Ricardo B. Morant

ADAPTATION TO PRISMATICALLY ROTATED VISUAL FIELDS.

The aftereffects of viewing a tilted field of lines differ from the effects of viewing a tilted field of objects. The difference is attributed to the fact that unlike isolated lines, objects have specifiable normal orientations.

The role of the felt position of the head in the audiogyral illusion

Abstract Previous work and theories on the audiogyral illusion ( AGI ) were discussed. An experiment was performed on four trained subjects in order to test the hypothesis that the AGI results from a change in felt head posture during angular acceleration. In general, the results supported the hypothesis.

A technique for making realistic three-dimensional images of objects

Two 151.8-cm-diam semicircular parabolic mirrors of optical quality are the essential components of an apparatus that creates highly realistic three-dimensional images of objects. The apparatus is being used to explore the relationship between vision and touch in infancy by creating a discrepancy between what is seen (a tangible-looking object) and what is felt. Previous attempts to study intersensory coordination in this manner have failed due to lack of realistic images. Other uses for the apparatus include the creation of illusory surfaces to study the development of expectations about the tangible surface properties of visible objects.

Inter-Field Tilt After-Effects

The study to be presented was designed to evaluate the assumption made by Gibson (1, 2 ) and other investigators (3, 5 ) that visual tilt a f ter -ef f~ts are localized; that is, that they are restricted to the area of the visual field corresponding to the part of the retina initially stimulated by a tilted inspection line. Two reasons make it appear necessary to investigate the validity of this assumption. The first has to do with the recent confirmation by Morant and Mistovich ( 4 ) of Gibsons (1, 2 ) finding that tilt after-effects are not restricted to the axis from which the inspection line least deviates. The existence of an inter-axial after-effect is paradoxical if the after-effect is, indeed, restricted. The second refers to the possibility that the demonstrations referred to in the literature to substantiate the assumption can be re-interpreted and shown to be not directly relevant to the question of restriction. This second reason will be more fully discussed in a later section. The experimental design used is essentially very simple. A single tilted inspection line is presented to one side of the median vertical of the visual field and a single test line to the opposite side. For purposes of comparison, trials in which the inspection and test lines are both to the same side of the median vertical are also included in the design.

The Archimedes Spiral and Diagnosis of Brain Damage

The validity of the Archimedes spiral as a diagnostic test of brain damage is examined experimentally. Results suggest that the different effects for normal and brain-damaged Ss reported in the literature can be attributed to the relative difficulty experienced by the brain-damaged S in maintaining fixation on the center of the spiral.