Christmas is a time of joy, celebration and love for many across the world. However, these feelings are not universally shared, and like a festive Marmite others find the obligatory decorations, mulled wine and mince pies a bit of a humbug! So, what might lead to such different opinions? We can perhaps provide an explanation based upon learned experiences that change how much we like and want something.

There are some things that we innately like or dislike. Examples are sweet and bitter tastes, to which we have clearly divergent responses from very early on in life. However, tastes can and do change. There is no in-born knowledge of Christmas and whether we like it or not must come from our experiences.

We acquire learned responses to other stimuli as well, such as our favourite TV shows, places and designer brands. This happens because our brains remember how we felt when we had contact with these stimuli. By pairing a stimulus with our feelings and emotions, the stimulus acquires an ‘incentive value’, which allows it to unconsciously influence our future emotions and behaviour. Over time we may no longer remember why something makes us feel the way it does, but the effect of the experience can endure.

Normally our brains’ incentive learning mechanisms help to keep us happy and healthy by guiding us to acquire good things and avoid harm. So for the many children who in this country have a positive experience of Christmas, incentive learning leads them to like the holiday season.

However, sentiments are more divided among adults. It is unlikely that those who have a dislike of Christmas have always held that view, so what could have led to these unfestive feelings? In the case of the infamous Ebenezer Scrooge, from Charles Dickens’s novella, ‘A Christmas Carol’, lonely childhood Christmases and an unloving father seem to have entrenched a negative incentive memory of Christmas. Over time this makes him bitter and hateful of Christmas time.
In the previous century, it was believed that memories were permanent records of our experiences and could not be changed once learned. However, modern science has since revealed that, like Mr Scrooge, it is never too late to change your ways. Memories can be altered or updated, and this may involve a process called ‘reconsolidation’.

Reconsolidation normally acts to maintain and update memories within the brain. This allows us to be adaptable, and make informed decisions using the most current information about a situation. However, sometimes this system can go wrong and allow excessively strong memories to drive maladaptive behaviour; such as in post-traumatic stress disorder, or addiction to alcohol or abuse of drugs.

Hopefully science can come to the rescue. Recent research has shown us how reconsolidation can be used experimentally to modify, or even erase a memory. Work is ongoing to harness these reconsolidation mechanisms to develop novel treatments for when memories in the brain go wrong. Weakening negative emotional memories may help combat phobias and post-traumatic stress, while combatting excessively strong positive incentive memories may help reduce rates of addiction and relapse.

For those with a deep seated loathing for the festive spectacle, or even an excessive liking for it, there is the possibility that one day soon modifying our memories will not require a visit from the Ghosts of Christmas Past, Present and Yet-to-Come. While modifying memories may become routine medically in the future, whether you enjoy Christmas or not, would you want to change its incentive value for you?

Dr Marc Exton-McGuinness, Research Fellow, School of Psychology, University of Birmingham

Dr Charlotte Flavell, Research Fellow, School of Psychology, University of Birmingham

Dr Jonathan Lee, Reader, School of Psychology, University of Birmingham