Emotional events are more organized and distinctive than neutral events. We asked whether organization and distinctiveness can account for emotionally-enhanced memory. To examine organization, we compared memory for arousing, negatively-valenced pictures, and inter-related neutral pictures. To examine distinctiveness, we manipulated list composition, and compared mixed lists, which contained emotional and neutral items, to pure lists, which contained only items of a single type and removed the relative-distinctiveness advantage of emotional items. We show that emotional memory is enhanced in immediate memory tests as long as either organization or distinctiveness is allowed to play a role. When these effects are removed, in the comparison of emotional and related neutral items in pure lists, the emotional memory advantage is eliminated. Examining the contribution of mediating cognitive factors at a behavioral and neural level is crucial if we are to understand how emotion influences memory.

Memory for emotional events is usually very good even when tested shortly after study, before it is altered by the influence of emotional arousal on consolidation. Immediate emotion-enhanced memory may stem from the influence of emotion on cognitive processes at encoding and retrieval. Our goal was to test which cognitive factors are necessary and sufficient to account for EEM, with a specific focus on clarifying the contribution of attention to this effect. In two experiments, participants encoded negative-arousing and neutral pictures. In Experiment 1, under divided-attention conditions, negative pictures were better attended and recalled even when they were matched with neutral pictures on semantic relatedness and distinctiveness, and attention at encoding predicted subsequent emotion-enhanced memory. The memory advantage for emotional stimuli was only abolished when attention to emotional and neutral stimuli was also matched, under full-attention in Experiment 1 and under divided-attention in Experiment 2. Emotional memory enhancement was larger in Experiment 1 when the control of organization and distinctiveness was relaxed. These findings suggest that attention, organization and distinctiveness provide a necessary and sufficient account for immediate emotion-enhanced free recall memory.

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Background: Humans spontaneously mimic the facial expressions of others, facilitating social interaction. This mimicking behavior may be impaired in individuals with Parkinson's disease, for whom the loss of facial movements is a clinical feature.Objective: To assess the presence of facial mimicry in patients with Parkinson's disease.Method: Twenty-seven non-depressed patients with idiopathic Parkinson's disease and 28 age-matched controls had their facial muscles recorded with electromyography while they observed presentations of calm, happy, sad, angry, and fearful emotions.Results: Patients exhibited reduced amplitude and delayed onset in the zygomaticus major muscle region (smiling response) following happy presentations (patients M = 0.02, 95% confidence interval [CI] −0.15 to 0.18, controls M = 0.26, CI 0.14 to 0.37, ANOVA, effect size [ES] = 0.18, p < 0.001). Although patients exhibited activation of the corrugator supercilii and medial frontalis (frowning response) following sad and fearful presentations, the frontalis response to sad presentations was attenuated relative to controls (patients M = 0.05, CI −0.08 to 0.18, controls M = 0.21, CI 0.09 to 0.34, ANOVA, ES = 0.07, p = 0.017). The amplitude of patients' zygomaticus activity in response to positive emotions was found to be negatively correlated with response times for ratings of emotional identification, suggesting a motor-behavioral link (r = –0.45, p = 0.02, two-tailed).Conclusions: Patients showed decreased mimicry overall, mimicking other peoples' frowns to some extent, but presenting with profoundly weakened and delayed smiles. These findings open a new avenue of inquiry into the “masked face” syndrome of PD.

Previous studies demonstrate that perception of action presented audio-visually facilitates greater mirror neuron system (MNS) activity in humans (Kaplan and Iacoboni in Cogn Process 8(2):103-113, 2007) and non-human primates (Keysers et al. in Exp Brain Res 153(4):628-636, 2003) than perception of action presented unimodally. In the current study, we examined whether audio-visual facilitation of the MNS can be indexed using electroencephalography (EEG) measurement of the mu rhythm. The mu rhythm is an EEG oscillation with peaks at 10 and 20 Hz that is suppressed during the execution and perception of action and is speculated to reflect activity in the premotor and inferior parietal cortices as a result of MNS activation (Pineda in Behav Brain Funct 4(1):47, 2008). Participants observed experimental stimuli unimodally (visual-alone or audio-alone) or bimodally during randomized presentations of two hands ripping a sheet of paper, and a control video depicting a box moving up and down. Audio-visual perception of action stimuli led to greater event-related desynchrony (ERD) of the 8-13 Hz mu rhythm compared to unimodal perception of the same stimuli over the C3 electrode, as well as in a left central cluster when data were examined in source space. These results are consistent with Kaplan and Iacoboni's (in Cogn Process 8(2):103-113, 2007), findings that indicate audio-visual facilitation of the MNS; our left central cluster was localized approximately 13.89 mm away from the ventral premotor cluster identified in their fMRI study, suggesting that these clusters originate from similar sources. Consistency of results in electrode space and component space support the use of ICA as a valid source localization tool.