Action Prediction: a Multimodal Techniques Investigation of the Functional Relationship Between Belief-Tracking and Motor Processes

Anticipatory responses during action observation can indicate our expectation of an agent’s goals. The challenge is that social situations are often more complex, involving instances where we need to perceive and track an agent’s false belief to successfully identify and interpret the outcome to which an action is directed. One theoretical possibility is that if motor processes can guide how action goals are understood, it is conceivable—where that kind of goal ascription occurs in false-belief tasks—for motor representations to account for someone’s belief-like state. Multiple experiments were conducted to test that possibility. In Experiment 1A, adults (N = 42) were tested in a real-time interactive helping scenario, and the results showed that participants’ early mediolateral motor activity (leftwards–rightwards leaning on a balance board) and anticipatory gaze foreshadowed the agent’s belief-based action preparation. In Experiment 1B, adults (N = 39) did not show sensitivity to belief in their leaning or eye gaze when participants had to work out the chain of inferences governing the agent’s actions. The combined results suggest that small changes in the context can affect adults’ ability to spontaneously anticipate and to motorically represent an agent’s action. Experiment 2 presented the interactive helping scenario as a multi-trial computerized task. Experiment 2 measured the dynamics of adults’ leaning as well as hand trajectories as they attempted to reach a target object whilst an agent had a true or false belief about the object’s location (as a manipulation of motor representations, the agent was also shown as being motorically able or unable to grasp the target object). Replicating Experiment 1A, adults’ mediolateral balance during the action anticipation stage took into consideration an agent’s false- and true-belief about the target’s location. However, there was no evidence that the hand trajectories participants produced to provide a response were influenced by the agent’s beliefs. Manipulation of the agent’s ability to move did not affect participant’s mediolateral balance or the dynamics of their hand trajectories. While in Experiments 1A, 1B and 2, participants were shown the outcome to which the agent’s action was directed, in Experiments 3A (N = 51 adults), the task context was changed so that the agent did not present any outcome-directed action and participants were simply instructed to click as fast as possible on the box containing the target object. Experiment 3B (N = 55 adults) was the same as Experiment 3A, except that the task was presented in a go/no-go format. In Experiment 3A, there was no evidence that the agent’s belief influenced the degree to which participants’ mouse-movement trajectories deviated from a direct path to the object location. In Experiment 3B, the agent’s belief had a puzzling effect; participants’ mouse movements showed a more conspicuous attraction towards the full box (containing the target object) when the agent had a false-belief as compared to when the agent had a true-belief. While adults’ leaning, anticipatory looking and, more tentatively, hand movements, revealed some contribution of fast false-belief tracking, participants across the various experiments did not consistently correct the agent’s belief-induced mistake in their final helping action. This thesis will discuss the extent to which motor and mindreading processes may be variously integrated, and that adults may not necessarily use another’s belief during overt social interaction or find reflecting on another’s belief as being normatively relevant to one’s own choice of action.