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Results for “FORM PERCEPTION”

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PubMed1977

Subjective and objective symmetry in perception of form.

A new quantitative measure of the physical symmetry of 2-dimensional shapes is proposed which relates it to the proportion of translational and rotational (TR) overlap between a figure and its mirror image. Category ratings of the apparent vertical symmetry of distorted diamond figures correlate highly with this measure while it is also an important contributor in the prediction of the apparent symmetry and geometricity of random polygons.

Choice Behavior↗
PubMed1979

Dichhaptic perception of forms by normal adults.

Dichhaptic perception of nonsense forms was examined in familial righthanders. In Exp. 1, 15 males and 15 females performed similarly, obtaining a non-significant right-hand superiority with a 5-sec. memory interval between presentation of stimuli and their choice-recognition response. Individual differences in Block Design scaled scores but not State or Trait anxiety were related to hand performance for both sexes. One strategy on a questionnaire was related to performance of males. Exp. 2 was a replication with the memory interval removed. A significant right-hand superiority was obtained and different strategies were related to performance of males and females.

Adolescent↗
PubMed2004

The influence of motion-defined form on the perception of spatially-defined form.

It is well established that the visual system is sensitive to the global structure--or "form"--of objects defined exclusively by spatial or motion cues, but it remains unclear how form perception combines spatial and motion cues if these are presented concurrently. In the present study, we introduce a novel class of stimuli where spatial-form and motion-form can be superimposed and manipulated independently. In both the spatial and motion domains, global structure consisted of radial-frequency (RF) contours defined by a virtual circle of Gabor elements whose positions and/or drift speeds were sinusoidally modulated at a specified frequency of polar angle. The first two experiments revealed that observers encode the global structure of spatial-RF and motion-RF contours presented in isolation. In a third experiment, observers detected a spatial-RF modulation superimposed on a motion-RF pedestal of identical radial frequency: results showed little facilitation at low pedestal amplitudes but significant masking at higher pedestal amplitudes, especially if the RF modulations of test and pedestal were in anti-phase. Additional experiments demonstrated that masking of the spatial-RF test is abolished if the global structure of the motion-RF pedestal is altered or destroyed while local motion cues are preserved. We argue these results cannot be explained by local neural interactions between spatial and motion cues and propose instead that data reflect higher-level interactions between separate visual pathways encoding spatial-form and motion-form.

Cues↗
PubMed1992

Perceptual ambiguity and the short wavelength sensitive visual pathway.

Visual illusions and ambiguous figures are difficult to perceive when presented in a manner which stimulates only chromatic pathways. This perceptual limitation could indicate that these pathways are unable to mediate form perception, or it may reflect the relative visibility of the stimulus, regardless of the pathway utilized. To examine this issue, an ambiguous figure (illusory Necker cube) was presented to the short wavelength sensitive (S) cone pathway which is thought to convey only chromatic signals. Although few observers could recognize the cube when presented in isolation to S cones, the same reduction in recognition was found when the cube was detected by achromatic pathways at a level of visibility comparable to that conveyed by S cones. Our results indicate that for this object recognition task, visibility of the stimulus is the relevant variable, rather than the particular pathway traversed. Prior experience was also found to be important determinant of object recognition.

Color Perception↗
PubMed2000

Representation of stereoscopic edges in monkey visual cortex.

Form perception in random-dot stereograms is based on information that resides in the correlation between the two images, but is not present in either image alone. We have studied the coding of stereoscopic figures in the neural activity of areas V1 and V2 of alert behaving monkeys. While cells in V1 generally responded according to the disparity of the surface at the receptive field, we found cells in area V2 that responded selectively to the figure edges. These cells signaled the location and orientation of contrast borders as well as stereoscopic edges, and were often selective for the direction of the step in depth. We concluded that stereoscopic edges are explicitly represented in area V2.

Animals↗
PubMed2002

Comparison of color and luminance vision on a global shape discrimination task.

