The neural mechanisms underlying the aging-related enhancement of positive affects: electrophysiological evidences

The role of individual differences in emotional word recognition: Insights from a large-scale lexical decision study

This work presents a large lexical decision mega-study in Spanish, with 918 participants and 7500 words, focusing on emotional content and individual differences. The main objective was to investigate how emotional valence and arousal influence word recognition, controlling for a large number of confounding variables. In addition, as a unique contribution, the study examined the modulation of these effects by individual differences. Results indicated a significant effect of valence and arousal on lexical decision times, with an interaction between these variables. A linear effect of valence was observed, with slower recognition times for negative words and faster recognition times for positive words. In addition, arousal showed opposite effects in positive and negative words. Importantly, the effect of emotional variables was affected by personality traits (extroversion, conscientiousness and openness to experience), age and gender, challenging the 'one-size-fits-all' interpretation of emotional word processing. All data collected in the study is available to the research community: https://osf.io/cbtqy . This includes data from each participant (RTs, errors and individual differences scores), as well as values of concreteness (n = 1690), familiarity (n = 1693) and age of acquisition (n = 2171) of the words collected exclusively for this study. This is a useful resource for researchers interested not only in emotional word processing, but also in lexical processing in general and the influence of individual differences.

More organized white matter is associated with positivity bias in older adults

On average, healthy older adults prefer positive over neutral or negative stimuli. This positivity bias is related to memory and attention processes and is linked to the function and structure of several interconnected brain areas. However, the relationship between the positivity bias and white matter integrity remains elusive. The present study examines how white matter organization relates to the degree of the positivity bias among older adults. We collected imaging and behavioral data from 25 individuals (12 females, 13 males, and a mean age of 77.32). Based on a functional memory task, we calculated a Pos-Neg score, reflecting the memory for positively valenced information over negative information, and a Pos-Neu score, reflecting the memory for positively valenced information over neutral information. Diffusion-weighted magnetic resonance imaging data were processed using Tract-Based Spatial Statistics. We performed two non-parametric permutation tests to correlate whole brain white matter integrity and the Pos-Neg and Pos-Neu scores while controlling for age, sex, and years of education. We observed a statistically significant positive association between the Pos-Neu score and white matter integrity in multiple brain connections, mostly frontal. The results did not remain significant when including verbal episodic memory as an additional covariate. Our study indicates that the positivity bias in memory in older adults is associated with more organized white matter in the connections of the frontal brain. While these frontal areas are critical for memory and executive processes and have been related to pathological aging, more extensive studies are needed to fully understand their role in the positivity bias and the potential for therapeutic interventions.

Aging and distractor resistance in working memory: Does emotional valence matter?

Background

Emotional stimuli used as targets of working memory (WM) tasks can moderate age-related differences in WM performance, showing that aging is associated with reductions in negativity bias. This phenomenon is referred to as the positivity effect. However, there is little research on whether emotional distractors have a similar moderating effect. Moreover, the underlying neural mechanism of this effect has not been studied. In this study, we examined the behavioral and neurophysiological basis for age differences in resistance to emotional distractors within WM.

Methods

Older adults (n = 30, ages 60–74) and young adults (n = 35, ages 19–26) performed a 2-back task in which a digit was superimposed on a face with a happy, angry, or neutral expression as a distractor. Event-related potential (ERP) was simultaneously recorded to assess P2, N2, and later positive potential (LPP) amplitudes.

Results

Older adults were less accurate and slower than young adults on the WM task. Moreover, the results demonstrated a significant interaction between age and emotional valence on response accuracy, young adults' performance was worse when the distractor was neutral or positive than when it was negative, but there was no effect of the emotional valence of distractors on older adults’ WM performance. ERP analyses revealed greater P2 amplitude in older adults than young adults, regardless of the emotional valence of distractors. However, older adults and young adults did not differ on N2 or LPP amplitude, and negative distractors elicited greater N2 than positive distractors in both age groups.

