Date of Award

5-2026

Document Type

Thesis

Degree Name

Master of Arts in Psychological Science

Department

Psychology

First Reader/Committee Chair

Brunet, Nicolas

Abstract

The N170 component plays a key role in face perception, but how attention influences it remains debated. In a series of five electroencephalography (EEG) experiments, we examined how attention to different facial features (holistic versus feature-based) affects the N170 amplitude. This study aims to determine whether perceptual competition explains these effects. In a preliminary study (Experiment 1), participants were primed to focus on either gender, age, emotional expression, race, or no specific task. This study showed a larger amplitude for gender and age, followed by emotion, with minimal differences for race, and no task was assigned. Since all these conditions involved holistic processing, we can conclude that the N170 is sensitive to facial perception as a whole. To further explore these findings, Experiment 2 investigated attentional differences in the N170 during both holistic and feature-based processing. Participants viewed faces with a small number and were primed on either the number or the emotional expression. The study revealed surprising results: a larger N170 amplitude when focusing on the number. Follow-up studies examined how attention affects N170 amplitude across different tasks. Experiment 3 employed a more complex design, focusing on two numbers in the stimuli (one inside the face and one outside the face), along with emotional expression and eye color. Unlike the previous study, a larger N170 was elicited when attending to emotion, with the smallest response associated with eye color. Although these results were expected, it was still surprising that the smallest amplitude was for eye color, given the numbers. To better understand these unexpected results, two additional studies were conducted. Experiment 4 examined differences in amplitude when focusing on emotion and eye color, while Experiment 5 investigated emotion and numbers placed either inside or outside the face (one inside, one outside, or both). The surprising increase in the N170 observed in previous studies may suggest attentional competition within the face area, leading to increased face-related neural responses even when attention is not specifically directed toward the face. Different types of attention clearly affect the N170 response, which is associated with activity in the fusiform face area (FFA). Holistic face processing that requires attention (such as age, gender, or emotion) produces larger N170 amplitudes than feature-based attention (such as skin or eye color), indicating that face recognition mainly functions at the integrated, whole-face level. Overall, these findings highlight the dynamic relationship between task demands and face perception, providing new insights into how attention influences early visual processing.

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