Recognition of emotional pictures: Behavioural and electrophysiological measures

Positive and negative touch differentially modulate metacognitive memory judgements for emotional stimuli

Touch plays a crucial role in providing humans with information from the external environment and can be perceived by humans as positively or negatively valenced. It is well documented that touch can differentially influence social functions, but very little is known about how touch can modulate (meta)cognition. Utilizing a within-subject design, participants were exposed to (a) positive, (b) negative, and (c) no touch, alongside encoding of emotionally valenced (positive and negative) images. After a 20-minute delay, participants completed a Yes/No recognition task to investigate how touch influenced memory-related decision components (e.g. criterion, confidence). Results showed that, compared to the control condition, both positive and negative touch were associated with overall lower confidence ratings, a less liberal response bias and slower response times. Interestingly, for correct recognitions, only negative touch (vs. no touch) led to inappropriately lower confidence and slower response times while both confidence and response time remained unaltered in positive touch. Our findings provide the first evidence that positive and negative touch differentially interact with metacognitive memory-related decisions. Altered metacognitive judgements after being touched could have significant consequences in applied settings, such as situations of eyewitness testimony.

Social cues tip the scales in emotional processing of complex pictures

Perception of a picture is influenced by the social information and emotional value it carries for the viewer. There are still many unanswered questions about how social and emotional processing are related, but it is clear they involve overlapping brain areas and are cognitively interconnected. Yet studies of emotion processing using standardized picture datasets typically leave the social content in the pictures free to vary. In a few studies where the social content has been measured, it correlated with emotional arousal and valence. Here we tested the association between social and emotional content orthogonally, by selecting a similar number of pictures in four categories varying in presence of nonverbal social cues (e.g., gestures, facial expression, body language) and emotional content (neutral, negative). Across two studies, participants (N = 698 in total) provided three ratings for each picture: social relevance (defined as the self-reported use of social cues to understand the picture), valence, and arousal. Despite our best effort to balance the presence of social cues between negative and neutral pictures, ratings of social relevance were strongly associated with ratings of arousal and, to a lesser extent, with valence. These findings likely reflect the intertwined nature of social and emotional processing, which has implications for the neurobiology underlying them, how these systems develop, and how picture databases are used in research.

Evaluating the Association of High Trait Anxiety With a Bias in Familiarity-Based Recognition of Emotional Stimuli

Abstract. In the past decades the role of cognitive biases as maintaining factors of anxiety has been widely researched. This theoretical framework assumes that vulnerability self-referential thoughts promote a hyper-vigilant mode of processing environmental stimuli. In this mode, threatening information increases attentional capture and therefore encoding and retrieval of such stimuli is enhanced. Although this attentional bias has been confirmed, the evidence concerning the memory bias is contradictory. Our hypothesis is that the bias in memory is expressed through the pattern of recognition. Particularly, the aim of this study was to evaluate the association of anxiety with familiarity, a deficient form of recognition which consists only in the identification of the item without retrieval of contextual information. Two groups of 17 participants with low and high anxiety levels performed an experimental task of visual recognition memory, using neutral, positive, and negative pictures. The experiment had two test phases, with a 24-hour interval, to evaluate possible effects of consolidation. The pattern of recognition was measured, behaviorally (through an independent Remember/Know paradigm) and through event-related potentials (ERP). Participants with higher levels of anxiety developed a bias in recognition of arousing stimuli (positive and negative) compared with the control group. This bias was observed behaviorally through an increase of familiarity-based recognition, and was associated with a positive modulation of a right parietal late positive component (LPC) at approximately 600 ms of latency. Participants with higher levels of anxiety are capable of recognizing arousing stimuli but lack efficiency in retrieving past contextual information compared to lower level anxiety participants. A recognition bias can be the first step in cognitive distortions that generate anxiety. This is, to our knowledge, the first study to explore the association of anxiety with familiarity-based recognition, using an independent Remember/Know paradigm combined with electrophysiological data. Further studies with bigger samples and more recording channels are needed to confirm the electrophysiological findings.

The effect of fearful expressions on recognition memory for faces: Behavioral and electrophysiological data

Facial expressions affect memory for face identity. We tested how fearful expressions modulate recognition memory for faces. In two studies, participants completed a continuous recognition task with fearful and neutral faces while their electroencephalogram was recorded. Each face stimulus was presented twice and participants were instructed to indicate whether it was presented for the first ('new') or second time ('old'). The false alarm rate was higher for fearful than neutral faces, which is opposite to the emotion enhancement effect on memory but in line with the liberal response bias for emotional information. There was no evidence of emotional modulation of the N400 old/new effect, which suggests that the sense of familiarity was not affected by fearful facial expressions. The LPC old/new effect, however, was modulated by facial expression, as it was absent for fearful faces because of a greater positivity in response to new fearful than new neutral faces. This LPC old/new effect finding may reflect that the emotional salience of fearful new faces is mistaken for a sense of recollection, resulting in an increased false alarm rate. In short, people seem more likely to (mistakenly) think that they have encountered a person before when the person looks scared compared to non-emotional, which has relevance for daily life and forensic situations such as police lineups.

The robustness of false memory for emotional pictures

Emotional material is commonly reported to be more accurately recognised; however, there is substantial evidence of increased false alarm rates (FAR) for emotional material and several reports of stronger influences on response bias than accuracy. This pattern is more frequently reported for words than pictures. Research on the mechanisms underlying bias differences has mostly focused on word lists under short retention intervals. This article presents four series of experiments examining recognition memory for emotional pictures while varying arousal and the control over the content of the pictures at two retention intervals, and one study measuring the relatedness of the series picture sets. Under the shorter retention interval, emotion increased false alarms and reduced accuracy. Under the longer retention interval emotion increased hit rates and FAR, resulting in reduced accuracy and/or bias. At both retention intervals, the pattern of valence effects differed based on the arousal associated with the picture sets. Emotional pictures were found to be more related than neutral pictures in each set; however, the influence of relatedness alone does not provide an adequate explanation for all emotional differences. The results demonstrate substantial emotional differences in picture recognition that vary based on valence, arousal and retention interval.

An exploratory high-density EEG investigation of the misinformation effect: Attentional and recollective differences between true and false perceptual memories

The misinformation effect, a phenomenon in which eyewitness memories are altered via exposure to post-event misinformation, is one of the most important paradigms used to investigate the reconstructive nature of human memory. The aim of this study was to use the misinformation effect paradigm to investigate differences in attentional and recollective processing between true and false event memories. Nineteen participants completed a variant of the misinformation paradigm in which recognition responses to true and misinformation based event details embedded within a narrative context, were investigated using high-density (256-channel) EEG with a 1-day delay between event exposure and test. Source monitoring responses were used to isolate event-related-potentials (ERPs) associated with perceptual (i.e. event) source attributions. Temporal-spatial analyses of these ERPs showed evidence of an elevated P3b and Late-Positive Component, associated with stronger context-matching responses and recollective activity respectively, in true perceptual memories relative to false misinformation based ones. These findings represent the first retrieval focused EEG investigation of the misinformation effect and highlight the interplay between attention and retrieval processes in episodic memory recognition.