Interactions of Emotion and Self-reference in Source Memory: An ERP Study

The ownership memory self-reference effect shifts recognition criterion but not recognition sensitivity

Information referenced to the self is retrieved more accurately than information referenced to others, known as the memory self-reference effect. It is unclear, however, whether social context (identity of the other) or task factors alter decision-making processes. In a virtual object allocation task, female participants sorted objects into their own or another's (stranger or mother) basket based on a colour cue. Subsequently, they performed a recognition memory task in which they first indicated whether each object was old or new, and then whether it had been allocated to themselves or to the other. We obtained owner-specific hit rates and false-alarm rates and applied signal detection theory to derive separate recognition sensitivity (d') and recognition criterion parameters (c) for self- and other-owned objects. While there was no clear evidence of a recognition self-reference effect, or a change in sensitivity, participants adopted a more conservative recognition criterion for self- compared with other-owned objects, and particularly when the other-referent was the participant's mother compared with the stranger. Moreover, when discriminating whether the originally presented objects were self- or other-owned, participants were biased toward ascribing ownership to the 'other'. We speculate that these findings reflect ownership-based changes in decisional processing during the recognition memory self-reference paradigm.

The neural representation of self, close, and famous others: An electrophysiological investigation on the social brain

It is well established that the Self has a unique representation in the social brain, as evident from the Self-Referential Effect (SRE). However, the timing and neural mechanisms underlying the representation of individuals with varying degrees of closeness and emotional relevance to the Self remain unclear. Twenty-two participants read 260 personality traits and decided whether they described themselves, a close friend, or an admired celebrity. A strong Self-Referential Effect (SRE) was found at behavioral, ERP, and neuroimaging levels. Three anterior ERP components were identified as sensitive to social information: a P200 (250-350 ms) responding to famous others' traits, a P600 (500-700 ms) responding to self-trait processing, and a late positivity (800-950 ms) responding to self-trait processing and close traits. Source reconstructions revealed partially overlapping but distinct neural sources for each individual. The right precuneus (bodily self) and inferior frontal areas (inner voice) were active only during self-processing, while the right medial prefrontal cortex (BA10) was consistently active across tasks, showing a robust SRE. These findings provide insights into the neural mechanisms underlying the representation of the Self in social contexts.

Emotional autobiographical memory retrieval in time domain

Autobiographical memory (AM) is an important psychological phenomenon that has significance for self-development and mental health. The psychological mechanisms of emotional AM retrieval and their association with individual emotional symptoms remain largely unclear in the literature. For this purpose, the current study provided cue words to elicit emotional AMs. Event-related potentials (ERPs) associated with the retrieval process of AMs were recorded and analyzed. We found that the ERP component N400 was sensitive to both emotional valence and retrieval state, such that its amplitude was larger for negative compared to positive AMs, and larger responses for unrecalled compared to recalled AMs. Further, the N400 amplitude in the positive recalled condition was correlated with individual difference in depression (measured by the Beck Depression Inventory). Another ERP component, the late positive potential (LPP), was also sensitive to emotional valence, such that its amplitude was larger (i.e., more positive-going) for positive compared to negative cues. No significant effect was observed on the early ERP components P1, N1, or P2. The current findings bring new understanding on the difference between positive and negative AMs retrieval in the time domain. Also, the importance of this difference to the individual level of depression is worth noting.

Neuronal and behavioral affective perceptions of human and naturalness-reduced emotional prosodies

Artificial voices are nowadays embedded into our daily lives with latest neural voices approaching human voice consistency (naturalness). Nevertheless, behavioral, and neuronal correlates of the perception of less naturalistic emotional prosodies are still misunderstood. In this study, we explored the acoustic tendencies that define naturalness from human to synthesized voices. Then, we created naturalness-reduced emotional utterances by acoustic editions of human voices. Finally, we used Event-Related Potentials (ERP) to assess the time dynamics of emotional integration when listening to both human and synthesized voices in a healthy adult sample. Additionally, listeners rated their perceptions for valence, arousal, discrete emotions, naturalness, and intelligibility. Synthesized voices were characterized by less lexical stress (i.e., reduced difference between stressed and unstressed syllables within words) as regards duration and median pitch modulations. Besides, spectral content was attenuated toward lower F2 and F3 frequencies and lower intensities for harmonics 1 and 4. Both psychometric and neuronal correlates were sensitive to naturalness reduction. (1) Naturalness and intelligibility ratings dropped with emotional utterances synthetization, (2) Discrete emotion recognition was impaired as naturalness declined, consistent with P200 and Late Positive Potentials (LPP) being less sensitive to emotional differentiation at lower naturalness, and (3) Relative P200 and LPP amplitudes between prosodies were modulated by synthetization. Nevertheless, (4) Valence and arousal perceptions were preserved at lower naturalness, (5) Valence (arousal) ratings correlated negatively (positively) with Higuchi’s fractal dimension extracted on neuronal data under all naturalness perturbations, (6) Inter-Trial Phase Coherence (ITPC) and standard deviation measurements revealed high inter-individual heterogeneity for emotion perception that is still preserved as naturalness reduces. Notably, partial between-participant synchrony (low ITPC), along with high amplitude dispersion on ERPs at both early and late stages emphasized miscellaneous emotional responses among subjects. In this study, we highlighted for the first time both behavioral and neuronal basis of emotional perception under acoustic naturalness alterations. Partial dependencies between ecological relevance and emotion understanding outlined the modulation but not the annihilation of emotional integration by synthetization.

The Prominence of Self-referential Processing across ERP and Memory Consolidation in Children

We examined behavioral and electrophysiological indices of self-referential and valence processing during a Self-Referential Encoding Task in 9- to 12-year-old children, followed by surprise memory tasks for self- and other-referential trait adjectives. Participants endorsed more positive than negative self-referential information but equally endorsed positive and negative information about the other character. Children demonstrated enhanced parietal LPP amplitudes in response to self- compared to other-referential trait adjectives. Positive and negative information was differentially remembered depending on the order of the referent cues presented, suggesting that social information undergoes differential consolidation processes depending on the referent and the order of presentation.