SPEED DISCRIMINATION THRESHOLDS FOR FIRST-ORDER AND 2ND-ORDER BARS AND EDGES

Speed discrimination thresholds were measured for first- and second-or der Gaussian bars and edges as a function of speed and the spatial sca le of the modulation signal. Discrimination thresholds were generally higher for the second-order patterns when compared with modulations of luminance. There were no systematic effects of variations in the widt h of the bars and edges. The results are discussed in relation to mech anisms for the explicit recovery of contrast modulations and the influ ence of the form of the carrier signal on visual performance in second -order motion tasks. (C) 1997 Published by Elsevier Science Ltd.