Previous event-related potential (ERP) and brain imaging studies have suggested observer responses to others' pain are modulated by various bottom-up and top-down factors, including emotional primes. However, the temporal dynamics underlying the impact of emotional primes on responses to others' pain remains poorly understood. In the present study, we explored effects of negative, neutral, and positive emotional priming stimuli on behavioral and cortical responses to visual depictions of others in pain. ERPs were recorded from 20 healthy adults, who were presented with painful and non-painful target pictures following observation of negative, neutral, and positive emotional priming pictures. ERP analyses revealed that relative to non-painful pictures, differential P3 amplitudes for painful pictures were larger followed by negative primes than either neutral or positive primes. There were no significant differential P3 amplitudes for painful pictures relative to non-painful pictures were found followed neutral and positive emotional primes. These results suggest that negative emotional primes strengthen observers' attention toward others' pain. These results support the threat value of pain hypothesis.

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In this experiment, sensitivity to female facial attractiveness was examined by comparing event-related potentials (ERPs) in response to attractive and unattractive female faces within a study-test paradigm. Fourteen heterosexual participants (age range 18-24 years, mean age 21.67 years) were required to judge 84 attractive and 84 unattractive face images as either "attractive" or "unattractive." They were then asked whether they had previously viewed each face in a recognition task in which 50% of the images were novel. Analyses indicated that attractive faces elicited more enhanced ERP amplitudes than did unattractive faces in judgment (N300 and P350-550 msec) and recognition (P160 and N250-400 msec and P400-700 msec) tasks on anterior locations. Moreover, longer reaction times and higher accuracy rate were observed in identifying attractive faces than unattractive faces. In sum, this research identified neural and behavioral bases related to cognitive preferences for judging and recognizing attractive female faces. Explanations for the results are that attractive female faces arouse more intense positive emotions in participants than do unattractive faces, and they also represent reproductive fitness and mating value from the evolutionary perspective.

While empathic responses of individuals with autism-spectrum disorder have been reported to be modulated by top-down attention, it remains unclear whether empathy for pain in typically developing individuals with autistic traits also involves such top-down modulation mechanisms. This study employed the autism-spectrum quotient (AQ) to quantify autistic traits in a group of 1,231 healthy adults. Two subset groups (High-AQ and Low-AQ groups) were randomly selected from the highest and lowest 10% AQ scores respectively. We explored whether participants in both groups would differ in their response to others’ pain when their attention was directed toward (A-P tasks) or away (A-N tasks) from pain cues in auditory and visual experimental modalities. Compared to Low-AQ individuals, High-AQ individuals exhibited more suppressed N1 and P2 amplitudes in response to painful vocal cues in auditory A-N tasks. This suggests suppressed attentional and emotional processes of empathy for pain when High-AQ individuals have their attention directed away from others’ pain cues. No significant difference was found between both groups in the auditory A-P task, nor in the visual A-P and A-N tasks. These results suggest that top-down attention modulation of cortical empathic responses to others’ vocal pain is influenced by autistic traits.

When considering the "beauty-is-good" stereotype, facial attractiveness should facilitate empathy for pain. On the other hand, having in mind the "threat value of pain" hypothesis, pain cues would be more salient, and thus, its processing would not suffer influence by facial attractiveness. The eventrelated potential (ERP) allows investigating if one of these theories could predict individuals' responses regarding the perception of pain or attractiveness in others' faces. We tracked 35 participants' reactions to pictures depicting more and less attractive faces displayed in a painful and non-painful condition. Each participant completed the following two tasks when presented the images of faces: (1) the Pain Judgment Task, in which participants should rate the pain levels, and (2) the Attractiveness Judgment Task, in which participants should rate the attractiveness. Results showed that participants exhibited differences rating more and less attractive faces in the non-painful pictures, but not in the painful pictures. These results were observed in P3 and LPC amplitudes in the Pain Judgment Task, as well as in N170 and P2 amplitudes in the Attractive Judgment Task. Our results suggested that both explicit and implicit empathic pain processing inhibited the processing of attractiveness perception. These findings supported the "threat value of pain" hypothesis. Besides, in the Attractive Judgment Task, the N170 and P2 amplitudes for more attractive painful pictures were larger than those for more attractive nonpainful pictures. In contrast, no significant difference was found between the amplitudes for painful and non-painful, less attractive pictures. Our findings suggest that explicit facial attractiveness processing for more attractive face images potentiates the implicit empathy for pain processing, therefore partly supporting the "beautiful-is-good" stereotype. Empathy refers to the ability to understand and share others' feelings 1. When individuals witness others' pain or injuries, they usually can identify the pain and relate to these experiences as if they were their own 2. This competency is thus called empathy for pain 3,4. According to the "threat value of pain" hypothesis 5-8 , the perception of another's pain activates the individual's survival mechanisms, meaning that, they may experience withdrawal and avoidance like when exposed to real or perceived danger. Therefore, the ability to recognize others' pain helps individuals to avoid possible hazards and promotes empathic behavior 9. Physical attractiveness, as a symbol of biological quality signaling fertility and health 10,11 , plays an important role in interpersonal interactions in daily life. Attractive faces can be considered rewarding stimuli, eliciting positive emotional reactions. Those activate brain areas associated with the processing of positive emotions and rewarding, such as the nucleus accumbens and the ventral tegmental area 12. According to the "beauty-is-good" stereotype 13 , people with higher physical attractiveness are deemed b...