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At least 181 records · Page 10Linked to original sources
PubMed1990

The Charles Bonnet syndrome. Visual perceptive dysfunction in sensory deprivation.

We present a series of four patients with the Charles Bonnet syndrome, which is characterized by recurrent vivid visual hallucinations in the presence of normal cognition and insight. It usually occurs in elderly people with ophthalmic pathology causing severe visual sensory deprivation. Our experience suggests that this syndrome is frequently overlooked or misdiagnosed by both ophthalmologists and psychiatrists. To our knowledge this is only the second series of cases of the syndrome in the American literature.

Adult↗
PubMed1978

Comparison of the visual perception of a runway model in pilots and nonpilots during simulated night landing approaches.

Relative motion parallax, a cue that can contribute to visual judgments of glide path angle, was studied for its effect on simulated nighttime approaches in two experiments: 1) 16 pilots and 16 nonpilots adjusted the slant of a model runway to make it appear horizontal under nighttime conditions on both dynamic trials, as the model approached them, and on static trials, with the model stationary; 2) 12 pilots and 12 nonpilots performed the same task in dynamic trials while viewing the model in a dark field as before, and while viewing the model within a window which provided a stable visual frame of reference. Neither flying experience nor the visual frame of reference enhanced sensitivity to relative motion parallax. However, some errors were smaller in pilots, indicating that flying experience enhances other runway images cues. Direct judgments of approach angle magnitude indicated overestimation by an approximate factor of 2. These findings indicate large visual illusions in the nighttime situation and suggest that the ineffectiveness of relative motion parallax may be an important part of night approach problems.

Adolescent↗
PubMed1985

Auditory-visual perception of changing distance by human infants.

2 studies examined 5-month-old infants' sensitivity to auditory-visual specification of distance and direction of movement. In 1 experiment, infants were presented successively with 2 filmed events--1 of an automobile approaching, and the other of the same automobile driving away. A soundtrack that increased or decreased in amplitude was played along with each film, either in a match or mismatch condition. Infants did not show differential looking patterns related to the match or mismatch of auditory and visual information. In a second experiment, infants were tested using a paired preference technique. The films were shown side-by-side along with a single soundtrack appropriate to 1 of them. Looking time was monitored as before. These infants demonstrated visual preferences for the sound-matched films, evidently detecting the relationship between auditory and visual information when this procedure was used.

Auditory Perception↗
PubMed1991

[Objective assessment of disorders of visual perception following unilateral vestibular loss. Studies of the so-called Dandy symptom].

Visual ability and compensatory eye movements during defined vertical oscillation were investigated in 20 patients with unilateral lesions of labyrinthine function and in 20 normal subjects. Oscillation frequencies were performed at the rate of 1 to 1.5 Hz with an amplitude of 5 cm, comparative to head locomotions of a running person. In synchronism with this, the visual function was tested with Landolt rings. Patients complaining of subjective visual disturbance during walking and running, also presented a measurable blur of vision under test conditions. In addition, eye movements were recorded and classified into three types. However, these eye movements showed no relation to gaze function. Our results suggest that the otolith-ocular reflex may participate in adjusting the vertical eye position during vertical stimulations at low frequencies. The effect of visual disturbances in patients with labyrinthine lesions is explained by the "efference-copy" initially described by von Holst. The efference-copy is responsible for the neutralisation of provoked retinal perceptions.

Adult↗