How long is the interval over which trial-to-trial effects on Fitts' Law task can operate?

Fitts' Law is a well-studied principle in psychology which holds that movement time (MT) varies with the size and distance of a target across a wide range of tasks. In a recent study, the authors demonstrated that performance on a current trial in a Fitts' Law paradigm is affected by what happens during the previous trial (Tang et al. in Psychon Bull Rev 25(5):1833-1839, 2018). The aim of the present study was to explore how long this trial-to-trial transfer might last and whether or not the transfer would occur between the left and right hands. A series of experiments was carried out using discrete trials, a paradigm in which the current authors and others have previously established that Fitts' Law operates (Fitts and Peterson in J Exp Psychol 67(2):103-112, 1964; Tang et al. 2018). Three inter-trial intervals (3 s, 4 s, and 5 s) were used in separate testing sessions, the order of which was counterbalanced across participants. In addition, trial-to-trial transfer was tested within a single hand and between hands. The results demonstrate that transfer from one trial to the next could bridge 4 s when either the right or the left hand was used and would disappear by 5 s. Moreover, the effect transferred between the two hands. The endpoint accuracy of the current trial was not affected by the previous trial. These findings suggest that the trial-to-trial effect reduces over time and that the transfer of sensorimotor memory or the task set is independent of the particular hand used.