Both hand position and movement direction modulate visual attention

Abstract

The current study explored effects of continuous hand motion on the allocation of visual attention. A concurrent paradigm was used to combine visually concealed continuous hand movements with an attentionally demanding letter discrimination task. The letter probe appeared contingent upon the moving right hand passing through one of six positions. Discrimination responses were then collected via a keyboard press with the static left hand. Both the right hand's position and its movement direction systematically contributed to participants' visual sensitivity. Discrimination performance increased substantially when the right hand was distant from, but moving toward the visual probe location (replicating the far-hand effect, Festman et al., 2013). However, this effect disappeared when the probe appeared close to the static left hand, supporting the view that static and dynamic features of both hands combine in modulating pragmatic maps of attention.

Keywords: covert attention; embodied cognition; hand dynamics; near-hand effect; perception.

Figure 1

Schematic illustration of the experimental setup. (A) Side view. (B) Bird's eye view of the two hands and their respective tasks. The right hand was always moving from right to left and back on a shelf under the display. Participants discriminated a probe letter (T or L) that was briefly displayed to the left or right of a fixation cross and was followed by an F-shape mask (not illustrated). Probes were displayed when the right hand reached positions R, C, or L during either leftward or rightwards movement. After motion completion the participant indicated the probe's identity by keyboard press with the visible left hand.

Figure 2

Probe discrimination performance. Performance on trials with right probe location (open circles) or left probe location (full circles), depending on hand position (x-axis, proportional to time on trial). Each circle denotes average performance (with SE).

Figure 3

Illustration of trial classification, using a trial with probe at position R as example (A). Performance in different hand positions for two probe locations. (B) Performance in discrimination left and right probe as a function of hand position and movement direction (C,D) Error bars show standard error of the mean.