We compared the performances of the blue-yellow, red-green and luminance systems on a shape discrimination task. Stimuli were radial frequency patterns (radially modulated fourth derivative of a Gaussian) with a peak spatial frequency of 0.75 cpd. Stimuli isolated the chromatic (red-green and blue-yellow) and achromatic post-receptoral mechanisms. We showed that in all cases performance, measured as a radial modulation threshold for discrimination between a circular and non-circular stimulus, improves with contrast. Performance was compared across radial frequencies with contrast matched in multiples of stimulus detection threshold. We find that blue-yellow color system performs the worse on this shape discrimination task, followed by the red-green, with the achromatic system performing best. The average difference is a factor of 2 between achromatic and blue-yellow performance, and a factor of 1.7 between red-green and achromatic. Despite these performance losses, chromatic shape discrimination can still reach hyperacuity performance levels. In a secondary experiment we contrast modulate the radial contour to eliminate either the "corners" or "sides" of an RF4 (square) pattern. We find that for the achromatic system, the sides are more important for the task than the corners. However, for the chromatic system, removal of sides or corners produces similar performance deficits. We conclude that color vision has a selective although relatively mild deficit for two-dimensional form perception.

Color Perception↗
PubMed1999

Perception and neuronal coding of subjective contours in the owl.

Robust form perception and underlying neuronal mechanisms require generalized representation of object boundaries, independent of how they are defined. One visual ability essential for form perception is reconstruction of contours absent from the retinal image. Here we show that barn owls perceive subjective contours defined by grating gaps and phase-shifted abutting gratings. Moreover, single-neuron recordings from visual forebrain (visual Wulst) of awake, behaving birds revealed a high proportion of neurons signaling such subjective contours, independent of local stimulus attributes. These data suggest that the visual Wulst is important in contour-based form perception and exhibits a functional complexity analogous to mammalian extrastriate cortex.

Animals↗
PubMed1991

A Rorschach investigation of mothers of behaviorally disturbed infants.

This investigation focuses on one facet of the interactional family, parent-child, mother-infant matrix of behaviorally disturbed infants: the personality of mother as primary caregiver. Rorschach test behavior of mothers (N = 30) of behaviorally disturbed infants were compared with two normative samples. The Rorschach test was found to indicate certain atypical psychological patterns among these mothers. Differences emerged in intellectual sphere variables: number of responses (R), common detail responses (D), rare detail responses (Dd), number of accurate form percepts (F+), percentage of form percepts that are accurate (F+%), percentage of responses with animal content (A%), and popular percepts (P). Other response trends emerged in the affective sphere: percentage of pure form responses (F%) and in the interpersonal sphere: whole human content (H) and the ratio of the whole human content to human detail content (H:Hd), as well as to the test as a whole. Based on these results, hypotheses are generated for further investigation, particularly of traits in the areas of cognitive processing and the capacity for interpersonal relations.

Adolescent↗
PubMed2005

Causal relationship between health promoting behavior and quality of life in cervical cancer patients undergoing radiotherapy.

The purpose of this cross-sectional study was to examine the causal relationships among age, education, family income, and stage of carcinoma, perceived benefits, perceived barriers, perceived self-efficacy, health promoting behavior and quality of life in patients with cervical cancer. Pender's Health Promotion Model (1996) provided a guide for the conceptual framework of this study. Purposive sampling was employed to recruit 488 cervical cancer patients who were undergoing radiotherapy at seven public hospitals in five areas of Thailand. The instruments used in this study included a Personal Data Form, Cognitive perception Form, Health promoting behavior scale, the social support questionnaire and The Functional Assessment of Cancer Therapy General (FACT-G) form. The proposed model was tested and modified by the LISREL Program. The modified model adequately fitted with the data. The results demonstrate that health promoting behavior had a significant direct positive effect on quality of life (beta = 0.71, p < 0.01). Cognitive perceptual factors had a significant direct effect on health promoting behaviors (P = 0.69, p < 0.01). Social support had a significant direct effect on the cognitive perceptual factors (P = 0.64, p < 0.01), health promoting behavior (beta = 0.70, p < 0.01), and the quality of life (beta = 0.48, p < 0.01). Age and education did not have a significant total effect on the quality of life. Family income had a significant direct effect on cognitive perceptual factors (beta = 0.10, p < 0.05). The stage of cancer had a significant direct negative effect on cognitive perceptual factors (beta = -0.11, p < 0.05) and the quality of life (beta = -0.12, p < 0.01). The direct effect of the predictors on the quality of life indicated that cervical cancer patients with higher practice of health promoting behavior tended to have a higher quality of life. The findings indicate that Pender's Health Promotion Model is a useful guide for explaining and predicting the health promoting behavior and the quality of life of Thai cervical cancer patients who were undergoing radiotherapy. The significance of cognitive perceptual factors and social support confirm health promoting behavior as a goal directed towards the level of well being. This has implications for health care systems in planning interventions to promote health promoting behavior in a health promotion setting in cervical cancer patients for a better quality of life and healthy. A longitudinal study and experimental study are recommended for further study.

Adult↗