How would time travel change legal proceedings

memories of the Future

Research Report 2019 - Max Planck Institute for Human Cognitive and Brain Sciences

Max Planck Research Group "Adaptive Memory"
We humans are not stuck in the here and now: Thanks to our memory, we vividly relive events long past. But memory is not only used for memory. With its help, we can also imagine future events as if we were actually experiencing them. So we are able to go on mental time travel. This sometimes helps us make better decisions. And we even learn from such imaginations as if we had actually experienced the imagined.

On a mental journey through time

If you ask study participants in the magnetic resonance imaging (MRI scanner) to remember both the past and the future, then in both cases essentially the same network of brain regions is active. A similar picture emerges when one looks at the consequences of damage to certain parts of this network: They not only impair our memory performance, but also make it impossible to imagine new events. These findings suggest that our ideas about the future are crucially based on our memories.

In a sense, our memory supplies the fragments from various past experiences from which our imagination assembles new episodes. For example, based on my memories of various stays in the mountains, I can imagine what it would be like to climb Mont Blanc. Memory is therefore not a purely backward-looking ability, but rather a predictive ability of our brain. This allows us to plan for the future - for example, which equipment I should take with me for mountaineering. In particular, it also conveys the feeling that would arise when experiencing a potentially new situation - such as the feeling of happiness when reaching the summit.

In previous studies, we have shown how this imagined future can help us make better decisions. It becomes more likely that we will forego a short-term reward (such as enjoying a chocolate cake) if we imagine what will be more rewarding for us in the long term (such as being in shape at the next city run). Our latest studies also show that we even learn from such pure ideas about the future - just as we do from actual experiences.

How we learn through visions of the future

There are, for example, the places with which something suddenly connects us - such as the inconspicuous street corner where you were kissed for the first time. Before we didn't even notice these places, but through special experiences with loved ones, the brain transmits positive emotions to them. Our attitude towards these places is changing: They are becoming especially valuable to us. In a new study with a colleague from Harvard University, we tested the idea that such evaluations can be influenced not only by real experiences, but also by pure ideas.

We first asked our study participants to name people they like very much and also those they don't like at all. In addition, they were asked about places that they classify as more neutral. When the subjects later lay in the MRI scanner, they vividly imagined how they would spend time with the very popular person in one of these neutral places in the future. In their imagination, they should also interact with this person. So I could imagine how I am in the elevator of our institute with my daughter and she presses all the buttons impetuously. Then we drive to the upper floor, where I would get out to show her the terrace.

After scanning, we were able to find out through repeated tests that the attitudes of the study participants towards the locations had changed: They preferred the previously neutrally rated locations to those at the beginning. We first observed this effect with study participants in Cambridge and were later able to show it again in Leipzig. Only by imagining a meeting with a loved one in a particular place can the emotional value that person possesses for us be transferred to that place. We learn in the same way as if we had actually experienced the imagined event.

With the MRI data, we were able to show how this mechanism works in the brain. A region in the front of the brain, the ventromedial prefrontal cortex, plays an important role. We assumed that in this region representations of our environment are bundled and combined into an overall picture. For example, there would be a representation there with information about my daughter: what she looks like, what her voice sounds like, how she reacts in certain situations. Our results support this hypothesis.

These representations also include a rating - for example, how important my daughter is to me and how much I like her. When subjects thought of a person they liked better than another person, we saw signs of increased activity in that region. When I imagine my daughter in the elevator, both her representation and that of the elevator become active in the ventromedial prefrontal cortex. This can lead to links between these representations - the positive value of the person is transferred to the previously neutral place.

Do ideas contribute to the development of mental disorders?

Just as we remember the past, we can also imagine the future - both are based on similar processes in the brain. This mental time travel ability has great advantages in decision making and can also help us avoid risk.

In a further research step, we will also deal with the power of negative thoughts. Just as pure ideas lead to things being assessed more positively, this mechanism could also work the other way round. What significance would this have for people who suffer from depression? Do they create a negative image of the world by devaluing actually neutral things with negative thoughts? Hopefully we will be able to answer such questions soon.


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