Complex visual discrimination of tridimensional patterns in rats: progressive learning improves discriminative and recognition capacities

The purpose of these experiments was to evaluate the rat's discriminative capacities when facing tridimensional patterns. The behavioral approach involved 3 steps: (1) After establishing a brightness discrimination in a Y-maze (S+ = dark, S- = bright), tridimensional objects were introduced into the goal boxes. (2) Brightness differences were gradually attenuated during the course of the fading procedure and correct responding to the tridimensional patterns was obtained. (3) This procedure had a second fading phase where configurational differences between these patterns were progressively reduced. All animals trained with this method of successive approximations learned the discrimination to a 90% criterion; whereas control animals, given the same complex discrimination without any shaping procedure, failed to learn. These experiments show that success or failure in the acquisition of a visual task is specific to the training method used. Our fading procedure produced complex discrimination behavior.