[Practice effect and transfer in orientation discrimination reaction time].

Two experiments were carried out measuring DRT. Two stimuli, horizontal-vertical and oblique ones were used, and four subjects were required to discriminate them in two categories as quickly as possible. In Experiment 1, the stimulus was presented in peripheral retina, every subjects showed a marked oblique effect at the outset. This effect decreased with proceeding sessions. After six sessions (600 trials), the results of these subjects were compared with those of naive control subjects in direct vision, in Experiment 2. The Experimental Group showed only a little oblique effect as contrasted with the Control Group. Such practice effect and the transfer effect couldn't be attributed to the functional anisotropy of the orientation analyzers in the visual cortex, and consequently, a cognitive approach was suggested.