Virtual Hand Feedback Reduces Reaction Time in an Interactive Finger Reaching Task

Abstract

Computer interaction via visually guided hand or finger movements is a ubiquitous part of daily computer usage in work or gaming. Surprisingly, however, little is known about the performance effects of using virtual limb representations versus simpler cursors. In this study 26 healthy right-handed adults performed cued index finger flexion-extension movements towards an on-screen target while wearing a data glove. They received each of four different types of real-time visual feedback: a simple circular cursor, a point light pattern indicating finger joint positions, a cartoon hand and a fully shaded virtual hand. We found that participants initiated the movements faster when receiving feedback in the form of a hand than when receiving circular cursor or point light feedback. This overall difference was robust for three out of four hand versus circle pairwise comparisons. The faster movement initiation for hand feedback was accompanied by a larger movement amplitude and a larger movement error. We suggest that the observed effect may be related to priming of hand information during action perception and execution affecting motor planning and execution. The results may have applications in the use of body representations in virtual reality applications.

Fig 1. Experimental setup, visual feedback and experimental conditions.

(A) Subject in the MR scanner wearing a data glove and grasping the tube with the right hand. Visual feedback provided via mirror projection from a monitor. (B) Visual feedback consisted of the starting position (light-blue circle), movement cursor (skin coloured circle) and target (red circle) on grey background. (C) cursor feedback, (D) point light feedback, (E) cartoon hand feedback, and (F) virtual hand feedback.

Fig 2. Reaction time and standard error of the four types of visual feedback.

Cursor (red), point light (green), cartoon hand (cyan), and virtual hand (violet) conditions. Asterisks illustrate significant differences between conditions (p < 0.05).

Fig 3. Blink rate and average duration of fixation for the four movement and the four observation conditions.

Mean and standard error of A number of blinks per trial and B duration of fixation. Cursor (red), point light (green), cartoon hand (cyan), and virtual hand (violet) visual feedback.