidence from neurophysiological and psychophysical studies in which static touch, scanning touch, and the Optacon were used indicate that the spatial acuity of the RA system may be as much as three times poorer than the SAI system, evidence that suggests that form perception is dominated by the SAI system. Pattern recognition behavior in a tactual letter recognition task appears to be directly related to the response properties of SAI afferent fibers. Psychophysical studies of roughness perception show that roughness magnitude is related to surface structure in an orderly manner. Because roughness varies along an intensive continuum, mean impulse rate in one or more of the afferent systems is the most obvious coding possibility. No satisfactory relationship between mean impulse rate and roughness has been observed, however. The strongest hypothesis is that tactual roughness perception is based on spatial variation in the SAI population response. The combined evidence from studies reviewed here suggests complementary roles for each of the afferent systems, which are presented as working hypotheses: The SAI system is the primary spatial system and is responsible for tactual form and roughness perception when the fingers contact a surface directly and for the perception of external events through the distribution of forces across the skin surface. The PC system is responsible for the perception of external events that are manifested through transmitted high-frequency vibrations of the kind that are critical in the use of objects as tools. The RA system is responsible for the detection and representation of localized movement between skin and a surface as well as for surface form and texture when surface variation is too small to activate the SAI afferents effectively.

Animals↗
PubMed1995

Level of processing in the perception of symmetrical forms viewed from different angles.

This study is concerned with the level of processing underlying the perception of symmetry about a vertical axis. Specifically, it asks whether the equality of the two sides of a symmetrical pattern must be present retinally or perceptually for the impression of symmetry to be realized. Sixty-four subjects were assigned to groups that viewed symmetrical and asymmetrical figures when the figures were in either a frontoparallel plane or one slanted by 65 deg from the line of sight. In the 65 deg condition, the objectively symmetrical stimuli projected an asymmetrical shape on the retina, and conversely the objectively asymmetrical stimuli produced a symmetrical retinal projection. From each viewing angle, patterns were observed under either full or reduced (monocular) depth cue conditions. Like their counterparts in the frontoparallel condition, observers in the 65 deg, full depth-cue condition identified the objective symmetry of the figures. By contrast, 65 deg, reduced depth-cue observers responded primarily to the retinal structure of the stimuli. The same pattern of responding was observed for both holistic and multielement patterns and for both 100 ms and 1 s exposures. These findings and the significant relationship obtained between phenomenal judgment of symmetry and a measure of shape constancy suggest that the perception of symmetrical figures depends upon the perception of the equality of their two halves, and is thus another example of perceptual causality.

Adolescent↗
PubMedDate not supplied

Developmental assessment: 18 months to 4 1/2 years. The Bus Puzzle Test.

The Bus Puzzle Test for assessing developing language and some performance skills has been standardized on a sample of 425 children living in an inner city area and a rural market town. The age range was 18 months to 4 1/2 years. The study provides levels of achievement in comprehension by age and shows the importance of the 27-33 months period in the development of situational understanding. Assessment of expressive language takes account of the strategies employed by young children to express meaning. The early stages of form perception are examined. Results are provided in graphic and tabular forms and provide a data base for converting an individual child's scores into variation from average.

Child Development↗
PubMed1975

[Functional hemispheric asymmetry in perception of random forms (author's transl)].

2 experiments were conducted in which Ss made the "same-different" judgement with respect to a pair of random forms which were serially presented to the right and the left VF tachistoscopically. In Exp. I, the stimulus materials were random form painted solidly, and in Exp. II they were contour forms. The major results of both experiments were essentially the same. The results indicated that right VF-lead condition produced more errors than the left VF-lead condition, and that the high complexity form group produced more errors than the low complexity form group. The tendency of left VF-lead superiority was more pronounced when the interval between the 2 stimuli was longer. These results suggest the possibility of the right hemisphere's superior function concerning the perception of random forms.

Adult↗
PubMed1994

Spatial reference systems in the comprehension of rotational motion.

In certain simple rotations of objects, the orientation of the axis and planes of rotation can determine whether people are able to visualize the motion or perceive it as simple and coherent. This finding affords the opportunity to investigate the spatial reference systems used to define the orientation of the axis and planes of rotation. The results of two experiments suggest that the permanent environment is the primary reference system, apart from the rotating object, used for this purpose. Subjects also were able to use a local spatial environment to determine the orientation of the motion; some subjects were particularly adept at this. The viewer perspective, in contrast, was irrelevant as a reference system in these experiments. These results argue strongly for the primacy of environmental reference systems in the perception and imagination of orientation and extend the set of findings common between the comprehension of rotational motion and orientation-sensitive form perception.

Environment↗