Know Your Body Through Intrinsic Goals.

Francesco Mannella,Gianluca Baldassarre,Eszter Somogyi,Lisa Jacquey,Vieri G Santucci,Kevin J O'Regan

doi:10.3389/fnbot.2018.00030

Abstract

The first “object” that newborn children play with is their own body. This activity allows them to autonomously form a sensorimotor map of their own body and a repertoire of actions supporting future cognitive and motor development. Here we propose the theoretical hypothesis, operationalized as a computational model, that this acquisition of body knowledge is not guided by random motor-babbling, but rather by autonomously generated goals formed on the basis of intrinsic motivations. Motor exploration leads the agent to discover and form representations of the possible sensory events it can cause with its own actions. When the agent realizes the possibility of improving the competence to re-activate those representations, it is intrinsically motivated to select and pursue them as goals. The model is based on four components: (1) a self-organizing neural network, modulated by competence-based intrinsic motivations, that acquires abstract representations of experienced sensory (touch) changes; (2) a selector that selects the goal to pursue, and the motor resources to train to pursue it, on the basis of competence improvement; (3) an echo-state neural network that controls and learns, through goal-accomplishment and competence, the agent's motor skills; (4) a predictor of the accomplishment of the selected goals generating the competence-based intrinsic motivation signals. The model is tested as the controller of a simulated simple planar robot composed of a torso and two kinematic 3-DoF 2D arms. The robot explores its body covered by touch sensors by moving its arms. The results, which might be used to guide future empirical experiments, show how the system converges to goals and motor skills allowing it to touch the different parts of own body and how the morphology of the body affects the formed goals. The convergence is strongly dependent on competence-based intrinsic motivations affecting not only skill learning and the selection of formed goals, but also the formation of the goal representations themselves.

Highlights

The first “object” that newborns start to play with is their own body, in particular by engaging with self-touch activities
The autonomous learning processes involving the acquisition of goals and of the motor capabilities to accomplish them under the guidance of contingency detection and competence-based intrinsic motivations converge to a steady equilibrium, consolidating the agent’s bodily knowledge that allows it to reach at will all different parts of the body with one of the two hands
In this work we investigated the hypothesis that self-generated goals and Intrinsic Motivations (IMs) may play an important role even in the early development of knowledge on own body and basic motor skills

Summary

Introduction

The first “object” that newborns start to play with is their own body, in particular by engaging with self-touch activities. Body Knowledge Through Intrinsic Goals movements become dominant (Thelen, 1995) This controlled motor activity (Piontelli et al, 2014) continues for many years after birth (Bremner et al, 2008) and presumably determines the formation of a “body schema” (Rochat and Striano, 2000), a sensorimotor map and a repertoire of actions that constitute the core of future cognitive and motor development. It seems plausible to consider self-touching as a self-sufficient activity: for instance, we do not need to include vision as part of the sensory input that determines early self-touch events This is justified first by the very poor use of vision by fetuses in the womb, and second by the fact that infants before 10 months of age seem to not use vision to localize external tactile stimulation on their body (Bremner et al, 2008; Ali et al, 2015)

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