Fig. 1

The history of unconstrained touchscreen behavior reflects on the performance of a simple sensorimotor task. a Touchscreen activity was recorded for 21 days and followed by laboratory measurements of sensorimotor variability. b The task required responding to tactile stimuli by pressing and releasing a micro switch, as fast as possible, with the thumb. Reaction time is the time from the sensory stimulus to the press-down action and movement time from the pressed position to the release. c–f Adjusted response plots. Movement time variability (σ) was inversely proportional to the typical rate at which the touchscreen was used (c) the number of Apps used (d) and the amount of activity on Non-social Apps (e). The variability was directly proportional to the amount of activity on Social Apps (f). Linear regression statistics is imprinted on the figures. Insert in figure c shows how the strength of the relationship with the typical rate varies as a function of the data collection period [assessed by using a 72 h sliding window, sliding with 12 h steps] and that the data collected 10.5 days prior to the experiment yielded the strongest correlation