The Enigma of Time

Lynne Malcolm: You know that time is constantly ticking away. Why is it then that time can drag by excruciatingly when you're bored, and then again it flies by when you least want it to?

Muireann Irish: Time perception, memory and the self are absolutely intertwined. So we only perceive the passing of time in relation to the events that we've experienced as individuals, and then we perceive getting older in relation to having clear, demarcated chunks of time that we can estimate have elapsed since we've experienced other forms of events.

Marc Wittmann: When people have to judge duration of many seconds intervals through the feeling of our body over time we sense duration, and that's why it's important because when we are overly-sensing our own bodily feelings, time expands a lot.

Muireann Irish: Perhaps we could, by virtue of some of these theories, then become masters of the way in which we experience time.

Lynne Malcolm: Cognitive neuroscientist Muireann Irish, and psychologist Marc Wittmann.

You're with All in the Mind on RN, I'm Lynne Malcolm. Today the enigma of your experience of time.

Scientists first began to study time perception experimentally in the late 19th century. But now, interest in the way we perceive time, and the brain processes involved, is having a revival.

Psychologist Marc Wittmann studies human time perception at the Institute for Frontier Areas in Psychology and Mental Health in Freiburg, Germany. Using psychological and brain scanning techniques he's found out how much time we can estimate with any accuracy.

Marc Wittmann: Up to 2 to 3 seconds, so very short periods of time actually, people are quite accurate. So they can involuntarily tap with their fingers for this certain amount of time, they can judge durations. And the explanation is that up to 2 or 3 seconds you are within a time range where you are used to do sensorimotor timing, so you are walking, talking, sports, music, mountain climbing or whatever. So within this motor range of your behaviour, you are very accurate because you have to react precisely, press a button at the right point, with your steering wheel in the car you have to be of course very accurate to avoid accidents. But then beyond that, even if you're talking about 10, 15 seconds, people subjectively tend to get more lost in time and they get very fuzzy judgements.

Lynne Malcolm: There's still no real consensus in the science of time perception, about how and where in the brain, time is processed. However, Marc Wittmann is excited about his own theory of subjective time perception. You'll hear more from him later about how he relates time perception very closely to the physical body.

Even though you know that time is measurable and finite, your perception of it varies widely. Neuroscientist Muireann Irish is Associate Professor at the Brain and Mind Centre at the University of Sydney.

Muireann Irish: Our perception of time is linked to a number of different factors. So it's been suggested that our mood can have a huge influence on the way that we perceive the passing of time. So we know that as well the activities that we have concurrently at play at any one time can also influence the way that we perceive how the events of our day are unfolding in the speed at which we are perceiving these events. So, for example, we know that when we have less to do and we have time on our hands, this can actually feel excruciating because our idle brain is wondering when the next event is happening, what's coming next, and it can feel almost painful sometimes to have too much time on your hands. Also the old adage of 'a watched pot never boils', if we are waiting for something to happen, without filling that time for ourselves, the time can dilate and actually feel as though it's been a lot longer in duration than it actually was.

And at the same time, attention may play a big role again in how we experience different events. So if we are multitasking and we are extremely busy, then we can have this time contraction affect where the day seems to go by extremely quickly and we can't figure out where all those hours went. So it has been suggested that maybe this is attentional, largely modulated by the fact that we only have an allocated amount of attention that we can direct to what we have ongoing at the time. And so when we have this finite set of attentional resources and they are currently used, then our ability to monitor and keep track of time and keep track of minutes and hours is much less likely to be able to be as engaged as when we have less on our hands.

Lynne Malcolm: One phenomenon that I've noticed is that when I am working at the gym and I set myself a period of time to do something with exertion, the time seems to drag or I'm watching the time, I'm trying not to think about the time. So why is that, that we are wanting to pass time with an activity but we don't seem to have the control over how we perceive it?

