Time in our heads

你还记得,小时候,旅行似乎take forever on the way there, but then much less time on the way back. Do the years seem to be flying past increasingly quickly? Why? Luke Jones is from the University of Manchester and he joined Chris Smith and Adam Murphy...

Luke - It kind of depends on what type of timing we're talking about. Although we talk about people who are having a sense of time, there's different types of timing judgment that we make. So you have a sense of duration, how long things lasted for. You have a sense of where you are in time, you know, when am I or what time is it now? And you have what we call passage of time judgment. So how quickly time seems to pass for you. And there seems to be different mechanisms that control these different types of timing judgment

Chris - And how good are we on average at working out how fast time is passing?

Luke - How quickly time is passing, we're very variable at it. In fact, it's a very weird question, if you think about it. We know that time passes at the same rate, unless you're close to a black hole or travelling at the speed of light. But if I say to you that time passed more quickly when I was playing on my Nintendo this afternoon, or that it crawled when I was waiting for a taxi to get here, then you understand what I mean. There seems to be this disconnect between our knowledge that time passes at the same rate and the way we feel time passing.

Chris - I remember reading in the book Catch 22, that the main character says he likes spending time during his days off with a certain other character 'cause that person's really boring and makes time go really slowly. So it seems to make the leave last longer. But why is that? Why do things that are very engaging seem to make the time whiz by, whereas things which are tedious seem to take forever?

Luke - So although we think of those two extremes, so the unpleasant situation, and the pleasant situation being kind of polar opposites of each other, they seem to operate in quite different ways. So in the pleasant situation, you're probably not paying attention to time. You're engaged in the event, you're not looking at the clock. And it's only when you receive a phone call, or something alerts you to what time it is, that you kind of retrospectively think, Oh my gosh, so much time's past. When you're in an unpleasant situation, you're aware of it at the time. You're aware of every single second ticking, ticking along and crawling along. So the, the, the pleasant situation of time flying seems to be a kind of retrospective or we look back and infer that it must have passed quicker.

Chris - I read one proposal by a group of experimenters, who were throwing themselves off bungee platforms while watching a watch, and saying their theory was that because they were taking more sort of, mental snapshots provoked by fear, their memory was much richer for the experience, that when the brain worked out, well roughly how long something had took, because it had so many mental images of what had happened in that period of time it assumed it must have taken longer than it did, which is what was creating the sense of time slowing down under that circumstance.

Luke - Yeah. So that's really interesting, so there seems to be, we haven't worked this out yet, but there seems to be an interesting link between the rate at which we process information, and our perception of how quickly or slowly time passes. So in those extreme situations, and a classic example is a car crash. So when people talk about that they say "it seems as if time slowed down, seems as if the van coming towards me was in slow motion." And you can imagine that in that situation you might have a kind of big injection of adrenaline, you know kind of fight or flight response, and this speeds up the rate at which you process information. If we're using that as a kind of feel of how quickly time seems to pass, then you can imagine that there'd be a link between those two things.

Chris - And do you think that that is what is happening with age then? That because we're processing information a bit less because there's less novelty in everything for us, it gives the perception that time is passing quickly because the brain's on autopilot more?

Luke - Possibly. The age thing is a really weird thing, the more you think about it. People have noted this idea that the time passes more quickly as you get older for hundreds of years, and there's an old idea of a year being a smaller and smaller ratio of your age as you get older, or maybe you process less information, but hardly anyone's actually collected any data on this and those that have, have found that it doesn't quite scale up in this way. So in order to feel that time is passing twice as quickly, you might need to be four times as old. And there's some evidence that it actually peaks in middle-age rather than carries on going as you get older. But the real mystery is what do people really mean? Is the question meaningful? If I ask you how quickly time passed now compared to when you were half your age, you'll give me an answer, but do you really carry around in your head a model or a memory of how quickly time passed when you were younger?

Adam - I find myself every autumn starting to say things like, "Oh, Christmas is coming earlier every year." What's going on there?

Luke - Now, isn't that strange? Do you think that you would update your notion of how quickly Christmas comes around? Well, why? Why are you caught out every single year? It's quite an odd one that. Again, it's whether that question has meaning. We've certainly feel it and people talk about this anticipation of Christmas, but it's odd that people don't update their notion of how quickly it takes for a year to pass.

Chris - And Luke, are there any things that can go wrong that will affect our sense of timing? 'Cause we've talked about healthy people all the way through so far. Are there any situations where people's time clock goes wrong and their perception of time is off?

Luke - There's very little evidence. It seems as if there's something so intrinsic about your sense of time, or at least your orientation in time that if you lose that you've kind of, you've already lost a lot of other cognitive strategies. So actually looking at those cases, there's hardly any of them to draw any conclusions from.