Time is an elusive field - could it be that we are unable to perceive any given event exactly as it occurs?Aron Visuals

“The past is already behind you.” “Live in the moment.” Wise words we’ve all heard before, and ones that seem easy enough to follow. But what if, in reality, “experiencing in the now” is impossible? Recent discoveries in neuroscience show just how wonky our perception of time can be, with studies suggesting that what we perceive as happening ‘now’ could have already happened in the very recent past.

The theory behind this: our brains don’t directly record each instant as it exactly happens. Rather, they reorganise and reconstruct events from within a very short period of time to be able to make sense of the world through sequence. Therefore, the ‘present’ is not just one instant but has a duration.

This notion that “time is a construct” isn’t modern by any means – in fact, it can be dated back to 1882 in E.R Clay’s The Alternative: a Study in Psychology, in which he defines the duration of time which we perceive to be happening now as the ‘Specious Present.’ According to Clay: “the present is really a part of the past – a recent past – delusively given as being a time that intervenes between the past and the future.” Interestingly, the success of Clay’s seminal work can be partly attributed to Cambridge Philosophy Professor and Newnham College co-founder Henry Sidgwick, who gave it a glowing review in a letter to the Editor.

“The brain must be guessing ahead, predicting where the moving object will be in the future based on its past trajectory”

Neuroscientist David Eagleman has conducted a series of tests that seem to prove the existence of this ‘Specious Present.’ Firstly, he looks at the Flash Lag Effect – a visual illusion in which a moving object and a flash of light that appear in the same location are perceived to be displaced. More specifically, the moving object is perceived to appear approximately 84ms ahead of the flash in its trajectory.

Earlier studies suggest that this illusion arises due to ‘motion extrapolation’ – the brain must be guessing ahead, predicting where the moving object will be in the future based on its past trajectory, and forming its perception of the flash’s present position based on this prediction.

Eagleman disproves this theory. He sets up a test in which the moving object changes direction at the point of the flash. According to the extrapolation theory, the moving object should still be perceived to appear ahead of the flash, as this is where our brains would predict it to be. However, Eagleman’s tests show when the object changes direction, the exact opposite happens – is the flash that appears before the object, rather than the other way around. So, whether the moving object reverses direction or not, the flash is always perceived around 80 milliseconds after it actually happens. From this, we can gather that our brain’s motion perception is postdictive rather than predictive. When it records the moment of the flash, it is also taking into account all other motion that occurs within the next 80 milliseconds.

“When our brains are perceiving the present, they are really perceiving an 80-millisecond time frame”

Through this, we can see that when our brains are perceiving the present, they are really perceiving an 80-millisecond time frame – they sort through all the events that take place in it, and automatically synchronise them. In another experiment, Eagleman exploits this auto-syncing capability by setting up a device in which participations push a button and a light flashes 80ms later. Results showed that after only a short time, participants came to believe that the button push and the flash happen simultaneously, despite the 80ms delay. Interestingly, when the delay was removed and the button-push and flash really did happen simultaneously, many participants believed that the light flashed before the button was pushed. This is a prime example of the brain convincing itself of the simultaneity of non-simultaneous events, and the warped reality that it results in.

In these cases, the Specious Present seems like nothing more than our brains playing tricks on us. So why does it exist at all? Why do our brains insist on gathering all the events in a short period of time, syncing them, and then perceiving this as the present – why not just perceive each moment the instant it happens?


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Firstly, there are very practical benefits. For example, when we make rapid eye movements, our vision shuts down temporarily (around 50 micro seconds) in something called saccadic masking. Imagine if our brains recorded each instant of this – we would be seeing flashes of black each time we looked around.

Our auto-syncing abilities also allow us to perceive videos as one continuous stream of movement and corresponding sound, when in reality they are a series of static snapshots combined with audio that is usually played at a delay.

Equally significant is the importance of causality in our perception of time. In order to make sense of the world, our brains need context – we need to know where different moments are in relation to each other, in order to understand their placement in time. Just as we read the letters R E D to sequence and form a single concept of a colour, we gather multiple instances within a short time period to perceive them as a single moment.

So technically, we may be living 80 milliseconds in the past. Whilst 80 milliseconds may seem like nothing, it’s still enough time for our brains to unjumble all the information it receives and form its perception of the present, and also enough for this unjumbling to go askew.