The impact of motor responses on serial-pattern learning.

Subjects are able to learn even very complex serial patterns in serial-reaction-time tasks. The investigation of the learning processes behind this phenomenon has yielded contradictory results. Some studies have come to the conclusion the subjects had learned the sequence of stimuli. Other studies have assumed that the sequence of responses had been learned or a combination of both stimuli and responses. The present experiments stress the impact of motor responses on serial-pattern learning. The subjects had to respond to serial targets that were presented within a matrix of distractors. The position of each target could be predicted from the identity and position of the previous target. If the subjects were to learn this pattern, they would be able to speed up the search for the target and give faster responses. The results indicated that the relation between the target identity and the position of the next target was acquired much better by those subjects who had to respond to each target with a special motor response. If the same response was required for the relevant targets, knowledge of the rule was somewhat fragmentary. To explain these results, mechanisms of motor learning and motor planning are discussed. It is assumed that learning of the rules occurs if the position changes appear to be effects of different motor responses.