An active inference model of hierarchical action understanding, learning and imitation

We advance a novel computational model of the acquisition of a hierarchical action repertoire and its use for observation, understanding and motor control. The model is grounded in a principled framework to understand brain and cognition: active inference. We exemplify the functioning of the model by presenting four simulations of a tennis learner who observes a teacher performing tennis shots and forms hierarchical representations of the observed actions - including both actions that are already in her repertoire and novel actions - and finally imitates them. Our simulations that show that the agent’s oculomotor activity implements an active information sampling strategy that permits inferring the kinematics aspects of the observed movement, which lie at the lowest level of the action hierarchy. In turn, this low-level kinematic inference supports higher-level inferences about deeper aspects of the observed actions, such as their proximal goals and intentions. Finally, the inferred action representations can steer imitative motor responses, but interfere with the execution of different actions. Taken together, our simulations show that the same hierarchical active inference model provides a unified account of action observation, understanding, learning and imitation. Finally, our model provides a computational rationale to explain the neurobiological underpinnings of visuomotor cognition, including the multiple routes for action understanding in the dorsal and ventral streams and mirror mechanisms.

Infants’ and toddlers’ evaluations of helpers depend on their understanding of action goals

Although studies have found that infants prefer helpful individuals over unhelpful ones, the basis of such evaluations is unclear. If infants and toddlers, like adults, understand helping as fostering others’ goals, then their evaluations should depend on their ability to infer the goal of an agent in need of help. Here, 15-month-old toddlers and 8-month-old infants (n = 48) differentially evaluated acts of help, consistent with their developing understanding of means-end actions. In further experiments (n = 40), when a protagonist directly grasped an object, 8-month-old infants represented that goal and preferred an agent who facilitated it. These findings connect early evaluations of helping to action understanding.

Introduction

This chapter sets out the topic and structure of the book. Metameleia is the ancient Greek term for ‘regret’ in the sense close to the modern notion of ‘agent regret’. It is a painful self-reflexive emotion based on a revised assessment of a past action. Understanding regret is important as a way of understanding the nature of virtue, ethical improvement, and the possibility of moral dilemmas. Modern accounts of agent regret, including for example the account offered by Bernard Williams, share some characteristics of the accounts of metameleia offered by Plato, Aristotle, and the Stoics. But there are also important differences which we should note and try to explain.