Biomedical subjects

T Buckingham

Publications and source records attributed to T Buckingham.

21 records · Page 2Linked to original sources

PubMed1986

Displacement thresholds for continuous oscillatory movement: the effect of oscillation waveform and temporal frequency.

Displacement thresholds for continuous oscillatory movement of a grating, subtending 2 cycle deg-1, were measured for square-, triangular- and sine-wave oscillation over the frequency range 1-20 Hz. Without reference lines, thresholds were highly dependent upon temporal frequency and oscillation waveform. With reference lines, thresholds were dependent upon oscillation waveform but not frequency. Greatest sensitivity was shown to square-wave oscillation and least to triangular-wave. Results are discussed in terms of velocity- and displacement-analysing systems. Increasing the spatial frequency of the sinusoidally oscillating grating had little effect on displacement thresholds.

Humans↗

PubMed1985

The influence of luminance on displacement thresholds for continuous oscillatory movement.

Displacement thresholds were determined for a sinusoidally-modulated contrast grating, having a spatial frequency of 2 c/deg, whose mean luminance could be varied. The grating underwent continuous oscillatory simple harmonic motion. Displacement thresholds were determined for frequencies of 1, 3, 5, 7 and 10 Hz using the method of limits for each mean grating luminance of 3.8, 8.9, 26, 62 and 134 cd/m2. With low oscillation frequencies a marked reduction in sensitivity is produced by reducing the mean luminance of the grating. This is not the case with higher oscillation frequencies when mean luminance has little effect upon sensitivity.

Eye Movements↗

PubMed1985

The influence of adapting velocity and luminance on the movement after-effect.

The response of movement-sensitive mechanisms to both velocity and luminance may be investigated by means of the movement after-effect (MAE). A high contrast (98%) drifting grating having a spatial frequency of 1c deg-1 was used with four adapting velocities of 0.90, 2.87, 4.70 and 7.55 deg sec-1 to confirm their significant effect on initial MAE velocity (F = 29.83, P less than 0.01) and duration (F = 12.36, P less than 0.01). Four mean luminance levels of 4.5, 12.6, 42.9 and 126 cd m-2, spanning 1.5 log units of illumination, demonstrate its subtle effect on both initial MAE velocity (F = 4.11, P less than 0.01) and duration (F = 3.00, P less than 0.05). It is argued that adaptation of movement-sensitive mechanisms is more accurately reflected by the initial MAE velocity than its duration. The tracking technique which was employed, whilst accurate at low velocities, progressively underestimates the MAE velocity with increasing velocity. With a velocity of 1.2 deg sec-1 the under-estimate is 12%, rising to 23% at 2 deg sec-1. The tracking procedure, however, remains a reliable technique for assessing low velocity MAEs.

Adaptation, Ocular↗