Muireann Irish: Again, I think this relates a lot to motivation. And so, some of the time, perception theories that are in the field at the moment talk about the role of goals and motivation in terms of how we perceive time. So in the gym, assuming that that's not your favourite activity in the world, it's the idea that we are doing something to kill the time and to pass time. And it's been suggested that the way in which we couch our activities in emotional or positive and negative terms can influence actually how we perceive the duration of those events. So, for example, if you are looking forward to an event, it can seem that the time is dragging and that it can't get here quickly enough. So a child that is looking forward to Christmas…for example, if you are not looking forward to something and you have a negative appraisal of an upcoming event, like giving a speech or having to do a presentation at work, the days can just roll by extremely quickly and all of a sudden you are there.

And so it's this positive versus negative appraisal of the event that we are looking forward to or not looking forward to can really influence then anxiety or motivation and whether the time feels that it's dragging or actually moving very quickly.

So emotion seems to really colour our experiences and we know this from the memory literature, that emotional events are remembered in indelible details. So they can be extremely exquisitely vivid and profound, these experiences, and we take them through our lives with us, and they confer a sense of who we are and a sense of identity.

Our perception of time seems to hinge upon the emotion that was experienced at the time of the event. So, for example, we know that this time dilation effect seems to be particularly enhanced when people have negative emotional experiences. So particularly traumatic events or harrowing events, we know that people have experienced attacks or particularly traumatic car crashes, will say that the whole event plays out almost in slow motion, and that the time, it just seems to have gone on for hours rather than just a few brief moments.

And so experimenters have taken different approaches to stressing people out and trying to understand their perception of time during negative experiences, and it seems to be it's more a function of our memory systems again. So when we are afraid, our amygdala, which is a very evolutionary old structure in the brain, it's shaped like an almond and it's deep inside the brain, it is really important for emotional experiences. And when the amygdala fires in relation to negative or fearful experiences, it actually enhances our ability to lay down the details of that experience.

So, in the car crash example, our amygdala would fire, we would start to become really attuned to all of the details in our environment, and a very vivid, evocative memory is created. So our perception of time at the point of the experience is actually as it would be in everyday life, but it's our replaying of the event which happens in a much more drawn-out lengthier away, in much more vivid detail which actually would confer an adaptive benefit for us in terms of our evolutionary history, that we would remember these important events in much more detail. So it's a trick of memory. The event is experienced in real time but our reliving of it appears to be much more stretched out and slower.

Lynne Malcolm: I'm sure you'll agree that time seems to speed up exponentially as you get older. One popular explanation for this is known as the proportional theory. It was put forward by Paul Janet in the 1800s. He suggests that we perceive time in proportion to the length of time we've been alive. So one year out of a five-year-old's life seems much longer than one year out of an 80-year-old's life. But Muireann Irish says this doesn't account for the fact that we don't actually feel time speeding up as we're experiencing events in our lives. Time has gone quickly only on reflection.

Muireann Irish: One of the more current theories then is that memory has a huge factor to play in the way that we perceive time and that basically our lives are punctuated by key events that define who we are and that we have much more of these formative events when we are younger. So you have your first-time experiences, like your first date, your first kiss, getting married, your first child, and that these are so central to our identity that we really remember them in vivid detail, and we have less of these experiences then as we get older, so we can feel like we've moved a lot further away from that defining period and that time has moved a lot more quickly.

Lynne Malcolm: So that is really based on a very close relationship between our time perception and our memory.

Muireann Irish: Absolutely. So memory seems to be quite a cornerstone of our ability to perceive time. And then we see altered time perception in populations who have disrupted memory or memory dysfunction.

Lynne Malcolm: What are the main areas where people's time perception and memory are disrupted?

Muireann Irish: Certainly in Alzheimer's disease, that would be one of the most canonical conditions in which memory is compromised. There hasn't been a lot of literature investigating time perception in the dementias, but certainly the studies that have looked at this have suggested that there are definitely problems in being able to estimate the duration of events and being able to calculate time duration. And again, it's been suggested that time is perhaps perceived as being speeding up in Alzheimer's disease because there are less of these events that the individual can remember to, again, break up their daily lives. And so when they are looking back over the recent period, which is where the memories are most vulnerable in Alzheimer's disease, in fact there's nothing there to draw upon. And so the individual is again looking further back over their lifespan and wondering how that is so far away from the present moment, and that time then is perceived as having passed much more quickly.