Conclusions

The behavioral findings provided evidence of age-related reductions in negativity bias. Thus, the behavioral measures indicated a positivity effect in WM. However, the ERP results did not show this same interaction. These discrepant results raise questions about whether and to what extent older and young adults differ in controlling the effect of emotional distractors in WM.

Supplementary Information

The online version contains supplementary material available at 10.1186/s40359-022-00953-y.

An ERP investigation of age differences in the negativity bias for self-relevant and non-self-relevant stimuli

As we age, we show increased attention and memory for positive versus negative information, and a key event-related potential (ERP) marker of emotion processing, the late positive potential (LPP), is sensitive to these changes. In young adults the emotion effect on the LPP is also quite sensitive to the self-relevance of stimuli. Here we investigated whether the shift toward positive stimuli with age would be magnified by self-relevance. Participants read 2-sentence scenarios that were either self-relevant or non-self-relevant with a neutral, positive, or negative critical word in the second sentence. The LPP was largest for self-relevant negative information in young adults, with no significant effects of emotion for non-self-relevant scenarios. In contrast, older adults showed a smaller negativity bias, and the effect of emotion was not modulated by self-relevance. The 3-way interaction of age, emotion, and self-relevance suggests that the presence of self-relevant stimuli may reduce or inhibit effects of emotion for non-self-relevant stimuli on the LPP in young adults, but that older adults do not show this effect to the same extent.

Positivity effect in aging: evidence for the primacy of positive responses to emotional ambiguity

Older compared to younger adults show greater amygdala activity to positive emotions, and are more likely to interpret emotionally ambiguous stimuli (e.g., surprised faces) as positive. While some evidence suggests this positivity effect results from a top-down, effortful mechanism, others suggest it may emerge as the default or initial response. The amygdala is a key node in rapid, bottom-up processing and patterns of amygdala activity over time (e.g., habituation) can shed light on the mechanisms underlying the positivity effect. Younger and older adults passively viewed neutral and surprised faces in an MRI. Only in older adults, amygdala habituation was associated with the tendency to interpret surprised faces as positive or negative (valence bias), where a more positive bias was associated with greater habituation. Interestingly, although a positive bias in younger adults was associated with slower responses, consistent with an initial negativity hypothesis in younger adults, older adults showed faster categorizations of positivity. Together, we propose that there may be a switch to a primacy of positivity in aging.

The effect of emotional valence and age of faces on adults and children's inattentional blindness

Inattentional blindness (IB) refers to the nature of an individual being unaware of an unexpected stimulus when focusing on an attentional task. Investigation into IB provides an innovative approach for the research of attentional bias that is connected with an individual's immediate attentional capture. This study explored the effect of emotional valence and age of faces on the IB rates of children and adults. We employed a between-subject experimental design with a 2 (age of participants: child, adult) × 2 (age of face: child face, adult face) × 2 (emotional valence: positive, negative) method and used the classic IB task of cross judgment. The participants included 79 adults (54.63 ± 8.192 years old) and 78 children (10.62 ± 2.32 years old). The results showed that: (1) The IB rates of the two groups differed significantly. Children performed better than adults in detecting the faces appearing unexpectedly. (2) The effect of emotional valence only emerged on adult participants' IB. Adults were significantly more likely to detect the positive-emotional faces than the negative-emotional ones. (3) The age of a face was not a significant factor to predict participants' IB. Neither children nor adults showed a preference for the faces of a specific age (e.g., their own age). These findings revealed the distinct characteristics of attentional capture of children and adults when confronting unexpected facial stimuli.

Automatic Suppression Reduces Anxiety-Related Overestimation of Time Perception

Anxiety has been found to lengthen time perception, especially the time perception of negative stimuli. This anxiety-related time overestimation is thought to be mainly associated with massively increased arousal. Suppression, which can be achieved either deliberately or automatically, has been demonstrated to be effective in reducing arousal. Consequently, the present study explored the effectiveness of both deliberate suppression (Experiment 1) and automatic suppression (Experiment 2) in reducing the time distortion in anxiety. A temporal bisection task (TBT), featuring negative and neutral pictures, was used to measure time perception, while the self-reported arousal was used to assess arousal. The deliberate suppression was manipulated by asking participants to suppress their emotional expressions; while automatic suppression was manipulated through a sentence-unscrambling task featuring suppression-related words, which can unconsciously prime suppression. The results of Experiment 1 showed that deliberate suppression did not reduce the anxiety-related time overestimation and arousal. However, Experiment 2 showed that automatic suppression significantly reduced the anxiety-related time overestimation, with significant arousal reduction being observed. In conclusion, automatic suppression, but not deliberate suppression, is effective for reducing the effect of anxiety on time perception.

