Do hands attract attention?

Lateral peri-hand bias affects the horizontal but not the vertical distribution of attention

It has been demonstrated that humans exhibit an attention bias towards the lower visual field (e.g., faster target detection for targets appearing below eye level). This bias has been interpreted as reflecting the visual motor demand in near space below eye level. In this study, we examined whether this spatial bias could be affected by participants' hand position at the time of testing. Specifically, if the hand position is held at eye level at the time of target detection, whether the bias toward the lower visual field would be reduced if the bias is directly related to the motor demand at the time of testing. Using a modified spatial cueing paradigm, in Experiment 1, we found a downward bias in reaction time measures and cueing effects in a target detection task. In Experiment 2, using the same stimulus used in Experiment 1, we compared attention performance when participants' dominant (right) hand was positioned close to the right side of the visual display with the conditions where their hand was in their laps. We revealed that despite an influence on the horizontal distribution of attention (lateral peri-hand effect), the downward bias in attention remained regardless of the hand position. This revealed that lateral peri-hand manipulation is insufficient to override the attention advantage for stimuli appearing in the lower visual field.

Interacting hands draw attention during scene observation

In this study I examined the role of the hands in scene perception. In Experiment 1, eye movements during free observation of natural scenes were analyzed. Fixations to faces and hands were compared under several conditions, including scenes with and without faces, with and without hands, and without a person. The hands were either resting (e.g., lying on the knees) or interacting with objects (e.g., holding a bottle). Faces held an absolute attentional advantage, regardless of hand presence. Importantly, fixations to interacting hands were faster and more frequent than those to resting hands, suggesting attentional priority to interacting hands. The interacting-hand advantage could not be attributed to perceptual saliency or to the hand-owner (i.e., the depicted person) gaze being directed at the interacting hand. Experiment 2 confirmed the interacting-hand advantage in a visual search paradigm with more controlled stimuli. The present results indicate that the key to understanding the role of attention in person perception is the competitive interaction among objects such as faces, hands, and objects interacting with the person.

Experimental Evidence of Structural Representation of Hands in Early Infancy

Hands convey important social information, such as an individual's emotions, goals, and desires, are used to direct attention through pointing, and are a major organ for haptic perception. However, very little is known about infants' representation of human hands. In Experiment 1, infants tested in a familiarization/novelty preference task discriminated between images of intact hands and ones that contained first-order structure distortions (i.e., with locations of fingers altered to result in an unnatural configuration). In Experiment 2, infants tested in a spontaneous preference task exhibited a preference for scrambled hand images over intact images, indicating that 3.5-month-olds have gained sufficient sensitivity to the configural properties of hands to discriminate between intact versus scrambled images without any training in the laboratory. In both procedures, infants' performance was disrupted by inversion of images, suggesting that infants' performance in the upright conditions was not based on low-level features. These results indicate that sensitivity to the structure of hands develops early in life. This early development may lay the foundation for the development of the functional use of hand information for social communication.