On a day-to-day level in Alzheimer's, again the inability to actually lay down new events and to experience and encode new memories, that may give the impression that time is passing much more quickly. And so individuals end up being much more present, focused, because memories are unable to be retrieved or laid down efficiently.

Lynne Malcolm: Muireann Irish.

You're with All in the Mind on RN, I'm Lynne Malcolm. Today, the puzzle of time. Why does it seem to pass at different rates, depending on what else is going on for you?

Psychologist Marc Wittmann studies time perception at the Institute for Frontier Areas in Psychology and Mental Health in Freiburg, Germany.

He says that we all have a type of internal clock, but your specific approach to time can't be explained by individual brain differences. However, your perception of time is related to your level of impulsiveness.

Marc Wittmann: So it is a really strong relationship between time perception and impulsivity. I think every parent knows this with their children who just want…'when are we arriving', when children are in the car, yes?

Lynne Malcolm: Yes, 'Are we there yet?'

Marc Wittmann: 'Are we there yet?' 'When does the TV program start?' So this waiting time is something in general more impulsive individuals have problems with because they cannot stand to wait. And what happens is that time expands in subjective duration, and people want to have the end of a waiting time. And so this is a very clear association in science and you could say more impulsive individuals, they overestimate duration and they feel that the passage of time to move on more slowly, with all the consequences, that they then have some sort of erratic responses or leave the room or get fidgety or get angry and you have then all these other things like aggression, which come together with impulsivity.

Lynne Malcolm: And what about boredom, the relationship between feeling boredom and one's sense of time?

Marc Wittmann: Yes, so boredom of course is maybe actually the paradigmatic example of how subjective feelings and subjective time are related, because what is happening in boredom is you are very much related to yourself and your bodily self. You are not distracted by entertaining activities. Again, it's a waiting situation maybe and you don't know what to do. You cannot do anything exciting. And then you are focused on your bodily self. You suddenly get more aware of yourself and then time stretches. And this is I think a key to the understanding of how time is generated, subjective time, is that maybe subjective time is generated through the bodily self. And also of course then through the brain areas that are related to the bodily self.

And this is one…this is actually my idea and the idea of other scientists, that through insular cortex activity, that's a certain brain region, the insular…a very nice name because it means 'island of the brain'…which is responsible for integrating all the bodily signals. And because of insular cortex functioning we sense ourselves. If we are feeling hot or cold, if we are feeling itchy, if we are feeling thirsty, hungry or have pain, then the insular is very active because it gets all the information from the body. But then also we have shown in our studies that the insular cortex is also related to subjective time. When people have to judge duration of many seconds intervals, also insular cortex activity can be seen. That means that through insular cortex activity, meaning through the feeling of our body over time, we sense duration. And that's why in boredom, because we are overly sensing our own bodily feelings, time expands lot.

Lynne Malcolm: So can you explain some of the study and the research that you've done that brings you to this conclusion around the relationship between body and sense of time?

Marc Wittmann: Yes, so the initial spark was a study actually with impulsive individuals. So we wanted to have longer time intervals so that people really would feel empty time. Actually it was about nine seconds, 18 seconds intervals, which are quite a long also in the fMRI scanner environment, which hasn't been done before, but we really wanted to have this because we wanted to later study impulsive individuals, which we also did.

For the first study we just took normal students with different levels of impulsivity, we didn't look into impulsivity itself, then had them judge duration of three, nine and 18 seconds intervals. And this is where we showed how the accuracy in judging durations of these intervals was related to insular cortex function. So the insular, as I said, this primary interoceptive cortex…what does interoception mean? Interoception means the feeling of the bodily self. And this region was also involved in time perception. So our interpretation then was that because this was still the open question, the mystery we wanted to solve is maybe subjective time is generated through the feeling of the bodily self. And this was the beginning.

