Imagine a fender bender at an intersection. It’s a common occurrence and, usually, someone is at fault. But ask any police officer and you’ll find the blame may not be all that easy to determine. The stories from the drivers involved often oppose one another and eye-witness reports also may reveal striking differences in how the accident unfolded.
You might believe the lack of harmony amongst statements is due to personal and material attachments to the event. You may be right. But there could be another reason for the divergence in testimony. It’s related to the fact that our actual perception of the timing of events varies as a function of our role in reacting to or causing those events. Just how these distortions in time perception occur is not well understood.
New light is being shed on how such temporal distortions occur by the work of Prof. Mel Goodale and his team at Western University’s Brain and Mind Institute. Together with postdoctoral fellow, Dr. Yoshiko Yabe, Goodale has been exploring how our own actions can affect the timing of events. The work, now available in the journal Cognition, http://www.sciencedirect.com/science/article/pii/S0010027716302438 reveals a fascinating game of push and pull in the brain that ends up changing the way we perceive time.
Goodale and his team asked volunteers to listen for a particular auditory tone and then report on the time the tone occurred. It’s a relatively standard test conducted in many labs to understand our perception of an event. For most people, there is about a tenth to a quarter of a second lag from the actual time. In this part of the study, nothing was different from what has been found before.
But this was merely the control condition. For the next part of the experiment, Goodale added a twist in the form of an action. In one experimental condition, the volunteers were asked to perform a hand movement in response to the tone. In another condition, the tone was presented after the hand movement (as though it had been caused by the volunteer’s action). When the tone triggered a hand movement, many of the volunteers reported hearing the tone even later than they had in the control condition. But when the tone was presented after the hand movement, the perception of its timing was early. All of this suggests that the perceived time of the tone was drawn towards the action, a kind of temporal binding.
This experiment provides some insight into what might happen when two drivers are waiting for the light to change. The driver in the back might perceive that the light turned green later than it really did, linking that event to the action of hitting the gas, just as in the experiment. But for the person in front, who might be thinking about something else, the temporal binding would not have occurred, just as in the control condition. The difference in the perceived timing of the green light and the accident that followed could lead to very different reports as to what happened.
While these results provided a possible explanation for differences in time perception for events that trigger actions, Goodale’s team wanted more. They wondered if temporal binding could be manipulated by looking at a longer sequence of actions and events. After all, in real life, sensory events often trigger actions which in turn result in other events unfolding. If events are drawn towards actions, then the timing of both the triggering and the resultant events should be affected.
They performed the experiments once again, but this time the action that triggered by the first tone was followed by a second tone a quarter of a second later – so that again it appeared to have been ‘caused’ by the act of moving the hand. Half the participants were asked to report on the timing of the first tone while the other half reported on the timing of the second one. If action was the key to the perception of time, the first tone would be perceived to have occurred later than it really did while the second tone would be perceived to have occurred earlier.
This is exactly what happened. The first tone, as usual, was reported to have occurred a fraction of a second late. In contrast, the perception of the second tone was early. In short, both events were being pulled in time towards the action. Goodale has proposed that this kind of temporal binding may enable us to identify the causal links between the world of sensory events and our actions in that world – by flagging those events linked to our own behaviour.
The results of this study open the door for future studies on temporal binding. With the focus of time perception clearly placed on action, researchers can begin to determine which pathways in the brain are responsible for linking together sensory events and motor behaviour. This in turn can help us better understand the mechanisms underlying consciousness.
Perhaps more importantly, the information from Goodale’s lab may lead to further studies on how best to predict and account for differences in the perception of time. After all, if there is a way of disentangling differences in how people perceive time in accidents and other situations, drivers and law enforcement – as well as insurance companies – would love to know about it.
Read the original research article:
Yabe Y, Dave H, Goodale MA. Temporal distortion in the perception of actions and events. Cognition. 2017 Jan;158:1-9. doi: 10.1016/j.cognition.2016.10.009.
