Two Ways to Change Your Mind: Effects of Intentional Strength and Motor Costs on Changes of Intention.

Changes of Mind are a striking example of the human ability to flexibly reverse decisions after commitment to an initial choice, and to change actions according to circumstances. Previous studies of Changes of Mind largely focused on perceptual choices. Here we investigate reversals of voluntary, endogenous action decisions. In a novel version of the random-dot motion task, participants moved to a target that matched both the perceived dot-motion direction and an internally-generated intention (which colour target to move to). Movement trajectories revealed whether and when participants 1) perceived a change in dot-motion direction, or additionally 2) changed the colour that they chose to move to ( Change of Intention). Changes of Intention were less frequent in participants with strong colour intentions, as indicated by high performance costs in trials where perceptual information conflicted with the endogenous intention (Exp. 1). Additionally, Changes of Intention were more frequent when motor costs of intention pursuit were high (Exp. 2). These findings were simulated using an attractor network model that continuously integrates voluntary intentions, sensory evidence, and motor costs. This argues in favour of a unifying framework for dynamic decision-making processes, in which voluntary actions emerge from a dynamic combination of internal action tendencies and external environmental factors.