Abstract

Active inference is an ambitious theory that treats perception, inference, and action selection of autonomous agents under the heading of a single principle. It suggests biologically plausible explanations for many cognitive phenomena, including consciousness. In active inference, action selection is driven by an objective function that evaluates possible future actions with respect to current, inferred beliefs about the world. Active inference at its core is independent from extrinsic rewards, resulting in a high level of robustness across e.g., different environments or agent morphologies. In the literature, paradigms that share this independence have been summarized under the notion of intrinsic motivations. In general and in contrast to active inference, these models of motivation come without a commitment to particular inference and action selection mechanisms. In this article, we study if the inference and action selection machinery of active inference can also be used by alternatives to the originally included intrinsic motivation. The perception-action loop explicitly relates inference and action selection to the environment and agent memory, and is consequently used as foundation for our analysis. We reconstruct the active inference approach, locate the original formulation within, and show how alternative intrinsic motivations can be used while keeping many of the original features intact. Furthermore, we illustrate the connection to universal reinforcement learning by means of our formalism. Active inference research may profit from comparisons of the dynamics induced by alternative intrinsic motivations. Research on intrinsic motivations may profit from an additional way to implement intrinsically motivated agents that also share the biological plausibility of active inference.

Highlights

  • Direct, non-variational Bayesian inference in combination with standard action selection schemes known from reinforcement learning as well as objective functions induced by intrinsic motivations

  • We believe that our framework can benefit active inference research as a means to compare the dynamics induced by alternative action selection principles

  • We have discussed the necessary posteriors following Equation (74). After this overview of some intrinsic motivations, we look at active inference

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Summary

INTRODUCTION

Active inference (Friston et al, 2012), and a range of other formalisms usually referred to as intrinsic motivations (Storck et al, 1995; Klyubin et al, 2005; Ay et al, 2008), all aim to answer a similar question: “Under minimal assumptions, how should an agent act?” More practically, they relate to what would be a universal way to generate behaviour for an agent or robot that appropriately deals with its environment, i.e., acquires the information needed to act and acts toward an intrinsic goal. Such a direct solution would allow a formally simple formulation of active inference without recourse to optimization or approximation methods, at the cost of sacrificing tractability in most scenarios To explore these questions, we take a step back from the established formalism, gradually extend the active inference framework, and comprehensively reconstruct the version presented in Friston et al (2015). Direct, non-variational Bayesian inference in combination with standard action selection schemes known from reinforcement learning as well as objective functions induced by intrinsic motivations. We believe that our framework can benefit active inference research as a means to compare the dynamics induced by alternative action selection principles It equips researchers on intrinsic motivations with additional ways for designing agents that share the biological plausibility of active inference. For example it may bring together the neurobiological plausibility of active inference and the constitutive autonomy afforded by empowerment

RELATED WORK
STRUCTURE OF THIS ARTICLE
NOTATION
PERCEPTION-ACTION LOOP
PA-loop Bayesian Network
Assumptions
INFERENCE AND COMPLETE POSTERIORS
Generative Model
Bayesian Complete Posteriors
Connection to Universal Reinforcement Learning
Approximate Complete Posteriors
Intrinsic Motivation and Action-Value
Deterministic and Stochastic Action Selection
Intrinsic Motivations
ACTIVE INFERENCE
APPLICATIONS AND LIMITATIONS
10. CONCLUSION
NOTATION TRANSLATION TABLES
Full Text
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