Embodiment and Its Influence on Informational Costs of Decision Density—Atomic Actions vs. Scripted Sequences

Abstract

The importance of embodiment for effective robot performance has been postulated for a long time. Despite this, only relatively recently concrete quantitative models were put forward to characterize the advantages provided by a well-chosen embodiment. We here use one of these models, based on the concept of relevant information, to identify in a minimalistic scenario how and when embodiment affects the decision density. Concretely, we study how embodiment affects information costs when, instead of atomic actions, scripts are introduced, that is, predefined action sequences. Their inclusion can be treated as a straightforward extension of the basic action space. We will demonstrate the effect on informational decision cost of utilizing scripts vs. basic actions using a simple navigation task. Importantly, we will also employ a world with “mislabeled” actions, which we will call a “twisted” world. This is a model which had been used in an earlier study of the influence of embodiment on decision costs. It will turn out that twisted scenarios, as opposed to well-labeled (“embodied”) ones, are significantly more costly in terms of relevant information. This cost is further worsened when the agent is forced to lower the decision density by employing scripts (once a script is triggered, no decisions are taken until the script has run to its end). This adds to our understanding why well-embodied (interpreted in our model as well-labeled) agents should be preferable, in a quantifiable, objective sense.

Quantifying embodiment towards building better robots based on muscle-driven models

“…It is based on the concept of relevant information and to identify how and when embodiment affects the decision density, in a minimalist scenario. Taking this research further, Polani et al [13] investigated how embodiment affects information costs when, scripts, defined as predefined action sequences, are introduced instead of atomic actions. It was demonstrated that that there are cases for which the introduction of scripts allows the agent to save decisions without processing more information for an average decision, thereby reducing information costs.…”

“…This is followed by comparing two main information-theoretic quantification methods. We discuss their applications by Haeufle et al [14] in quantifying the extent of embodiment in various levels of hierarchy in a neuro-musculoskeletal control system, and by Polani et al [13] to understand the impact of embodiment on informational costs.…”

Emergence of common concepts, symmetries and conformity in agent groups—an information-theoretic model

“…We then proceed to study a second type of symmetry, namely the influence of the agents’ mapping of sensors and actuators to actual changes in the environment; this mapping is identified with the concept of ‘embodiment’ in the parlance of [10]. Based on transformations of this embodiment, we now investigate ‘what the agent considers to be a symmetry of the environment’ from its internal perspective rather than from the perspective of externally given operations.…”

“…We assume the probabilistic sensor map p ( s t | r t ), translating a given world state into a sensor signal, and the actuator map p ( r t +1 | r t , a t ), causing a world state to change into a new one under the influence of an action, to be given a priori and invariant with respect to time t . Together, these two maps can be interpreted as forming the embodiment of the agent [10].…”

“…Here, the agent is modelled in discrete time, at each time step t sensing the world R t through its sensor S t and manipulating it through its actuator A t , by which the state of the world is changed in the following time step. We assume the probabilistic sensor map p(s t |r t ), translating a given world state into a sensor signal, and the actuator map p(r t+1 |r t , a t ), causing a world state to change into a new one under the influence of an action, to be given a priori and invariant with respect to time t. Together, these two maps can be interpreted as forming the embodiment of the agent [10].…”