Sleep Deprivation Influences Trial-to-Trial Transfer but Not Task Performance.

Previous research has shown that sleep deprivation can affect emotions and some cognitive functions. However, research on how sleep deprivation influences the visuomotor memory have rarely been reported. In the current study, a Fitts' Law task was used to investigate how movement and the visuomotor memory are affected under the condition of sleep deprivation. Experiment 1 had 36 participants (15 males, mean age = 21.61 years) complete the same Fitts' Law task 10 days apart under standard conditions. Experiment 2 had five participants (three males, mean age = 27.2 years) complete the task after 7 days of sleep deprivation, then complete it again after 10 days without sleep deprivation. Experiment 1 demonstrated the stability of the trial-to-trial effects. Experiment 2 showed that the previous trial (n) exerted no effect on the current trial (n + 1) under the conditions of sleep deprivation (p = 0.672). However, the effect was observed after 10 days without sleep deprivation (p = 0.013). This suggests that sleep deprivation did not affect task performance but influenced the transfer of the trial history. Future studies are required to investigate the effect of sleep deprivation with more participants.

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.

Fitts' Law is modulated by movement history.

Fitts' Law is one of the most robust and well-studied principles in psychology. It holds that movement time (MT) for target-directed aiming movements increases as a function of target distance and decreases as a function of target width. The purpose of this study was to determine whether Fitts' Law is affected not only by the demands of the target on the current trial but also by the requirements for performance on the previous trial. Experiments 1 and 2 examined trial-to-trial effects of varying target width; Experiment 3 examined trial-to-trial effects of varying target distance. The findings from Experiments 1 and 2 showed that moving a finger or cursor towards a large object on a previous trial shortened the movement time on the current trial, whereas the opposite occurred with a small object. In contrast, target distance on the previous trial had no effect on movement time on the current trial. These findings suggest that performance on trial n has a clear and predictable effect on trial n+1 (at least for target width) and that Fitts' Law as it is normally expressed does not accurately predict performance when the width of the target varies from trial to trial.