Measurement of perceived oscillation

In earlier studies of perceived oscillation a comparison stimulus placed at a different distance and in a different direction from the observer than the Standard stimulus was used. The usual indicators were angles relating the turning positions, produced on a comparison stimulus, to a physical frame of reference, common for Standard and comparison. In three experiments where both Standard and comparison were “full-cuc,” the effect of different spatial arrangements was studied. Difference in distance did not affect the angles describing the response, nor did monocular or binocular vision, but difference in direction from the observer and the order of giving the two turning positions, combined with the position of the comparison stimulus before responding, had significant effects. The difference between Standard and comparison stimulus, which in an earlier series of experiments with artificial Standard stimuli had been rather large, was not very large for most conditions in the present experiments, where a real object was used as Standard stimulus. The correspondence was better, however, if another indicator, the angle describing the perceived extent of oscillation, was used. The spatial arrangements of Standard and comparison stimulus affect this indicator less than the indicators relating the perceived turning positions to the axes of the physical space.