Effects of Living in the up-down Inverted Visual World on Apparent Movement

The purpose of this study was to examine whether a change of perceptual framework may affect the occurrence of apparent movement. Apparent movement was observed by one subject living over four days in the prismatically inverted visual world, because this situation was considered as the operation in which the subject was forced to change the perceptual framework to adapt himself to the novel environment. Apparent movement with two points was measured in vertical and horizontal configurations before wearing and after removing the prism as well as while wearing it. Analysis showed significant effects of prism-wearing on the occurrence of apparent movement in both vertical and horizontal configurations. Although further elaboration is required, an hypothesis was suggested from the viewpoint of the loss of visual position constancy.

Motor-Transformation Learning

Motor-transformation learning theory asserts that people learn through experience what stimulus transformations are under the control of their behavior. More specifically, it asserts that the parameter values of certain predetermined transformation groups are learned. This theory was inferred, in the first place, from research on adaptation to optical rearrangement—in particular, from position-constancy adaptation in inverting-spectacles experiments, prism-displacement experiments, and in more recent computer-controlled feedback experiments. The detailed characteristics of position-constancy adaptation are found to be consistent with the theory. Diverse consequences radiate from the theory for other human abilities, both in perception and in memory retrieval. These diverse implications are tested in studies of (a) learning to manipulate ‘objects’ in an artificial computer-controlled visual space; (b) learning to compute, in the absence of overt action, the consequences of such action; (c) learning how to access the features of prior stimuli by the execution of motor actions.

Motion Parallax and Distance Estimation Underwater

The possible value of monocular motion parallax for improving distance perception underwater was investigated. Submerged Ss either kept their heads stationary or rotated their heads about a vertical axis while judging the distance of objects placed 4 to 15 ft. away. Both before and after training with feedback to increase accuracy of judgment, head movement did not significantly improve performance. Water turbidity and loss of position constancy are two probable reasons for the failure to replicate the positive results previously obtained in air.