Gender Role, But Not Sex, Shapes Humans' Susceptibility to Emotion

It is unknown whether the famous sex-related difference in emotion processing is accounted for by biological sex, gender role, or their interaction. To clarify the issue, in Study 1 we recorded event-related potentials in response to negative and positive images of diverse intensities when 47 masculine (26 males) and 47 feminine (22 males) subjects performed a non-emotional task. The occipital P1 and N1 amplitudes were larger in women than in men, while feminine subjects showed larger N1 amplitudes than masculine subjects, regardless of sex. Moreover, feminine subjects showed enhanced frontocentral N2 (210-270 ms) amplitudes for highly and mildly negative than for neutral stimuli, while masculine subjects showed an emotion effect only for highly negative stimuli. The feminine-specific effect for mildly negative stimuli was positively correlated to the feminine score, and this correlation was located to the anterior cingulate and the superior and medial frontal gyri. Furthermore, feminine but not masculine subjects showed enhanced parietal P3 (330-560 ms) amplitudes for highly and mildly positive than for neutral stimuli, an effect positively related to the feminine score and localized to the precuneus, posterior cingulate, and superior temporal gyrus. Machine learning analyses verified that single-trial N2 and P3 amplitudes of feminine subjects reliably discriminated the intensity of negative and positive stimuli, respectively. For ecological considerations, in Study 2 we used an observational approach (n = 300) and confirmed that feminine gender role, rather than biological sex, predicted individual differences in daily experience of emotion-related psychopathological symptoms. These findings provide solid evidence for the critical impact of gender role rather than sex on emotional susceptibility.

The Childhood Maltreatment Modulates the Impact of Negative Emotional Stimuli on Conflict Resolution

It has been reported that negative emotional stimuli could facilitate conflict resolution. However, it remains unclear about whether and how the impact of negative emotional stimuli on conflict resolution varies depending on childhood maltreatment. To clarify this issue, seventy-nine subjects were required to perform an arrow Eriksen Flanker Task which was presented in the center of emotional pictures. The present study found a significant interaction effect of childhood maltreatment and emotion on executive attention scores in reaction times (RTs) that reflect conflict resolution speed. For subjects in high childhood maltreatment, negative pictures elicited smaller executive attention scores in RTs than neutral and positive pictures, while neutral and positive pictures elicited similar executive attention scores in RTs. By contrast, for subjects in low childhood maltreatment, executive attention scores in RTs were similar across three conditions. These results suggest that the speed of conflict resolution is enhanced in high, instead of low, childhood maltreatment in situations of negative stimuli. This finding extends our understanding of the interaction among emotion, childhood maltreatment and conflict resolution.

The Role of Emotion Regulation in Reducing Emotional Distortions of Duration Perception

Emotional events, especially negative ones, are consistently reported to last longer than neutral events. Previous studies suggested that this distortion of duration perception is linked to arousal and attention bias in response to emotional events. Reappraisal and suppression, arguably the most effective strategies for emotion regulation, have been demonstrated to decrease such arousal and attention bias. The present study investigated whether reappraisal and suppression can reduce emotional distortions of duration perception. Seventy-eight Chinese undergraduates were recruited as paid participants and randomly assigned to nonregulation, reappraisal, and suppression groups. Before they performed a temporal bisection task involving presentation of emotional pictures for different durations, the groups were each given one of three different sets of instructions requiring them to passively perceive, reappraise, or suppress the emotions of the pictures. The results indicated that the distortion of duration perception occurred only in the nonregulation group, suggesting that it can be effectively reduced by reappraisal and suppression.