The Episodic Prototypes Model (EPM): On the nature and genesis of facial representations.

Tobias Matthias Schneider,Claus-Christian Carbon

doi:10.1177/20416695211054105

Abstract

Faces undergo massive changes over time and life events. We need a mental representation which is flexible enough to cope with the existing visual varieties, but which is also stable enough to be the basis for valid recognition. Two main theoretical frameworks exist to describe facial representations: prototype models assuming one central item comprising all visual experiences of a face, and exemplar models assuming single representations of each visual experience of a face. We introduce a much more ecological valid model dealing with episodic prototypes (the Episodic Prototypes Model—EPM), where faces are represented by a low number of prototypes that refer to specific Episodes of Life (EoL, e.g., early adulthood, mature age) during which the facial appearance shows only moderate variation. Such an episodic view of mental representation allows for efficient storage, as the number of needed prototypes is relatively low, and it allows for the needed variation within a prototype that keeps the everyday and steadily ongoing changes across a certain period of time. Studies 1–3 provide evidence that facial representations are highly dependent on temporal aspects which is in accord with EoL, and that individual learning history generates the structure and content of respective prototypes. In Study 4, we used implicit measures (RT) in a face verification task to investigate the postulated power of the EPM. We could demonstrate that episodic prototypes clearly outperformed visual depictions of exhaustive prototypes, supporting the general idea of our approach.

Highlights

Face researchers mainly concentrate on the perception of faces and how we can recognize them
Our results suggest that facial development across about 60 years is optimally divided into approximately four clustered episodes, whereas baby faces constitute their own episode of facial representations next to a “youngster episode”, a “middle-age episode”
The revealed pattern for younger relatives who could have experienced the respective face for only a few years was very similar to that of older relatives having had much more experience across decades. This points to a universal mechanism where the episodic prototype containing more recent outward appearances, those which are most important for recognizing people in everyday life contexts, is primarily activated and referred to when we think of the prototypical outward appearance of a target person

Summary

Introduction

Face researchers mainly concentrate on the perception of faces and how we can recognize them (see, e.g., Akselrod-Ballin & Ullman, 2008; Burton et al, 2005; Carbon, 2011; Gao & Wilson, 2014; Jenkins & Burton, 2008; Mileva et al, 2020; Patterson & Baddeley, 1977; Schneider & Carbon, 2017b). Population-level face-spaces (referring to face-spaces across different identities) (e.g., Busey, 1998; Valentine and Endo, 1992). Individual-level face-spaces: given a certain familiar facial identity, the respective prototype (most typical face) provides the centroid of this face-space, whereas less typical exemplars of the identity are less densely clustered in the periphery (we will refer to this interpretation for the present study). All unique exemplars of a face are encoded as points in this n-dimensional space along face-discriminating dimensions such as facial expression, age, etc. It is assumed that this face-space corresponds to one’s facial representation of this particular identity in the associative network (see e.g., Benson and Perrett, 1993; Busey, 1998; Reinitz et al, 1992; Webster et al, 2004; Webster & MacLeod, 2011)

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