Predicting visual search for abnormal color vision with perceptual models of color deficient vision

Abstract

Performance on a visual search task depends on the conspicuity of the target in relation to the distracters. If these have different colors, performance can reveal the perceptual structure of the color space. The aim of this work was to test how perceptual models of color deficiencies predict the performance of dichromats and anomalous trichromats on a search paradigm. Brettel’s transformation and a transformation of the stimuli based on the anomalous photopigments proposed by DeMarco et al. were the models used. Stimuli were presented on a calibrated CRT monitor driven by a VSG2/3 graphics card. The stimuli consisted of one target (diamond shaped) among 150 distracters (squares, circles and triangles). The target was always displayed at 1-deg from the center of the screen and the distracters were randomly spread across 8x7 deg. In the normal condition, the colors of the target and distracters were selected in 48 directions around standard illuminant C in CIE L*a*b* color space and the hue angle between target and distracter was always 60-deg. All distracters had the same color but randomized luminance in the range 9.5-17 cd/m². Observers were instructed to find a diamond-shaped target among the distracters and signal its presence as quickly as possible using a response box. The experiment was carried out by three deuteranopes, five protanopes, four deuteranomalous and three protanomalous. In the simulation condition, corresponding to Brettel’s and DeMarco’s transformation of the stimuli of the normal condition, seven normal color observers participated in the experiment. Results show high correlation for deuteranopes (r=0.82) and protanopes (r=0.83) and low correlation for deuteranomalous (r=0.45) and protanomalous (r=0.15). Additionally, both dichromats and anomalous trichromats took longer than normal observers tested with the simulated stimuli. These results suggest that Brettel’s model predicts well dichromats perception and DeMarco transformation failed to predict anomalous trichromats perception.

Meeting abstract presented at VSS 2015