Putting in the effort: Explicit effort may not influence perceptuomotor decision-making


Humans often make decisions that are enacted by the action system. For example, humans use reach-to-grasp movements when making perceptuomotor decisions between and obtaining donuts of varying perceived quality. Recent work suggests that the characteristics of each action alternative may influence the associated decision-making process – biases away from perceptuomotor alternatives associated with high effort have been reported when participants are unaware of the effort differences between responses. The present study examined if perceptuomotor decisions were influenced by explicit, as opposed to implicit, reaching effort differences. Random dot motion stimuli were presented in which most dots moved in random directions and varying percentages of remaining dots moved coherently left- or rightward. Participants reported leftward motion judgements by performing leftward (or left hand) reaching movements and rightward motion judgements by performing rightward (or right hand) reaching movements on a tabletop. A resistance band was affixed to participants’ wrists and to the edge of the tabletop in different configurations. The configurations ensured that one movement/ motion direction judgement always required stretching of the band and, therefore, relatively more effort than the alternative movement. Across four experiments, the response context (i.e., selecting directions within a limb or selecting between limbs) and the effort difference between responses was manipulated. Overall, no experiment revealed a consistent bias away from the perceptuomotor decision associated with high effort. It is concluded that explicit effort as induced by a resistance band may not influence perceptuomotor decision-making and may point to a contextual influence of action effort on perceptuomotor decision-making.