Abstract
Detection of visual targets is enhanced in the grasping (functional) space of the hand relative to the non-grasping space (Lloyd et al, 2010; Reed et al 2010). We asked whether this advantage is specific to detection or whether more complex mechanisms such as discrimination also benefit. Using a Posner cueing paradigm we conducted two experiments to examine how functional hand space modulates exogenous visual spatial attention. In a between-groups design, participants positioned either their left or right hand at the corresponding lower corner of a monitor and with the palm in the prone (palm down) or supine (palm up) orientation. Targets (a yellow circle or a yellow triangle) were cued validly or invalidly (Cue duration 250ms; SOA 250ms; Target duration 250ms). They appeared on the monitor to the right or left of a fixation cross in the same or opposite hemispace as the hand. In experiment 1, using their other hand, participants responded to targets with a mouse click. Response times were faster to validly than invalidly cued targets, and there was a stronger cuing effect for targets occurring within perihand space compared with those in the opposite hemispace. Palm orientation did not modulate performance. In experiment 2, stimuli and hand position and orientation were the same, but this time participants discriminated between the circle and the triangle with a right or left mouse click. Supine palm orientation was associated with faster responses to targets appearing in the same hemispace as the hand. These findings indicate that the functional space of hands enables a relatively complex attention mechanism, discrimination rather than detection of targets. Lloyd, D. M., et al (2010). Brain and Cognition, 73(2), 102-109. Reed, C. L., Betz et al (2010). Attention, Perception, & Psychophysics, 72(1), 236-245.
Meeting abstract presented at VSS 2012