And then later we also showed that when we looked at physiology measures like the heart rate, the breathing rate, we could also show that the breathing rate and the heart rate were related to subjective time. So the breathing rate we have some sort of control over how fast we breathe, but the heart rate is actually not that easily controllable or not directly controllable, but still we could show that when people had to judge the duration, again eight seconds, 20 seconds, in this time range, that the heart rate slowed down while people were judging duration. And this slowing down of heartrate stopped at the end of the interval.

So we cannot control this slowing down or speeding up of the heartrate, but nevertheless it was involved in the judging of duration. So this was a very strong indicator that our physiological states, our body states are actually involved in judging duration.

Lynne Malcolm: And so that's very related to being self-conscious and even…is it also related to consciousness itself?

Marc Wittmann: Yes, so you could even say self-consciousness, for example, that has also been shown in studies when people are embarrassed in a social situation, that subjectively time expands, they become suddenly self-aware. And this also relates probably to insular function. They become self-aware of themselves, of the embarrassment in the social situation, and then time suddenly expands, time slows down. And so you could even say also in the definition of consciousness, consciousness is not the individuated experience of yourself in the world but always in relation to others. So the idea could also be that how does consciousness evolve? Through social interactions because we get aware that other people are watching us and we are in interaction with others, and that consciousness arises from this social interaction. And so again we have self-consciousness, bodily feelings and social interactions which create this self-consciousness.

Lynne Malcolm: Since you've made the connection between the body and our perception of time, how do you suggest we can use this psychology of time to our advantage and extending and expanding our experience of life?

Marc Wittmann: If someone is totally stressed out in his work life and he feels, oh, I cannot cope with this, the work schedule is so tight and I cannot cope with this anymore', what I always do or say is giving a paradoxical intervention and say now leave the room, go out of the office building, even if it is just five minutes. You then feel yourself again, you are then out of this autopilot mode, out of this stress mode, and suddenly time passes very slowly again because then you feel yourself, you could say insular cortex functioning is coming back to your awareness because you feel your bodily self again.

What also happens through these pauses is that something is actually organising itself in your brain and you may not even be aware of but then when you come back to your workplace, not only do you have this feeling of, oh, actually time can pass very slowly, but also some things have rearranged in your thoughts and you then know better how to cope with these things. So these individual pauses in-between I think are very healthy to just to get out of this autopilot mode and this helps a lot I think.

Lynne Malcolm: Marc Wittmann from the Institute for Frontier Areas in Psychology and Mental Health in Freiburg, Germany. His book is called Felt Time: The Psychology of How We Perceive Time.

The ability to perceive time accurately is related to behaviours and social functions that you probably take for granted, such as communication and predicting events. It's known that in some clinical conditions such as schizophrenia and Parkinson's disease, time perception is compromised.

Muireann Irish gives another example:

Muireann Irish: One of the syndromes that is probably most interesting from a time perception perspective is that of autism. And so we know that children with autism are actually particularly sensitive to delays and they find it very stressful to have to delay gratification or to wait. And it has been suggested that their time perception, their inability to actually gauge the passing of time in the same way as we would makes any sort of lag between a request and the outcome seem absolutely intolerable. And so it's been suggested that perhaps children and adults with autism have developed ways of coping and some compensatory strategies such as using ticks or tapping or stereotype behaviours to fill this large chunk of time that they are perceiving between the request and actually the outcome that they are looking for. And so it seems that even a second for a child with autism may be really intolerable, whereas they will fill the time then with these certain behaviours to try and overcome their unease and their stress.

Lynne Malcolm: That's interesting and it seems to relate to some of the work that Marc Wittmann is doing. He is looking at how time perception is very much related to our bodily movements.

