Visual salience of 3D and 2D spoons determines S-R mapping and flanker effects

This study tested the hypothesis that affordances for grasping with the corresponding hand are activated more strongly by three-dimensional (3D) real objects than by two-dimensional (2D) pictures of the objects. In Experiment 1, participants made left and right keypress responses to the handle or functional end (tip) of an eating utensil using compatible and incompatible mappings. In one session, stimuli were spoons mounted horizontally on a blackboard with the sides to which the handle and tip pointed varying randomly. In the other, stimuli were pictures of spoons displayed on a black computer screen. Three-dimensional and 2D sessions showed a similar benefit for compatible mapping when the tip was relevant and a small cost of compatible mapping when the handle was relevant. Experiment 2 used a flanker task in which participants responded compatibly to the location of the handle or the tip, and spoons located above and below the target spoon could have congruent or incongruent orientations. The difference between 3D and 2D displays was not obtained in the flanker effect for reaction time. There was little evidence that 3D objects activate grasping affordances that 2D images do not. Instead, we argue that visual salience of the tip is the critical factor determining these correspondence effects.

Sidestepping spatial confounds in object-based correspondence effects: The Bimanual Affordance Task (BMAT)

Tucker and Ellis found that when participants made left/right button-presses to indicate whether objects were upright or inverted, responses were faster when the response hand aligned with the task-irrelevant handle orientation of the object. The effect of handle orientation on response times has been interpreted as evidence that individuals perceive grasp affordances when viewing briefly presented objects, which in turn activate grasp-related motor systems. Although the effect of handle alignment has since been replicated, there remains doubt regarding the extent to which the effect is indeed driven by affordance perception. Objects that feature in affordance-compatibility paradigms are asymmetrical and have laterally protruding handles (e.g., mugs) and thus confound spatial and affordance properties. Research has attempted to disentangle spatial compatibility and affordance effects with varying results. In this study, we present a novel paradigm with which to study affordance perception while sidestepping spatial confounds. We use the Bimanual Affordance Task (BMAT) to test whether object affordances in symmetrical objects facilitate response times. Participants ( N = 36) used one of three (left unimanual/right unimanual/bimanual) responses to indicate the colour of presented objects. Objects afforded either a unimanual (e.g., handbag) or a bimanual (e.g., laundry hamper) grasp. Responses were faster when the afforded grasp corresponded with the response type (unimanual vs. bimanual), suggesting that affordance effects exist independent of spatial compatibility.