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Biomedical subjects

G Mather

Publications and source records attributed to G Mather.

42 records · Page 3Linked to original sources
PubMed1984

Screening for color blindness using optokinetic nystagmus.

Red/green luminosity ratios were determined by a new method. A special colored grating of red and green bars appeared to move to the left (or right) when the red bars were darker (or lighter) than the green bars. Optokinetic nystagmic eye movements (OKN) elicited by this stimulus could be measured photoelectrically, or by directly watching the subject's eyes. When the red/green ratio passed through equiluminance, the direction of apparent movement (AM) and of OKN reversed in direction. Protans needed more red than normals to reach equiluminance, and deutans needed more green. This OKN method might be applied to nonverbal subjects such as infants and animals.

Color Vision Defects↗
PubMed1980

The movement aftereffect and a distribution-shift model for coding the direction of visual movement.

At present the only widely accepted explanation for the movement aftereffect is Sutherland's so-called ratio model, which states that motion is coded by taking the ratio between the outputs of detectors tuned to opposite directions. However, as yet there have been few attempts to derive predictions from the model in the context of movement aftereffects and test them experimentally. This paper reportws experiments which attempt to determine whether such a simple model is sufficient, or requires additional assumptions which recast it in a form more akin to the distribution-shift models used in other domains (which assume comparisons between outputs in the whole population of direction detectors, rather than just those tuned to opposite directions). These experiemtns examined the interactive effects of two simultaneous directions on subsequent aftereffect durations and directions. The results obtained are difficult to explain in terms of a simple ratio model but can be incorporated into a more complex distribution-shift type model.

Adaptation, Ocular↗