Adaptation to visual feedback delays on touchscreens with hand vision.

Direct touch finger interaction on a smartphone or a tablet is now ubiquitous. However, the latency inherent in digital computation produces an average feedback delay of ~ 75 ms between the action of the hand and its visible effect on digital content. This delay has been shown to affect users' performance, but it is unclear whether users adapt to this delay and whether it influences skill learning. Previous work studied adaptation to feedback delays but only for longer delays, with hidden hand or indirect devices. This paper addresses adaptation to touchscreen delay in two empirical studies involving the tracking of a target moving along an elliptical path. Participants were trained for the task either at the minimal delay the system allows (~ 9 ms) or at a longer delay equivalent to commercialized touch devices latencies (75 ms). After 10 training sessions over a minimum of 2 weeks (Experiment 1), participants adapt to the delay. They also display long-term retention 7 weeks after the last training session. This adaptation generalizes to a similar tracking path (e.g., infinity symbol). We also observed generalization of learning from the longer delay to the minimal-delay condition (Experiment 2). The delay thus does not prevent the learning of tracking skill, which suggests that delay adaptation and tracking skill could be two separate components of learning.