Are females more responsive to emotional stimuli? A neurophysiological study across arousal and valence dimensions

Abstract

Men and women seem to process emotions and react to them differently. Yet, few neurophysiological studies have systematically investigated gender differences in emotional processing. Here, we studied gender differences using Event Related Potentials (ERPs) and Skin Conductance Responses (SCR) recorded from participants who passively viewed emotional pictures selected from the International Affective Picture System (IAPS). The arousal and valence dimension of the stimuli were manipulated orthogonally. The peak amplitude and peak latency of ERP components and SCR were analyzed separately, and the scalp topographies of significant ERP differences were documented. Females responded with enhanced negative components (N100 and N200), in comparison to males, especially to the unpleasant visual stimuli, whereas both genders responded faster to high arousing or unpleasant stimuli. Scalp topographies revealed more pronounced gender differences on central and left hemisphere areas. Our results suggest a difference in the way emotional stimuli are processed by genders: unpleasant and high arousing stimuli evoke greater ERP amplitudes in women relatively to men. It also seems that unpleasant or high arousing stimuli are temporally prioritized during visual processing by both genders.

Fig. 1

Valence and arousal ratings of images used for males and females

Fig. 2

ERP components of a typical grand average waveform. Early components are marked with green and middle ones with red color. P100 usually is seen around 100 ms (maximum between 70 and 130 ms in our study), followed by N100 (minimum between 90 and 170 ms in our study), a peak with opposite polarity. P200 is obvious after 200 ms (maximum between 180 and 230 ms) followed by N200 (minimum between 200 and 300 ms) of opposite polarity. P300 is the next positive peak (between 300 and 400 ms) followed by the late positive potential (LPP), whose duration is from 400 to 900 ms

Fig. 3

Grand average ERPs of Fz, Cz, and Pz for males (left) and females (right). Arousal effects on the amplitude of P300 are evident; dashed lines are more positive than the solid ones. The regions in zoom show the valence effects on N200 amplitudes of Fz and Cz where unpleasant pictures (red lines) evoked more negative responses. The zoomed regions of electrode Pz also depict the valence effect on latency for males, since red lines (unpleasant) evoke faster N200 responses, as well as, the arousal effect on latency for females, since dashed lines (high arousal) evoke faster N200 responses

Fig. 4

Gender by arousal interaction is evident as the difference between high arousing (HA) and low arousing (LA) is greater in females than in males on N100 on Fz and Cz electrode

Fig. 5

Gender by valence interaction is evident as only females exhibited difference between pleasant and unpleasant stimuli on N100 on Pz electrode

Fig. 6

High arousing pictures elicited faster N200 responses than low arousing ones on Pz electrode on both males and females (F(1,26) = 5.1, P = 0.032)

Fig. 7

Unpleasant pictures elicited faster N200 responses than pleasant ones on Pz electrode on both males and females (F(1,26) = 5.82, P = 0.023)

Fig. 8

Topographies of ERP amplitude differences extracted from statistical analysis of all electrodes; F-values were calculated and plotted. F-values greater than 4 represent significant main effects of gender (a), arousal (b), and valence (c) across components. Gender effects on N100 and N200 amplitude are significant on central and left hemisphere electrodes