Keywords

Decision-Making, Human-Computer-Interaction, Trust, Salience, Anthropomorphism

Subject Categories

Cognitive Psychology | Computer Sciences

Abstract

As interactions with digital agents become increasingly integrated into daily life, understanding how visual representations influence social decision-making is critical. Previous research in human-computer interaction has frequently confounded the psychological effects of an agent's perceived human-likeness with the underlying visual salience of the stimuli. To address these persistent gaps, the present study systematically isolated the effects of human-likeness and visual cue trustworthiness on trust behavior while controlling for objective image properties. The present study expanded on and normed the Virtual Avatar Facial Stimuli Set (VAFSS), a comprehensive database comprising hundreds of identity-matched photographs and computer-generated avatars varying across a spectrum of human-likeness. Experiment 1 aimed to measure visual properties of the stimuli. To control for visual properties, image salience was objectively quantified through behavioral metrics (a dot-probe task) and computer vision models (OpenCV for bottom-up physical conspicuity and ResMem for top-down cognitive memorability). Utilizing these validated stimuli, subsequent experiments investigated the impact of facial trustworthiness and human-likeness on trust behavior using a Single-Shot Trust Game. Experiment 2 manipulated human-likeness along a morphing continuum, while Experiment 3 used a diverse, non-morphed set of naturalistic avatars rated post hoc for perceptions of human-likeness. Across both behavioral studies, results demonstrated a robust main effect of visual cue trustworthiness, where participants consistently invested more in trustworthy-looking agents. Crucially, human-likeness significantly moderated this behavior such that effect of facial trustworthiness on trust behavior was greater for highly human-like stimuli. Hierarchical linear mixed-effects modeling confirmed that this moderation persisted even after statistically controlling for both physical conspicuity and algorithmic memorability. These findings demonstrate that behavioral shifts in human-computer trust are not mere artifacts of an image's structural sharpness or memorability, but are driven by complex, top-down social evaluations inherently tied to the perceived "humanness" of the digital agent.

Completion Date

2026

Semester

Summer

Committee Chair

Nichole Lighthall

Degree

Doctor of Philosophy (Ph.D.)

College

College of Sciences

Department

Psychology

Format

PDF

Document Type

Dissertation

Language

English

Download

Share

COinS
 

Accessibility Statement

This item was created or digitized prior to April 24, 2027, or is a reproduction of legacy media created before that date. It is preserved in its original, unmodified state specifically for research, reference, or historical recordkeeping. In accordance with the ADA Title II Final Rule, the University Libraries provides accessible versions of archival materials upon request. To request an accommodation for this item, please submit an accessibility request form.