Humans have a cognitive ability that no other animal seems to have. We can mentally time-travel. At will, we can think back to the past, reimagining our first day at college or eating a meal last week. Then, just as rapidly, we can switch to picturing the future, imagining our next holiday or drinking a cup of tea in an hour’s time.
This isn’t about knowing something has happened, or will happen, but experiencing it in our minds. It’s the difference between knowing that when summer comes, the weather will be warmer, and imagining yourself sitting in the sunshine next summer, feeling the heat on your skin.
The experimental psychologist Endel Tulving described mental time-travel as part of autonoetic consciousness – the sense we have of ourselves as persisting across time. We can both re-experience and pre-experience events.
If you are meeting some friends for lunch, your prospective memory reminds you to turn up on the right day, but you can also picture yourself finding a table, reading the menu and ordering your food. This is different from actively planning.
This is one of the skills unique to humans, according to the Thomas Suddendorf, author of The Gap: The Science Of What Separates Us From Other Animals, who is based at the University of Queensland.
The ability to time-travel mentally has allowed us to imagine different futures and to produce the complex world we live in today. By recombining old memories, we are able to project ourselves forward in time, giving us endless combinations from which to select the most plausible possibilities.
Babies are also forced to live in the here and now, unable to escape mentally into the future
Like a remix, utilising these memories allows us to preview future events in a window in the mind. This is key to the extraordinary ability of humans to adapt to their environments.
Suddendorf says this is one of the factors that makes us unique. “We can do nested scenario building, that is we have an open-ended capacity to imagine alternative situations, to reflect upon them and to embed them into larger narratives. It’s a tremendously powerful skill. We can imagine situations like what we’re going to do tomorrow, next week, where we’re going to have a holiday, what career path to pursue, and we can imagine alternative versions of those. And we can evaluate each of them in terms of their likelihood and desirability.”
This allows us to shape the future to our own design and to seek opportunities and avoid threats before they emerge.
Other animals can’t do this in the same way. Suddendorf says psychologists believe that your dog doesn’t lie by the fire reminiscing about its favourite walks and hoping to return to that special field where they once found a dead rabbit.
Babies are also forced to live in the here and now, unable to escape mentally into the future. It is not until the age of three or four that they begin to be able to imagine a future where they might feel differently, where they can anticipate or fear events.
In one experiment only a third of three-year-olds could give a plausible answer as to what they might do the next day, but within a year or two their sense of the future has developed to the extent that two-thirds of them can do it.
Sometimes our ability to time travel in our minds brings us distress
This suggests that small children have an extreme form of the empathy gap we can all experience on occasion which leaves us unable to imagine that we might feel differently in the future. When I packed my suitcase on a dreary November day in London to go to Sydney where I knew temperatures were high, I still couldn’t resist packing a jumper and puffer jacket. It was impossible to imagine that I wouldn’t need them.
Of course, neither garment left my suitcase.
But sometimes our ability to time-travel in our minds brings us distress. Helen Christensen, chief scientist at the Black Dog Institute in Sydney, told the audience at the World-Changing Ideas Summit “the capacity of imagination means that sometimes people do ruminate about the future and also looking backwards people can be traumatised, reliving their experiences, which can be incredibly upsetting and can interfere with happy functioning”.
But she hopes that technology can come to the rescue. Her team have been experimenting with using techniques from cognitive behavioural therapy online and via apps. Fifteen years ago they developed Mood Gym, an online course of cognitive behavioural therapy that has since been used in more than 200 countries around the world. The found the anonymity of this approach means they can reach people who don’t want to come forward and talk to a real life therapist.
Now they’re looking to social media to try to identify people who might benefit from such a course. Using machine learning and artificial intelligence they’re hoping to pick up the signals young people are giving out when they post on social media.
“We’re doing a large number of experiments where we’re trying to look at the content and structure of language to see whether that will give us clues as to a particular problem. For example, were finding that bipolar communities often talk about the medication they’re taking. Groups that hang together online because of self-harm are often angry. We find that depressed people use more personal pronouns.”
The skill of mental time travel has on the whole served us well, but in the future might we evolve to avoid these mental health difficulties
If they can identify people at risk, then the question is what to do with that information and how to intervene. They might be able to place adverts for online CBT to appear in social media if particular keywords or search items are used, in a similar way to marketing companies who already personalise adverts.
“It sounds Big Brotherish, but on the other hand we have already developed a large number of apps and online programmes that are effective in reducing suicide risk, anxiety and depression. So we have the digital tools. It’s a question of how can we do the research involving young people and others to identify the best way in which to deliver this information and help to them.”
The skill of mental time travel has on the whole served us well, but in the future might we evolve to avoid these mental health difficulties? Will depression always be with us? Suddendorf says he almost hopes so.
“At least in their mild forms, depression and anxiety are part of our mental repertoire for how we deal with the world we’ve developed. We get depressed when we pursue options that are not successful. That motivates us to withdraw from that situation or it signals to others that we might need help.
“Anxiety is useful in that when we simulate future events we have an emotional reaction that makes us feel anxious. That motivates us in the here and now to do something about that event – to run away or to prepare. That makes us better able to cope with a future event. So these mild versions might be functional. Of course I hope that more serious clinical disorders can be dealt with.”
Claudia Hammond is the author of Time Warped: Unlocking The Mysteries Of Time Perception, published by Harper Collins.
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