Effect of positive emotion on consolidation of memory for faces: The modulation of facial valence and facial gender

Post-encoding positive emotion impairs associative memory for English vocabulary

There is evidence that emotion induced during encoding impairs associative memory (e.g., Bisby, Horner, Bush, & Burgess, 2018), yet the effect of post-encoding emotion (particularly positive emotion) on associative memory remains largely unclear. Two experiments were conducted to examine the effect of post-encoding positive emotion on associative memory for English vocabulary. In Experiment 1, high school students memorized Chinese definitions of a list of English words, immediately recalled the Chinese definitions, watched a neutral or comic video, and took a delayed memory test 25 minutes after encoding. The result showed a significant impairing effect of post-encoding positive emotion on memory for Chinese definitions. In Experiment 2, primary school students encoded English words with their associative pictures, took an immediate test where, on each trial, they were asked to choose the correct English word that matches a picture. Following the test, they watched a neutral or comic video, and took a memory test 10 minutes after encoding. Consistent with Experiment 1, Experiment 2 showed an impairing effect of positive emotion. Taken together, these findings support the hypothesis that post-encoding positive emotion can impair associative memory, providing important implications for acquisition of vocabulary of English as a foreign language.

Time-dependent effects of discrete post-encoding emotions on item memory and source memory

This study examined time-dependent effects of discrete emotions on item and source memory. In Experiment 1, after encoding, participants watched a comic, disgust-inducing, anger-inducing or neutral video at different delays. Positive emotion did not affect item memory but enhanced source memory (only in the 5 min delay). Anger impaired recognition in all delays, but a trend occurred for anger to impair source memory only in the 50 min delay. Disgust did not affect item memory, but a trend emerged for it to enhance and impair source memory in the 5 and 35 min delays, respectively. Experiment 2 showed that positive emotion and disgust had no effect on recognition, and consistent with Experiment 1, positive emotion, not anger or disgust, enhanced source memory. A trend occurred for positive emotion and disgust to impair source memory in the 0 min delay but not in the other delays. Consistent with Experiment 1, Experiment 3 showed that anger impaired both recognition and source memory (for males). Taken together, these findings suggest that the effect of emotion does vary depending on nature of memory tasks, category of emotion, and delay in emotion elicitation.

Memory for faces and voices varies as a function of sex and expressed emotion

We investigated how memory for faces and voices (presented separately and in combination) varies as a function of sex and emotional expression (anger, disgust, fear, happiness, sadness, and neutral). At encoding, participants judged the expressed emotion of items in forced-choice tasks, followed by incidental Remember/Know recognition tasks. Results from 600 participants showed that accuracy (hits minus false alarms) was consistently higher for neutral compared to emotional items, whereas accuracy for specific emotions varied across the presentation modalities (i.e., faces, voices, and face-voice combinations). For the subjective sense of recollection (“remember” hits), neutral items received the highest hit rates only for faces, whereas for voices and face-voice combinations anger and fear expressions instead received the highest recollection rates. We also observed better accuracy for items by female expressers, and own-sex bias where female participants displayed memory advantage for female faces and face-voice combinations. Results further suggest that own-sex bias can be explained by recollection, rather than familiarity, rates. Overall, results show that memory for faces and voices may be influenced by the expressions that they carry, as well as by the sex of both items and participants. Emotion expressions may also enhance the subjective sense of recollection without enhancing memory accuracy.

The adaptive value associated with expressing and perceiving angry-male and happy-female faces

Facial expressions are valuable for conveying and understanding the inner thoughts and feelings of the expressor. However, the adaptive value associated with a specific expression on a male face is different from a female face. The present review uses a functional-evolutionary analysis to elucidate the evolutionary advantage in the expression and perception of angry-male and happy-female faces over angry-female and happy-male faces. For the expressors, it is more advantageous for men to show angry facial expression as it signals dominance, averts aggression and deters mate poaching; it is more advantageous for women to display happy facial expression as it signals their willingness for childcare, tending and befriending. For the perceivers, those sensitive to angry men avoid being physically harmed while those sensitive to happy women gain social support. Extant evidence suggests that facial structure and cognitive mechanisms evolved to express and perceive angry-male and happy-female faces more efficiently compared to angry-female and happy-male faces.

Negative emotion elicited in high school students enhances consolidation of item memory, but not source memory

The study examined the effect of negative emotion on consolidation of both item and source memory. Participants learned words read by either a male or female. Then they watched either a negative or a neutral video clip. Memory tests were carried out either 25min or 24h after learning. The study yielded the following findings. First, negative emotion enhanced consolidation of item memory as measured by recognition memory in the 25-min delay, and enhanced consolidation of item memory as measured by free recall in both the 25-min and the 24-h delay. Second, negative emotion had little effect on consolidation of source memory, either in the 25-min or the 24-h delay. These findings provide evidence for the differential effects of negative emotion on item memory and source memory and have implications for using emotion as a strategy to intervene memory consolidation.