Muireann Irish: Yes, I think that's an interesting parallel in that these individuals who have autism may actually be using their body as their own internal pacemaker, their own internal clock, whereas we tend to rely much more on the external environment, like watches and alarms. And so maybe it suggests that when other cognitive resources are compromised, that we need to retreat to our internal mechanisms that are more physically oriented, such as in the case of autism where they are using their own means of tapping or watching or vocalisations to try and fill the time and make it more meaningful for themselves.

Lynne Malcolm: And I guess that's something that we would all do to some extent, in a sense time is embodied.

Muireann Irish: Yes, absolutely, there's a huge movement towards looking at embodied cognition and how we can understand all of these manifestations of purely cognitive functions but more in terms of how they manifest physically as well and what we can do then to support these functions in our everyday lives.

Lynne Malcolm: And how do you think it relates to the sense of ourselves and perhaps even our consciousness?

Muireann Irish: I think time perception, memory and the self are absolutely intertwined. So we only perceive the passing of time in relation to the events that we've experienced as individuals and then we perceive getting older in relation to having cleared demarcated chunks of time that we can estimate have elapsed since we've experienced other forms of events. So I think the passing of time is crucial to conferring a sense of identity as we age, and then that might be why we feel so rueful or why we feel that time is passing so quickly, because we actually are moving away from who we were as a younger self and moving into a new chapter in our lives, and that can bring changes as well as we get older, so we can start to view events in a different way.

It's been suggested that when we do start to reach the later years of life, that older adults start to look back over their memories and recasting them in a more positive light, and even negative events that had happened can tend to be cast within a more positive appraisal, so trying to derive meaning out of possibly negative experiences and looking in a more generative way across the lifespan. So time passing can actually heal some wounds that have happened and make for a more concerted effort to kind of consolidate everything that's happened across your life into how that has shaped you as a person today.

Lynne Malcolm: I think you've suggested that because our time perception is so variable and so individual, we can actually be architects of our own sense of time. Just explain a little bit more about what you mean by that.

Muireann Irish: Yes, this is a really interesting idea that perhaps we could, by virtue of some of these theories then become masters of the way in which we experience time. And so we know that the busier we are and maybe the more positive the events are, that time seems to pass much more quickly. So the 'time flies when you're having fun' sort of idea.

But also there's been research to suggest that memory is so important for our perception of time and that the more events that you cram in, for example into your weekend, while the time at that point of experience may seem to pass relatively quickly while you're having fun, actually when you look back on the time at a later point it will feel that it was actually much more of an extended period because you had more memories in there which are punctuating that time period. So it's almost a paradoxical relationship between having a lot of events and not having the attentional resources to perceive them all at that time of experience, so the time passes quickly, but then in hindsight the memories will play out much more slowly.

Lynne Malcolm: Muireann Irish. Time perception is being discussed with great interest, not only in the fields of psychology and neuroscience but it's also a hot topic in the world of philosophy as well.

Muireann Irish: It's really interesting that we've seen this movement actually within the cognitive neuroscience literature to now view memory as it's the what, where and when. And to date we've been focusing on the what happened and where it happened. So we always look at the event details and the spatial location. But there really has been a shift towards looking at the time, so the temporal aspect. And we are seeing this in how the field is actually evolving and unfolding into looking at past and future and how they are inextricably linked. So our memories from the past serve this adaptive function to enable us to look forward, shape who we are and who we might be in the future.

And it's interesting from a very anatomical perspective, that the key structure that regulates memory and actually enables us to look ahead and envisage the future, so this is the hippocampus, it used to be traditionally just associated with space and the representation of space and how that might help us to consolidate events, but now actually people are talking about the presence of time cells in the hippocampus, and that the hippocampus might actually code for space and time, bringing all our events together. So it's interesting that in the philosophical world we are now starting to see parallels filtering in to the neuroscience literature to try and give us a better composite view of what time means in relation to memory.

Lynne Malcolm: Associate Professor Muireann Irish from the Brain and Mind Centre at the University of Sydney.

Thanks today to sound engineer Andre Shabunov.

I'm Lynne Malcolm, it's been great to have your company, catch you next time, in what will seem like the blink of an eye.

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