Effect of Tapping Bout Duration During Freely Chosen and Passive Finger Tapping on Rate Enhancement.

The present study investigated whether the duration of the first tapping bout, which could also be considered 'the priming', would play a role for the occurrence of the behavioral phenomenon termed repeated bout rate enhancement. Eighty-eight healthy individuals were recruited. Sixty-three of these demonstrated repeated bout rate enhancement and they were assigned to two different groups, which performed either active or passive tapping as priming. The durations of the first tapping bouts, which acted as priming, were 20, 60, 120, and 180 s. Following the first bout there was a 10 min rest and a subsequent 180 s tapping bout performed at freely chosen tapping rate. Vertical displacement and tapping force data were recorded. Rate enhancement was elicited independently of the duration of the first bout in both groups. Rate enhancement occurred without concurrent changes of the magnitude of vertical displacement, time to peak force, and duration of finger contact phase. The peak force was reduced when 180 s of tapping had been performed as priming. The increased tapping rate following priming by as little as 20 s active or passive tapping, as observed here, is suggested to be a result of increased net excitability of the nervous system.