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At least 343 records · Page 19Linked to original sources
PubMed1999

Visual perception: here's mud in your mind's eye.

We appear to be unaware of large changes in our visual scene if our attention is temporarily diverted. This suggests that the rich, complete visual scene that we appear to have may be just an illusion.

Animals↗
PubMed1986

Testing visual perception of three-dimensionally moving objects (dynamic stereoscopy).

In the past decade, visual requirements in the field of stereoscopy have considerably increased in a number of professions, as well in present-day traffic and sports. As a result of a statement of the WHO (1984) viz. that for prevention of accidents the testing of static vision only is insufficient, and that dynamic vision too should be a subject of investigation, a test for measuring dynamic stereoscopic visual acuity has been devised. With the help of two synchronously rotating prisms, a stereo test consisting of four bars is transposed into an apparent circumduction movement which is presented at different velocities. Stereoscopy under static and dynamic conditions do not run a parallel course. Dynamic stereoscopy is significantly influenced by age, but not by sex.

Adult↗
PubMed2001

Audio-visual perception of sinewave speech in an adult cochlear implant user: a case study.

OBJECTIVE: The purpose of this case study was to investigate multimodal perceptual coherence in speech perception in an exceptionally good postlingually deafened cochlear implant user. His ability to perceive sinewave replicas of spoken sentences, and the extent to which he integrated sensory information from multimodal sources was compared with a group of adult normal-hearing listeners to determine the contribution of natural auditory quality in the use of electrocochlear stimulation. DESIGN: The patient, "Mr. S," transcribed sinewave sentences of natural speech under audio-only (AO), visual-only (VO), and audio-visual (A+V) conditions. His performance was compared with the data collected from 25 normal-hearing adults. RESULTS: Although normal-hearing participants performed better than Mr. S for AO sentences (65% versus 53% syllables correct), Mr. S was superior for VO sentences (43% versus 18%). For A+V sentences, Mr. S's performance was comparable with the normal-hearing group (90% versus 86%). An estimate of the amount of visual enhancement, R, obtained from seeing the talker's face showed that Mr. S derived a larger gain from the additional visual information than the normal-hearing controls (78% versus 59%). CONCLUSIONS: The findings from this case study of an exceptionally good cochlear implant user suggest that he is perceiving the sinewave sentences on the basis of coherent variation from multimodal sensory inputs, and not on the basis of lipreading ability alone. Electrocochlear stimulation is evidently useful in multimodal contexts because it preserves dynamic speech-like variation, despite the absence of speech-like auditory qualities.

Adult↗
PubMed2000

The relevance of visual perception to cortical evolution and development.

The quality of brightness--perhaps the simplest visual attribute we perceive--appears to be determined probabilistically. In this empirical conception of the perception of light, the stimulus-induced activity of visual cortical neurons does not encode the retinal image or the properties of the stimulus per se, but associations (percepts) determined by the relative probabilities of the possible sources of the stimulus. If this theory is correct, the rationale for the prolonged postnatal construction of visual circuitry--and the evolution of this visual scheme--is to strengthen and/or create by activity-dependent feedback the empirically determined association on which vision depends.

Animals↗