ABSTRACT
The model proposed by Wing (1973) for the timing of interresponse intervals is tested on data from a Morse key tapping task, which required subjects to group their responses by twos, threes, or fours. Under these conditions, the serial covariance function of the interresponse intervals is found to differ systematically from that predicted by the model, demonstrating the existence of higher-order rhythmic groups in the underlying timing structure. Alternative extensions of the basic Wing model are presented that differ in the assumptions concerning the organization of the postulated timekeepers. Several tests of these models support a model assuming sequentially organized timekeepers, and give no evidence for hierarchic assumptions. To reconcile these findings with current views about the organization of complex behavior, it is suggested that serial ordering and timing of behavior are performed by different mechanisms.
