Are Special Mechanisms Chosen in Short Experience-Based Identification of Degraded Geometric Forms?

Abstract

Perceptual performance schema are consistently prepared by human beings. Minimal ‘experience’ with pertinent stimulus attributes seem necessary. We presume that with new stimuli, a ‘linkage’ is formed with inner representations on the basis of commonly shared stimulus components. To investigate this hypothesis, we used ‘confusion stimuli’, ie degradations of five-corner and six-corner stars. These were presented within each of four paradigms: upright (u), rotated (10°; r), foveal/local viewing (A) or eccentric/global viewing (B), that is uA, uB, rA, and rB paradigms. Random presentation of stimuli prototypes preceded the stimulus so that in comparing the presented stimulus to one and the other prototype, the subject faced a 2AFC task. Series (4 to 6) each of 32 randomised paradigms were run on each of six subjects. The subjects keyed 5 or 6 on identifying one or the other stimulus. On the assumption that exposure time and/or acuity grades impose stimulus intensities, psychometric curves were derived by plotting probability of correct choice against either parameter. The results indicate that in hybrid paradigms such as the present uA and uB, or rA and rB subjects may use shared component strategy: ‘u strategy’ with uA and uB, ‘r strategy’ with rA and rB, shared A and B in generating viewpoint invariance. Similar log-linear psychometric curves and slopes for pairs of paradigms were obtained, and ‘transfer’ of learning presumably also based on shared stimulus properties was observed.