Emotional reactions are organized by underlying motivational states-defensive and appetitive-that have evolved to promote the survival of individuals and species. Affective responses were measured while participants viewed pictures with varied emotional and neutral content. Consistent with the motivational hypothesis, reports of the strongest emotional arousal, largest skin conductance responses, most pronounced cardiac deceleration, and greatest modulation of the startle reflex occurred when participants viewed pictures depicting threat, violent death, and erotica. Moreover, reflex modulation and conductance change varied with arousal, whereas facial patterns were content specific. The findings suggest that affective responses serve different functions-mobilization for action, attention, and social communication-and reflect the motivational system that is engaged, its intensity of activation, and the specific emotional context.

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Adhering to the view that emotional reactivity is organized in part by underlying motivational states-defensive and appetitive-we investigated sex differences in motivational activation. Men's and women's affective reactions were measured while participants viewed pictures with varied emotional and neutral content. As expected, highly arousing contents of threat, mutilation, and erotica prompted the largest affective reactions in both men and women. Nonetheless, women showed a broad disposition to respond with greater defensive reactivity to aversive pictures, regardless of specific content, whereas increased appetitive activation was apparent for men only when viewing erotica. Biological and sociocultural factors in shaping sex differences in emotional reactivity are considered as possible mediators of sex differences in emotional response.

Visual attention can be voluntarily directed toward stimuli and is attracted by stimuli that are emotionally significant. The present study explored the case when both processes coincide and attention is directed to emotional stimuli. Participants viewed a rapid and continuous stream of high-arousing erotica and mutilation stimuli as well as low-arousing control images. Each of the three stimulus categories served in separate runs as target or nontarget category. Event-related brain potential measures revealed that the interaction of attention and emotion varied for specific processing stages. The effects of attention and emotional significance operated additively during perceptual encoding indexed by negative-going potentials over posterior regions (ϳ200 -350 ms after stimulus onset). In contrast, thought to reflect the process of stimulus evaluation, P3 target effects (ϳ400 -600 ms after stimulus onset) were markedly augmented when erotica and mutilation compared with control stimuli were the focus of attention. Thus, emotion potentiated attention effects specifically during later stages of processing. These findings suggest to specify the interaction of attention and emotion in distinct processing stages.

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A repetition paradigm was used to assess the nature of affective modulation of early and late components of the event-related potential (ERP) during picture viewing. High-density ERPs were measured while participants passively viewed affective or neutral pictures that were repeated up to 90 times each. Both ERP components were modulated by emotional arousal, with ERPs elicited when viewing pleasant and unpleasant pictures different than when viewing neutral pictures. On the other hand, repetition had different effects on these two components. The early occipitotemporal component (150-300 msec) primarily showed a decrease in amplitude within a block of repetitions that did not differ as a function of picture content. The late centroparietal component (300-600 msec) showed a decrease both between and within blocks of repetitions, with neutral pictures eliciting no late positive potential in the final block of the study. The data suggest that the early ERP primarily reflects obligatory perceptual processing that is facilitated by active short-term memory representations, whereas the late ERP reflects increased resource allocation due to the motivational relevance of affective cues.

Modulation of the startle reflex by sensory, attentional, and emotional processes was explored by presenting acoustic startle probes at various delays following picture onset. Within 500 ms of onset, blinks were first greatly facilitated and then inhibited, indicating prepulse facilitation and prepulse inhibition that did not vary with affect. Attention allocation to the picture continued across the viewing interval and was most pronounced for emotional pictures, as determined by attenuation of the P3 component to the startle probe. Startle potentiation for unpleasant pictures occurred later in the viewing interval and was strongest for highly arousing pictures. Taken together, the startle reflex during picture viewing is modulated by sequential and sometimes concurrent processes of prepulse facilitation, prepulse inhibition, attentional inhibition, and affective modulation, with reflex magnitude reflecting the net effect of multiple processes.

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