What Is the Effect of Basic Emotions on Directed Forgetting? Investigating the Role of Basic Emotions in Memory

Abstract

Studies presenting memory-facilitating effect of emotions typically focused on affective dimensions of arousal and valence. Little is known, however, about the extent to which stimulus-driven basic emotions could have distinct effects on memory. In the present paper we sought to examine the modulatory effect of disgust, fear, and sadness on intentional remembering and forgetting using widely used item-method directed forgetting (DF) paradigm. Eighteen women underwent fMRI scanning during encoding phase in which they were asked either to remember (R) or to forget (F) pictures. In the test phase all previously used stimuli were re-presented together with the same number of new pictures and participants had to categorize them as old or new, irrespective of the F/R instruction. On the behavioral level we found a typical DF effect, i.e., higher recognition rates for to-be-remembered (TBR) items than to-be-forgotten (TBF) ones for both neutral and emotional categories. Emotional stimuli had higher recognition rate than neutral ones, while among emotional those eliciting disgust produced highest recognition, but at the same time induced more false alarms. Therefore, when false alarm corrected recognition was examined the DF effect was equally strong irrespective of emotion. Additionally, even though subjects rated disgusting pictures as more arousing and negative than other picture categories, logistic regression on the item level showed that the effect of disgust on recognition memory was stronger than the effect of arousal or valence. On the neural level, ROI analyses (with valence and arousal covariates) revealed that correctly recognized disgusting stimuli evoked the highest activity in the left amygdala compared to all other categories. This structure was also more activated for remembered vs. forgotten stimuli, but only in case of disgust or fear eliciting pictures. Our findings, despite several limitations, suggest that disgust have a special salience in memory relative to other negative emotions, which cannot be put down to differences in arousal or valence. The current results thereby support the suggestion that a purely dimensional model of emotional influences on cognition might not be adequate to account for observed effects.

Keywords: Nencki Affective Pictures System; directed forgetting; discrete emotions; disgust.

FIGURE 1

Exemplary stimuli used in the current study eliciting disgust, fear, and sadness together with a neutral item. Note that the exemplary stimuli are only from Animals category and are not extreme for each emotion. Numbers represent order of the stimuli in the NAPS database.

FIGURE 2

False alarm corrected recognition accuracy (Pr) and response bias (Br) for correctly recognized TBR and TBF images (TBR_R and TBF_R, respectively). Error bars represent standard deviation. ^∗p < 0.05; ^∗∗p < 0.01; ^∗∗∗p < 0.001.

FIGURE 3

Directed forgetting effect on false alarm recognition accuracy [Pr (TBR) – Pr(TBF)] was significant for each emotional category and no interaction between basic emotion and stimulus type was revealed.

FIGURE 4

Subjective ratings for four types of stimuli used in the study. Error bars represent standard deviation. For the purpose of enhancing visibility of differences we used a scale going from 0 to 7.

FIGURE 5

The effect of intentional remembering and intentional forgetting in the whole brain analysis.

FIGURE 6

Contrast estimates extracted for each condition from five regions of interest.