Stimulus and response repetition effects for naming letters at two response-stimulus intervals

Upper- and lower-case letters of the alphabet were presented sequentially to S using .2-sec and. 7-sec RSIs. Reaction times for naming the letters were recorded for three classes of stimulus events: the letter was identical in form and name to the immediately preceding one (stimulus repetitions); the letter had the same name but a different form than the preceding one (response repetitions); and the letter was different in form and name from the preceding one (nonrepetitions). The results showed a significant advantage of SR over RR that decreased as the RSI increased and depended on the similarity of the upper and lower cases for the particular letters. These results are comparable to those obtained in letter-matching studies. A model to account for the results is proposed.