WHAT do the Christmas holidays mean to you? Maybe it鈥檚 happy memories of long, lazy walks in the snow, excited children, crackling fires and the comforting smell of home cooking. Or maybe you鈥檙e the misery-guts in the corner grumbling about all the rubbish on telly, the naff music, inflated prices and packed shops. Why do some people have such a rosy picture of the festivities, while others share Ebenezer Scrooge鈥檚 view on life, even when their experiences might be near-identical? One word. Mood.
We all know that our mood affects how we see life. But did you realise that your mood affects far more than just the experiences of the moment? In fact, your mood during Christmas present will alter what you remember of Christmases past and could even distort your feelings and thoughts about Christmases in the future. 鈥淢ood is an internal state which filters external information,鈥� explains Klaus Fiedler, a psychologist from the University of Heidelberg in Germany. Importantly, it can even influence the way you learn, and how you think about things long after your state of mind has changed.
We are all familiar with the way places, smells or music we used to know well can bring memories flooding back. Mood can do the same. Edmund Rolls from the University of Oxford calls this context-dependent memory. When you form a new memory, he says, information about the context is also stored. It is linked to the main memory in a kind of network. When you try to remember, activity in any part of this network makes it easier to pull the target information off the memory shelf. Your mood is part of the context, says Rolls, so being in a good mood means you鈥檒l recall memories stored during previous good moods more easily.
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According to Fiedler, not only do you remember things you learned in the same state of mind more easily, you also recall more generally positive things when in a good mood, and more gloomy things when you鈥檙e feeling down. This selective memory has been demonstrated many times: psychologists use music, hypnosis or other techniques to alter someone鈥檚 mood, then ask them to recall events from the past. People who are feeling happy tend to remember more positive episodes and those who are feeling miserable tend to remember more negative ones. For the Scrooge-like among us, just being in a dejected state of mind means you鈥檒l remember unhappy times from your past, and the worst bits even from more joyful occasions.
But there鈥檚 even worse news for the non-festive. New findings suggest that feeling unseasonably wretched over the holidays not only dredges up past Christmas misery, it could also permanently sour future thoughts of the festivities. On the bright side, however, just one really fantastic Christmas might ensure that the sight of tinsel and fairy lights gives you a warm, cosy feeling forever.
Michael Rugg and his team from University College London looked at how the emotional context in which we learn something affects brain activity when we remember what was learned. In one study, for example, he asked people to read a series of emotionally laden sentences such as 鈥渢he farmer was shredded when he fell into the corn grinder鈥�. The volunteers were later shown emotionally neutral words such as 鈥渃orn鈥�, and asked to indicate whether or not they remembered seeing them in the sentences.
Surprisingly, correct recognition of the neutral words led to activity in core emotional regions of the brain. Other experiments along these lines have pointed to the same thing: if you learn neutral information in an emotionally charged context, remembering it triggers an emotional response. Rugg thinks this effect may be akin to the network idea 鈥� recalled words act as clues or contexts prompting people to dredge up their memories of the emotional sentences from storage, whether they want to or not.
The association between the emotional and the non-emotional could influence our everyday memories, suggests Rugg. It could also be part of the problem for people suffering from post-traumatic stress disorder who can鈥檛 help continually reliving emotionally distressing memories. 鈥淓motionally neutral cues in the environment somehow serve as reminders and cause these distressing memories to be retrieved,鈥� he explains.
There are other signs, too, that our mood or emotional state affects how we learn. In a recent study, Susanne Erk and Henrik Walter of the University of Ulm in Germany used a task similar to Rugg鈥檚, in which people were asked to learn words presented just after they had viewed emotionally charged images. The researchers found that when people learned words in a negative context, activity in a certain brain region that plays a vital role in emotions was a good predictor of how well they would later remember that information.
That brain region is called the amygdala 鈥� and Rugg found activity in exactly the same structure when people retrieved information learned in an emotional context. The fact that this emotion-related brain activity was so similar during learning and remembering strengthens the idea that recalling neutral information can evoke emotions very similar to those felt when it was learned.
Even more interestingly, Walter found that people remember neutral information better if they are in a good mood when they learn it. A sound lesson for anyone revising for exams 鈥� getting grumpy won鈥檛 help. The intriguing conclusion Walter draws is that state of mind really does alter the way information is coded into your memory. Any new information will be permanently stamped with your good or foul temper.
The whole picture looks very bleak for people who are chronically unhappy, like Scrooge. Erk and Walter鈥檚 work suggests they may learn less efficiently. Even worse, what they do learn and recall can add to the general gloom. This is a real problem for people suffering from depression. Not only do they have a selective memory for sad events, says Rebecca Elliott, from the University of Manchester, UK. They also dwell on negative thoughts and interpret things in a more than usually gloomy way. Once you become depressed, says Elliott, you can get locked into a cycle of concentrating on the negative, getting worse and worse in a downward spiral.
But is this really relevant to the rest of us? What of those who get just a little grinch-like at Christmas 鈥� should they be worried?
Well, maybe, cautions Elliott. Even mild forms of depression can lead to problems with memory and attention. 鈥淭here have been studies with seasonal affective disorder, which tends to be milder than major depression,鈥� she says, 鈥渁nd people have identified cognitive deficits even in those groups.鈥�
Is it more than just memory and learning that follow the tune of our mood? The answer seems to be yes. Mood also affects how well we can pay attention, the way we take in information, and even how we think. In fact, Fielder goes so far as to suggest that our brain processes information in completely different ways when we are in good or bad moods.
Walter agrees: 鈥淢ood is associated with a certain cognitive style,鈥� he says, 鈥渁nd this cognitive style makes evolutionary sense.鈥� A negative mood, he suggests makes you more realistic and more focused on the outside world. You need to deal with information in a direct, rapid and straightforward way. A positive mood, on the other hand, usually means you are not in danger, that you have time to introspect, to be creative, to play around with information 鈥� what Fiedler calls a 鈥渓oosened鈥� cognitive style.
So what should you do to ensure a happy mood? The answer is simple enough: get yourself feeling good to start with, and that should reinforce itself. There are plenty of ways to manipulate how you feel. These range from more serious options like antidepressant drugs to the everyday strategies most of us use without thinking: listening to happy music is a reliable one. Exercising, doing something you enjoy, or just smiling are also tried and tested methods. So there鈥檚 really no excuse for stewing in a miserable funk. After all, even the original Ebenezer Scrooge managed to cheer up when he finally made the effort.