Continuous hand movement induces a far-hand bias in attentional priority

Abstract

Previous research on the interaction between manual action and visual perception has focused on discrete movements or static postures and discovered better performance near the hands (the near-hand effect). However, in everyday behaviors, the hands are usually moving continuously between possible targets. Therefore, the current study explored the effects of continuous hand motion on the allocation of visual attention. Eleven healthy adults performed a visual discrimination task during cyclical concealed hand movements underneath a display. Both the current hand position and its movement direction systematically contributed to participants' visual sensitivity. Discrimination performance increased substantially when the hand was distant from but moving toward the visual probe location (a far-hand effect). Implications of this novel observation are discussed.

Effects of Hand Proximity and Movement Direction in Spatial and Temporal Gap Discrimination

“…The effect of Direction was significant for small gap trials, t (24) = 1.89, p < 0.05, d = 0.38 (one-tailed), and medium gap trials, t (24) = 1.79, p < 0.05, d = 0.36 (one-tailed), but not for large gap trials, t (24) < 1, ( Figure 2B ). For small gap trials, discrimination was better when moving toward [ M = 59.5% (small gap) and M = 71.3% (medium gap)] as opposed to away from the probe [ M = 56.7% (small gap) and M = 69.0% (medium gap)], thereby reproducing the effect of movement direction previously reported by Festman et al (2013a,b). …”

“…Based on the MVP hypothesis, we predicted improving temporal gap discrimination and impaired spatial gap detection as the hand approached the probe as compared to when the hand moves away from the probe. Furthermore, on the basis of the direction effect of Festman et al (2013a,b), we predicted better discrimination when moving toward the probe in both tasks.…”

“…They obtained evidence for superior performance when the hands were close together and thus directly below the letter probe in both settings, suggesting similar mechanisms for static postures and dynamic movements. In contrast, Festman et al (2013a), who investigated hand proximity effects in a letter discrimination task with continuous hand motions, found performance to be enhanced at far proximity when moving in the direction of the probe (direction effect). The interplay of near-hand and direction effects was examined in a subsequent study by Festman et al (2013b), in which the right hand moved below the display, while the left hand remained stationary on the side.…”

“…In particular, it provides an interesting and promising theory for hand proximity effects on visual selection but has so far only been tested with static hand postures. Previous studies by Festman et al (2013a,b) have established that attentional deployment is influenced differently by dynamically moving compared to static hands (direction effect). Therefore, the present study’s goal was to investigate the MVP hypothesis for continuous hand movements.…”

“…The question how hand proximity dynamically affects attentional deployment in ongoing movements has recently been addressed in a number of studies (Adam et al, 2012; Festman et al, 2013a,b). For instance, Adam et al (2012) investigated the effect of hand proximity in a letter discrimination task for both static hand postures and dynamic hand motions below a display.…”