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At least 919 records · Page 51Linked to original sources
PubMed2006

Distinct mechanisms of form-from-motion perception in human extrastriate cortex.

The exquisite sensitivity of the human visual system to form-from-motion (FfM) cues is well documented. However, identifying the neural correlates of this sensitivity has proven difficult, particularly determining the respective contributions of different motion areas in extrastriate visual cortex. Here we measured visual FfM perception and more elementary visual motion (VM) perception in a group of 32 patients suffering from acute posterior brain damage, and performed MRI-based lesion analysis. Our results suggest that severe FfM perception deficits without an associated deficit of VM perception are due to damage to ventral occipito-temporal cortex (VOT), whereas associated deficits of FfM and VM perception are due to damage either in proximity to area MT+/V5 or an area including lateral occipital complex (LOC) and VOT. These data suggest the existence of at least three functionally and anatomically distinct regions in human visual cortex that process FfM signals.

Adult↗
PubMed2004

Patient's perception of location, form and size in case of cavity preparation.

The aim of the present study was to clarify the difference between the imagination of patients and the reality in regard to the location, the form and the size of the cavity in case of cavity preparation for dental restoration. Firstly, we manufactured the dummy dentition for simulated cavity preparation and the operator intra-orally prepared a cavity on the dummy dentition in subject to confirm its validity. Then, 5 operators intra-orally prepared prescribed cavities at the both sides of maxillary first molars on the dummy dentition in every one of 5 subjects with masking. We compared the location, the form and the area of these prepared cavities with those imagined by subjects, respectively. In 58% of cases, the subjects could accurately recognize the location of prepared teeth. And 34% of cases also determined the Class of cavity form. The imagined area was larger than the actual area and the difference was statistically significant (p < 0.001). These results suggested that the perception of the patients regarding the location and the form of the prepared cavity was inaccurate during cavity preparation and patients tended to overestimate amounts of removed tooth substance.

Adult↗
PubMed1992

Integration of sequential information for shape perception by infants: a developmental study.

Perception of form by spatiotemporal integration was investigated in 3 experiments. In the first, infants aged 8, 10, and 12 months were tested using a novelty-preference procedure to determine the earliest age at which recognition of rectilinear and curvilinear form occurred. Infants were shown a light-point tracing of the outline of a figure, followed by simultaneous presentation of 2 test objects, one of the same shape as the tracing and one of a different shape. The tracing was double the size of the test objects. Only infants in the oldest group responded selectively by looking longer at the object of different shape. In the second experiment with 12-month-old infants only, it was shown that recognition of rectilinear, but not curvilinear, form occurred despite a difference in the orientation and size of tracing and object. Computer-generated tracings were used in the final experiment to compare form recognition for 2D and 3D stimuli. Selective responding occurred only for the latter. These findings show that by 12 months infants perceive the correspondence between the figural properties of a tracing and its extended form, but that this perception is dependent on the provision of depth cues.

Cognition↗
PubMed2003

Attention enhances feature integration.

Perceptual processing delays between attribute dimensions (e.g. color, form and motion) [Proceedings of the Royal Society of London Series B 264 (1997) 1407] have been attributed to temporal processing asynchronies resulting from functional segregation of visual information [Science 240 (1988) 740]. In addition, several lines of evidence converge to suggest that attention plays an important role in the integration of functionally processed information. However, exactly how attention modulates the temporal integration of information remains unclear. Here, we examined how attention modulates the integration of color and form into a unitary perception. Results suggest that attending to the location of an object enhances the integration of its defining attributes by speeding up the perceptual processing of each attribute dimension. Moreover, the perceptual asynchrony between attributes remains constant across attended and unattended conditions because attention seems to offer each processing dimension an equal processing advantage.

Attention↗