It’s been repeatedly shown that pictures of graspable objects can facilitate visual processing and motor responses, even in the absence of reach-to-grasp actions, an effect often attributed the concept of affordances, originally introduced by Gibson (1979). A classic demonstration of this is the handle compatibility effect, which is characterised by faster reaction times when the orientation of a graspable object’s handle is compatible with the hand used to respond, even when the handle orientation is task irrelevant. Nevertheless, whether faster RTs are due to affordances or spatial compatibility effects has been significantly debated. In the proposed studies, we will use a stimulus-response compatibility paradigm to investigate firstly, whether we can replicate the handle compatibility effect while controlling for spatial compatibility. Here, participants will respond with left- or right-handed keypresses to whether the object is upright or inverted and, in separate blocks, whether the object is red or green. RTs will be analysed using repeated-measures ANOVAs. In line with an affordance account, we hypothesise that there will be larger handle compatibility effects for upright/inverted compared to colour judgements, as colour judgements do not require object identification and are not thought to elicit affordances. Secondly, we will investigate whether the handle compatibility effect shows a lower visual field (VF) advantage in line with functional lower VF advantages observed for hand actions. We expect larger handle compatibility effects for objects viewed in the lower VF than upper VF, given that the lower VF is the space where actions most frequently occur.
Interhemispheric vs. stimulus-response spatial compatibility effects in bimanual reaction times to lateralized visual stimuli
