Is our consciousness continuous, or does it occur in discrete pieces? At first glance, this may seem like a strange question. It seems to us that our lives are like a movie, where we perceive and are aware of every waking moment.

However, scientists, philosophers and neuroscientists have debated it for 1,500 years. Saint Augustine, one of the first great philosophers of the mind, reflected on how we might be present in short periods of time while perceiving movement. Even further the Abhidharma School of Buddhism Discussed Discreet Events of Consciousness rather than a continuous flow.

Modern interpretation? Consciousness can be discreet. We can only be aware for short periods of time for certain finite periods of time.

It may sound absurd. But think about how it feels when you wake up or when you start to fall asleep. Think about how you can “log out” when you’re doing a mundane task you’ve done a million times before. In these cases, it is a little easier to believe that we may not be really aware all the time.

In an opinion piece published on September 3 in the journal Trends in cognitive science, a group of scientists from Psychophysical laboratory, Brain Mind Institute, at the Swiss Federal Institute of Technology (EPFL) in Lausanne, Switzerland reviewed existing studies. They came up with a model that combined the continuous and discrete model of consciousness to illustrate how and when we are aware.

To see how it works, imagine you fall off your bike. If we were conscious throughout the fall, we wouldn’t be able to process the fall fast enough and could end up falling on our face. But in their model, we’re actually going through a period of unconsciousness, where our brains are furiously doing calculations – how fast you were going, if the road is asphalt or gravel, if you land on your wrists or on the side. This is followed by a much shorter period of consciousness.

“We have shown that you only become aware of an element after a substantial delay of around 400 ms,” explains Dr Michael Herzog, study leader. “The unconscious processing is continuous, but the conscious precepts are limited to certain short moments. “

Various experiments have confirmed this idea. For example, in several experiments (here, here and here), participants saw two superimposed lines with a delay of 40 ms. Participants said they saw only one line. In another experience, participants were shown a red disk for 40 ms, followed by a green disk for 40 ms. Participants reported seeing a disc – a yellow one – a visual combination of the green and red discs. Other experiments indicate that this delay between observation and awareness varies in duration, depending on the environment and the situation.

Similar experiments also show that this delay is present in our perception of sound. Another example is with touch, called the “rabbit” effect. If your wrist and elbow are affected in quick succession, it will sound like someone is drawing a line down your arm. It’s even stranger when you consider that there would be no way to feel this sensation until your elbow is hit. Therefore, it seems that your brain is interpreting the sensation after the wrist and elbow were affected.

The “unconscious processing” time may vary depending on the situation. In some cases it can be longer. For example, imagine you see a car driving on the road. At night, it may take you longer to tell the car is red, where your eyes receive less information in a noisier environment. During the day, in a well-lit situation, this treatment would occur more quickly.

These seem to indicate that we are not instantly aware. Our eyes and brains take a long time to process – and this results in a delay in our awareness.

We have to continually process information in the world around us, but our brains just might not be able to handle it. “You have to process information continuously, but you cannot perceive it continuously”, said Herzog.

Of course, that doesn’t translate into reaction time. Your body can react faster than your consciousness can trigger – and these certain reactions may not require us to consciously interpret the information around us.

The result, the authors say, is a two-step model, one in which the consciousness follows a longer unconscious processing time. They compare it to a ship whose captain communicates by radio to the engine room for updates and the engine room which communicates by radio to the captain. Likewise, the brain and body send updates to each other, and these updates occur on demand, rather than continuously or at a set interval.