Year: 2015
Type: dissertation
Abstract: "The eyes are the windows to the soul." Cicero's quote captures how readily we use the eyes of facial expressions to communicate our internal states. However, we do not yet know how this ability came about. Darwin theorized that our emotional expressions evolved as functional adaptations for the expresser, which were then co-opted as social signals. Here, I set out to empirically bridge this gap in our understanding by showing how our facials expressions originated for sensory egocentric function, and how those origins were socially co-opted to serve expressions' contemporary allocentric function as signals of mental states. To do this, I focused on the eyes and their surrounding features, adopting Darwin's principles that the expressive features associated with the eyes' widening versus narrowing can be understood as opposing along a continuum of sensory regulation. For the expresser, I show how eye widening in fear versus eye narrowing in disgust expressions serve opposing sensory functions. Eye widening increased the visual field and light gathering to enhance visual sensitivity versus eye narrowing which increased light focusing to enhance visual acuity, adaptively serving fear's function in vigilance toward threat detection versus disgust's function in threat discrimination, respectively. For the expression's observer, eye widening enhanced the physical gaze signal to better transmit the direction of a mutual threat detected by fear. Further, the widening versus narrowing eye features that enhanced perceptual sensitivity versus discrimination similarly conveyed opposing mental states of information sensitivity versus discrimination. Together, the evidence connects the appearance of our expressions from their egocentric origins to their modern-day allocentric functions. Thus by the same eyes with which we see the world, we are provided windows not just into another's soul, but to a co-evolved history of how our individual survival was leveraged into a flourishing co-operative one.
Source: TSpace (University of Toronto)
Author: Daniel Hyuk-Joon Lee
Language: English
Subfield: Experimental and Cognitive Psychology
Field: Psychology
Domain: Social Sciences
Open Access status: green
OpenAlex ID: W2600288363