Deciding while moving: Cognitive interference biases value-based decisions.

When people act, they repeatedly have to make value-based decisions about the further course of actions. For example, when driving on the highway, they must decide whether to overtake other cars by changing lanes to arrive at their destination quicker; concurrently, they are required to stay on their momentary lane by controlling the steering wheel. Embodied choice models predict that concurrent action execution modulates value-based decisions. Here, we examined whether value-based decisions are influenced by a change of action costs and/or cognitive interference between concurrent actions and decision making. In a novel, computerized multilane tracking task paradigm, participants (N = 50) controlled a cursor moving on one of three horizontal lanes. During tracking (concurrent action), participants had to switch to other lanes to avoid obstacles or collect rewards (value-based decisions). The action costs associated with a lane switch depended on the cursor position relative to the currently tracked lane, and this relationship varied between conditions. Results showed that value-based lane switching decisions were biased by the cursor state. While this influence was partly attributed to minimizing action costs, a considerable part of the influence could be attributed to cognitive interference. Our findings provide further evidence for embodied choice models, showing that both cognitive interference as well as action costs bias value-based decisions.