The Illusion of “Now”

Without the brain’s ability to project information into the future, fast-paced activities like playing tennis would be impossible.

Source: Andrew Heald | Unslpash

The brain is extraordinary and has been described as the most complex structure in the known universe (Pang, 2023). We are constantly bombarded with an abundance of information from the complex and ever-changing world around us. One of the incredible feats of the brain is to make sense of this tangle of sensory information and to create a stable and coherent way we perceive the world.

Even a seemingly simple action, like reaching out to grab a cup of coffee in front of us, is incredibly complex. The lenses in our eyes refract light and create an upside-down image on our retina. There is a common belief that our brain simply rotates the image our eyes receive but the reality is far more complex: The brain takes in many different cues to decode which way is up, including by correcting for head movements using feedback signals from the vestibular system in our ears that help us balance (Rogers-Ramachandran and Ramachandran, 2008). These are only some of the many complications the brain must deal with—most of our eyes receive information in a very low resolution that is quite blurry, like looking through frosted glass (Johnson and Finn, 2017). Only a small area accounting for about 1 percent of the visual field, called the fovea, offers focused and high-resolution vision (Johnson and Finn, 2017). There is also a blind spot in our visual field where we don’t receive any sensory information (where the nerve fibers exit the retina) and the nose is blocking a good chunk of our visual field (Payne, 2013). We use rapid eye movements called saccades to scan our environment (Gegenfurtner, 2016) but even with all that information, the brain has to construct a stable and coherent image. It gets even more complicated to accurately judge the distance of the coffee cup or identify the cup as a three-dimensional object distinct from the background (or knowing that it is a cup). Even without going into all these details, it is clear that perception is neither simple nor straightforward. We cannot simply see what is out there; the brain has to actively construct a picture of what it thinks is around us based on limited and often fuzzy information while filtering out the overabundance of irrelevant information. It’s like trying to build a model of a constantly changing world. All of this takes an incredible amount of processing power and does not happen instantly.

Overcoming delays

It takes the brain time to process information before we perceive it. This means that the information we receive is always outdated. The exact time is difficult to measure but is likely around 80-100 milliseconds (Allison and colleagues, 1994; Koevoet and colleagues, 2023). This may not seem like much but can be a problem in many situations where things happen quickly like driving, or in sports (Koevoet and colleagues, 2023). Professional tennis players reach serve speeds of over 200 kilometers per hour or close to 130 miles per hour (Yandell, 2005). At this speed, a delay of 100 milliseconds would result in misjudging the position of the ball by over five meters!

To overcome this problem, the brain uses the outdated information it has and projects it into the future. What we ultimately perceive is a construction that shows the brain’s best guess of what will happen in the future based on delayed information from the past, thereby creating the illusion of perceiving what is happening right now.

Processing incoming visual information takes time and creates a delay. Our brains use this outdated information and project it forward, creating an illusion of “now” based on the best available information.

Source: Damian Pang (incorporating images from Alex Viau | Unsplash and OpenClipart-Vectors | Pixabay).

Constructing images

Perception, then, is based on what our brains construct rather than the raw information our senses pick up. That does not mean that perception is random or entirely removed from our senses: Our brain is trying extremely hard to provide the best possible interpretation of the world around us. To extract meaningful information, we need to filter out all the noise and prioritise what is important. Most of this happens without conscious awareness: Sensory data is briefly retained in a buffer store that operates subliminally, where it is evaluated (Pang and Elntib, 2021; 2023). Only some of the information that was sensed and briefly stored is later perceived consciously (Pang and Elntib, 2021; 2023). Our vision is not like a camera that records all the light that falls on the digital sensor. Instead, the very imperfect sensory input is decoded, deconstructed, and then reassembled into a stable and coherent picture (Manassi and Whitney, 2022).

When is now?

Einstein’s theory of special relativity suggests that this depends on the frame of reference that is used. Meanwhile, neuroscience shows us that we cannot perceive anything that is now because the brain takes time to process information and therefore, anything we perceive is necessarily based on information from the past. However, to navigate the world and experience things in real time, the brain projects information forward, giving us its best guess of what things will be like in the future. The now we perceive moment to moment is an illusion, a guess of what the future will be like based on the past. This now may not always perfectly match up to our external reality, but it is the entirety of our experience. It is our reality and a very close match to how the external reality was just a moment ago.

Facebook image: dotshock/Shutterstock