Early attachment relationships exert lasting effects on psychophysical health across the lifespan. Limited behavioral evidence suggests that these effects stem from how individuals perceive, interpret, and respond to their environment. This study investigated whether adults' attachment representations modulate autonomic responses to happy and sad facial expressions, evidenced by changes in pupil size. We utilized a sample of healthy adults (N = 100
68% females, 18-35 years, prevalently White European). In an eye-tracking experiment, we assessed pupil dilation to happy and sad facial expressions (n = 152 trials). Dismissing and preoccupied attachment orientations were assessed as continuous dimensions via self-report. Linear mixed models revealed that individuals with higher scores on dismissing orientations exhibited a significant increase in pupil dilation in response to sad and not happy expressions. No significant effects were observed for preoccupied orientations, age, or sex. These findings suggest that individuals with increased scores on dismissing attachment show heightened arousal to negative emotions.