There is such a thing as an emotional hangover

The research published in the journal ‘Nature Neuroscience’ shows that such an emotional ‘hangover’ influences how we address and remember future experiences. It has been known for quite some time that emotional experiences (such as weddings, funerals, first kisses, historic events, childbirth or the death of a loved one) are better remembered than non-emotional ones, not only minutes after the event has occurred but even years later.

For example, more than 15 years on from the event, many people are still able to recall vividly where they were and what they were doing when they first heard about the terrible events that unfolded in the United States on 11 September 2001. However, this study also demonstrated that non-emotional experiences that followed emotional ones were also better remembered during a later memory test.

‘How we remember events is not just a consequence of the external world we experience, but is also strongly influenced by our internal states – and these internal states can persist and colour future experiences,’ explained Lila Davachi, an associate professor at New York University’s (NYU). ‘Emotion is a state of mind. These findings make clear that our cognition is highly influenced by preceding experiences and, specifically, that emotional brain states can persist for long periods of time.’

To obtain these findings, subjects were asked to view a series of scene images that contained emotional content and elicited arousal. Approximately 10 to 30 minutes later, one group then also viewed a series of non-emotional, ordinary scene images. Another group of subjects viewed the non-emotional scenes first followed by the emotional ones. Psychological arousal, measured in skin conductance, and brain activity, using fMRI, were monitored in both subject groups. Six hours later, both sets of subjects were administered a memory test of previously viewed images.

The researchers hypothesised that the carry-over effects of emotional experiences would manifest in low-frequency amygdala connectivity. Therefore, the researchers also examined whether this type of brain activity, present during emotional memory encoding, was also present during the neutral memory encoding phase in the two groups.

The results showed that the first group of subjects who were exposed to the emotion-invoking stimuli first had better long-term recall of the second set of more neutral images than the second group, who saw the emotional images second.

It was by looking at the fMRI results that unlocked the explanation for this – it seems that the brain states associated with emotional experiences carried over for 20 to 30 minutes and influenced how the subjects processed and remembered future experiences that were not emotional. In short, such a state as can be described as an ‘emotional hangover’ does indeed exist and can have long-lasting effects on the capacity of the brain’s ability to process and recall memories.

The EMOTIONAL MEMORY project is being carried out by the University of Geneva and is due to complete in February 2018. The study also received support from the US National Institute of Mental Health, the Swiss National Science Foundation and the German Research Foundation.

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