Abstract
In a recent study by Tucker and Ellis (1998) participants saw photographs of familiar objects, and made a judgment about their (up/down) orientation. Each object had an affordance (e.g., handle) that was on the right or left. Responses were faster if the object's handle was on the same side as the response hand. Although Tucker and Ellis claim that it is the coding of the object as graspable that accounts for these findings, it is not clear what property of these asymmetrical stimuli was differentially affecting left or right responses.
A simple shift in attention to one side will facilitate responses made on the corresponding side. Perhaps the affordances of objects, being salient properties, draw attention to one side of the image and produce stimulus-response compatibility.
Using the stimulus-response compatibility paradigm, we investigated the coding of asymmetrical objects more closely. We began with simple, abstract shapes, larger on either the left or right side. Responses were faster when made on the same side as the larger side of the object (p<.05). In a second study, an arrow was added to the smaller side of the object. Responses were faster when made on the same side as the arrow (p<.05).
Our results suggest that objects can be coded, or attention shifted, by various cues. These can be perceptual (center of mass), cognitive (direction of arrow) and motor (affordances). In further studies, we investigated what properties of the task or the stimuli would cause these different cues to be employed.