Perception of fragmented images of three-dimensional objects as the observation angle changes.

Recognition thresholds for incomplete two-dimensional images of three-dimensional objects were measured as the observation angle was changed. A new experimental psychophysical method was developed and programmed for this purpose, this being a modification of the Gollin test, which measures perception thresholds of incomplete outline images. After training to a stimulus alphabet, observers' responses were found to be invariant to changes in the observation angles of three-dimensional objects from 15 degrees to 60 degrees. It is suggested that possible algorithms for the formation of models of three-dimensional images in the human visual system do not operate on the basis of simple section, but involve invariance mechanisms.