Emotive content and sleep enhance memory for metaphorical language

Abstract Memory for emotional information is greater than for non-emotional information and is enhanced by sleep-related consolidation. Previous studies have focused on emotional arousal and valence of established stimuli, but what is the effect of sleep on newly acquired emotional information? Figurative expressions, which are pervasive in everyday communication, are often rated as higher in emotionality than their literal counterparts, but the effect of emotionality on the learning of metaphors, and the effect of sleep on newly acquired emotionally negative, positive and neutral language, is as yet poorly understood. In this study, participants were asked to memorise conventional (e.g. ‘ sunny disposition’ ) and novel (e.g. ‘ cloudy disposition’ ) metaphorical word pairs varying in valence, accompanied by their definitions. After a 12-hour period of sleep or wake, participants were tested on their recognition of word pairs and recall of definitions. We found higher arousal ratings were related to increased recognition and recall performance. Furthermore, sleep increased the accurate recognition of all word pairs compared to wake but also reduced the valence of word pairs. The results indicate better memory for newly acquired emotional stimuli, a benefit of sleep for memory, but also a reduction in emotional arousal as a consequence of sleep consolidation.