The first prior: From co-embodiment to co-homeostasis in early life

Highlights

• The paper is a predictive processing investigation of perceptual experiences in utero.

• Primitive experiences are co-embodied in a strong ontological sense.

• Homeostatic self-regulation first emerges within and through another human body.

• The concepts of co-embodiment and co-homeostasis are introduced.

• The ‘first prior’ is strongly dependent on co-embodiment and co-homeostasis.

Abstract

The idea that our perceptions in the here and now are influenced by prior events and experiences has recently received substantial support and attention from the proponents of the Predictive Processing (PP) and Active Inference framework in philosophy and computational neuroscience. In this paper we look at how perceptual experiences get off the ground from the outset, in utero. One basic yet overlooked aspect of current PP approaches is that human organisms first develop within another human body. Crucially, while not all humans will have the experience of being pregnant or carrying a baby, the experience of being carried and growing within another person’s body is universal. Specifically, we focus on the development of minimal selfhood in utero as a process co-embodiment and co-homeostasis, and highlight their close relationship. We conclude with some implications on several critical questions fuelling current debates on the nature of conscious experiences, minimal self and social cognition.

Introduction

Recent years have witnessed an ‘embodied turn’ in examining perception, cognition and action from a situated and embodied viewpoint (Varela et al., 1991, Gallagher, 2000, Thompson, 2007, De Jaegher and Di Paolo, 2007, Chemero, 2009). The idea basic idea is that our bodies’ survival within a wider and potentially threatening physical and social environment lies at the core of our perceptual experiences and cognitive processes. The embodied cognition approach outlines the idea that perception and cognition are first and foremost embodied activities (Noë, 2004, Sheets-Johnstone, 2011). In this view, cognition is “the enactment of a world and a mind on the basis of a history of the variety of actions that a being in the world performs” (Varela et al., 1991:9, our italics).

The idea that our ongoing perceptions, cognitive processes and actions are influenced by prior events and experiences has recently received substantial support and attention from the proponents of the Predictive Processing (PP henceforth) and Active Inferences framework¹ (AIF henceforth) in philosophy and computational neuroscience (Friston, 2005, Clark, 2013, Hohwy, 2013, Fotopoulou, 2015). The basic starting point is the idea that humans are biological agents that “emerge as proactive survival-enabled prediction machines” (Clark, 2013:1).

In order to keep track of the survival- and reproduction-relevant bodily and worldly information, the human brain generates self- and world models, by extracting statistical patterns of information from its embodied and worldly interactions (Conant & Ross Ashby, 1970). These generative models of the cause of incoming sensory inputs are based on Bayesian ‘prior’ beliefs² about the likely ‘hidden’ causes of the sensory information. These models form the basis of the so-called ‘expectations’ of the agent about the causal structure of its internal and external world (Rao and Ballard, 1999, Friston, 2005).

In a nutshell, our ongoing perceptions, cognition and actions are processed through the lens of prior self- and world-related information processing. If this is so, then it becomes crucial to look at how these perceptual inputs get off the ground from the outset.

In this paper we lay the theoretical basis for understanding how humans self-regulate their homeostatic bodily states and build their most basic self- and world-model, literally through others’ bodies, in utero. Specifically, we define in utero development as a process co-embodiment and co-homeostasis, and highlight their close relationship.

Indeed, one basic yet overlooked aspect of current PP and AIF approaches in both philosophy and cognitive neuroscience is that brains (and minds), and human bodies, first develop within another human body. The most basic perceptions and actions emerge already in utero (Young, 2005, Zoia et al., 2007, Castiello et al., 2010, Piontelli, 2010, Lymer, 2011, Ciaunica and Crucianelli, 2019, Quintero and De Jaegher, 2020). Crucially for our discussion here, while not all humans will have the experience of being pregnant or carrying a baby, the experience of being carried and growing within another person’s body is universal.³

Previous work looked at sensorimotor, homeostatic and bodily mechanisms operating already in early stages of development (Delafield-Butt and Gangopadhyay, 2013, Ciaunica, 2016, Ciaunica and Fotopoulou, 2017, Fotopoulou and Tsakiris, 2017, Atzil and Barrett, 2017). Here we focus on pregnancy, a case where two individuating organisms literally grasp/ grip one into each other. Specifically, we stress the idea that if we endorse a developmental bottom-up perspective, then embodiment should be examined through the lens of co-embodiment in humans. Contrary to the common view of the foetus being passively ‘contained’⁴ and solipsistically ‘trapped’ in the solitude of the womb, we will present evidence speaking in favour of an active and bidirectional co-regulation and constant negotiation between the two living bodies (Quintero & de Jaegher, 2020), what we will call ‘co-homeostasis’.

This paper proceeds as follows. We start in Section 2 by providing a minimal working definition of ‘embodiment’, before introducing the key notion of co-embodiment. The co-embodiment thesis will allow us to lay the preliminary ground for introducing the notion of homeostasis, allostasis and ‘co-homeostasis’, in Section 3, where we will propose an active inference reading of in utero development of perceptual experiences. We then show that the case of pregnancy offers a clear and fundamental example of co-embodiment, in Section 4, building upon theoretical and empirical work tackling the emergence of perceptual experiences in utero. Section 5 briefly discusses potential implications of endorsing a developmental perspective on current discussions regarding the nature of the human selfhood and conscious experiences. We conclude that when it comes to understanding the nature of our perceptual experiences and embodiment, the ‘infant is father to the human’ - to paraphrase Wordsworth.