The influence of stress on emotional processing of pleasant stimuli: a psychophysiological investigation

Stress is known to alter emotional processing by selectively activating the defensive motivational system, biasing attention toward negative and threat-relevant stimuli. A well-established psychophysiological index of this modulation is the late positive potential (LPP), a centroparietal ERP component that indexes motivated attention toward emotional stimuli. While stress has been shown to increase the LPP for threatening content, considerably less is known about whether such effects extend to appetitive or neutral stimuli — leaving open the question of whether stress modulates emotional processing in a valence-general or valence-specific manner. The present study investigated whether distal and proximal stress modulate neural and subjective responses to pleasant and neutral images in a non-clinical sample of young adults. Emotional processing was assessed using the LPP and subjective affective ratings of valence and arousal. Neither distal nor proximal stress was significantly associated with LPP amplitude to pleasant stimuli, and subjective affective ratings did not differ as a function of stress levels. Mixed-model regression analyses confirmed that stress accounted for no significant variance in LPP activity. However, a significant negative association emerged between ACE scores and valence ratings for pleasant stimuli, indicating that individuals reporting greater childhood adversity perceived pleasant images as less pleasant. No other significant associations were observed. These findings suggest that childhood adversity may influence the subjective evaluation of pleasant images without affecting neural indices of motivated attention. More broadly, the results indicate that stress-related alterations in emotional processing may be selective for negative or threatening content, leaving electrocortical responses to pleasant stimuli largely intact.