Sixty Ss learned a motor task (pressing sequences of levers arranged in a spatial pattern) in response to letters as stimuli. The degrees of prior training were 0, 10. 30, 50, and 100 errorless trials on the training task, with 12 Ss in each of these groups. The transfer task simultaneously tested 4 different conditions, 3 transfer and a 4th condition which controlled for warm-up. The findings were: (1) Learning to make a new response to an old stimulus showed an initial increase in negative transfer followed by a return to zero transfer for the highest degree of overlearning of the training task, (2) Learning to make an old response to a new stimulus showed increasing positive transfer as degree of original training was increased, (3) Learning to make an old response to an old stimulus, when these had not been previously paired, showed no significant effects at low de-grees of training, but significant positive transfer at the highest degree of overlearning. The relationship of these data to a theoretical framework; (4) dealing with response factors in human learning and overlearning was discussed.