An operant discrimination task allowing variability of reinforced response patterning

Five pigeons were trained to perform a discrimination task allowing variability of reinforced response patterning. The task consisted of moving a stimulus light within an 4x4 matrix of lights from the top left position to the bottom right position by pecking on two keys in succession in order to obtain a reinforcement. A peck on one key moved the light one position to the right and a peck on the other key moved it one position down. After preliminary training on alternating fixed-ratio 3 schedules of reinforcement, the birds could peck on either key in any order, but more than three responses on a key resulted in a blackout followed by the return of the stimulus light to the start position. Results indicate that initially the birds used a wide variety of response patterns to obtain reinforcement, but with continued practice, response patterns became more stereotyped.