"Can't touch this! ": The influence of act-ability on gaze cueing of attention in an upper-limb reaching task


Social cues, such as the direction of eye gaze and pointed fingers, can increase the prioritization of specific locations and potentially affect movement execution. Previously, we used a manual reaching task and showed that, although both gaze and pointing cues could alter target prioritization (reaction times [RTs]), only pointing cues affected action execution (trajectory deviations). This discrepancy could be attributed to the fact that the gaze cue was conveyed through a disembodied head; hence, there was no potential for target interaction with a body part (i.e., hands). In this study, participants were presented with a torso and upper limbs along with the head, introducing the potential for the gaze model to interact with the targets. The image of a male was presented in the center of the screen with his arms and hands extended laterally underneath the two potential target locations. After the model shifted his gaze to one of the target locations, the target was presented at one of three stimulus onset asynchronies ([SOA]; 100, 350, or 850ms). Participants would reach to the target that appeared independently of the gaze direction. Temporal (RT) and spatial properties (reach trajectories) of the movements to cued and uncued targets across different SOAs were analyzed. RT was only shorter in the cued condition for the 350ms SOA. We did not find any effects within the reach trajectories. Our results confirmed our previous finding that eye gaze cues only affected attention, but not action execution, even when the model has an upper body.

Acknowledgments: We want to thank Jacob Burgess for helping to collect portions of the data presented in this study.