A new study this week has found that, in order to keep track of time, our minds exploit as many clues in the environment as they can get hold of. This means that our internal clock isn't solely controlled by pre-programmed cells in the brain.
Researchers from University College London have shown that some of our perception of time is governed by observing how much the world changes. The researchers also think that through life we have learned that things in the environment change at an 'average' rate. So if we compare the changes we see to the changes we expect, our minds can estimate how much time has passed.
Publishing in Current Biology, the researchers used two experiments to test their theory. For the first, twenty participants observed blobs of projected light appear twice. They were then asked which appearance lasted the longest. The light blobs were then projected alongside a mottled pattern which was programmed to change randomly, but at a regular average rate. This addition actually improved the participants' time judgements - which suggests that their brains used the rate at which the patterns changed in order to construct an internal time reference.
For the second experiment the authors varied the rates at which the patterns changed and then asked the subjects to judge how long the mottled patterns lasted. When the patterns changed faster, the test subjects thought they had lasted for longer, demonstrating that a change in sensory input can alter our sense of time.
Dr Maneesh Sahani, who led the research, believes that because of the various types of sensory input and analysis that go into this timekeeping, there may be no single area in the brain responsible for it.