Shifting visual attention in stereographic displays: a time course analysis

According to a growing number of studies, the stereographic presentation of three-dimensional information improves overall performance relative to displays with only monocular depth cues. Based on studies using real-world, three-dimensional stimuli, however, the efficiency (i.e., speed) of shifting attention between objects located at different depths is impaired relative to that of attention shifts between objects located at the same depth. In the present study we tested whether similar impairments occur when attention is shifted in stereographic space. We compared the time course of attention shifts across and within depth planes using a spatial cuing task. Contrary to the results from studies of real-world stimuli, we found no difference between the time course of within-plane and across-plane attention shifts.

The moon illusion revisited

In two experiments, the apparent size of a simulated horizon moon was measured as a function of the location of visible texture in the natural vistas against which it appeared. Size was found to increase as the visible scene extended farther into the distance and to decrease as the moon rose above the vista of surface texture. In the second experiment, the observers' eye accommodation distances to various scenes were also measured with a laser optometer, and after appropriate transformations, size judgments were found to correlate 0.89 with measured accommodation values, thereby suggesting the hypothesis that the fabled moon illusion is mediated by the oculomotor adjustments of visual accommodation.