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Abstract

This thesis is concerned with the comparison of monocular and binocular vision. Previous studies are reviewed and the aims and methods of the present investigation have been stated. Psychophysical experiments are described, the aim of which is to quantify the relative merits of monocular and binocular vision by the measurement of visual thresholds. Three tasks are involved: contrast detection, visual acuity and recognition, twenty subjects undergoing each task.

The contrast detection experiment shows that over a range of ambient luminances from 10(-1) to 4.7 x 10(-5) Cd M (-2) the monocular/ binocular threshold ratio can be as high as 1.72 and is not less than 1.35. The ratio is not affected by increasing the stimulus distance from 1.3 metres to infinity nor by changing the shape of the stimulus from circular to square. The results show definite evidence for physiological summation as opposed to simple probability summation as suggested in previous literature.

The comparison of binocular with monocular acuity over a range of luminances from 7.1 to 3.6 x 10 (-4) Cd M(-2) shows an increasing binocular superiority as the contrast between stimulus and background is decreased. The binocular to monocular acuity ratio increases from 1.06 for a target to background contrast of 0.70 to 1.54 as the contrast is decreased to 0.01. These ratios are increased if the ambient luminance is decreased.

The recognition experiment involves the comparison of monocular and binocular contrast thresholds for the recognition of letters of the alphabet. The range of luminances considered is from 7.1 to 3.6 x 10 (-4) Cd M (-2). The results are very similar to those obtained in the detection experiment except that the ratios are significantly lower throughout the luminance range.

A subsidiary experiment indicates that monocular fatigue involved in a prolonged contrast detection task, although causing a subject to have less confidence in his results with increasing time, is not reflected in the actual results obtained.

Publication Type:	Thesis (Doctoral)
Subjects:	Q Science > Q Science (General) R Medicine > RE Ophthalmology
Departments:	School of Health & Medical Sciences > Department of Optometry & Visual Science School of Health & Medical Sciences > School of Health & Medical Sciences Doctoral Theses Doctoral Theses

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