Chronostasis

Chronostasis is an optical illusion in which time momentarily seems to stop after a person suddenly shifts their attention from one object or task to another. This effect is also known as the stopped-clock illusion because it is most often observed when a person suddenly glances at a clock and notices that the second hand is seemingly “frozen” for a short time. The illusion is caused by a temporary disconnect between the eyes and the brain. As a person quickly moves their eyes from one source of information to another, the brain enters a brief period where it cannot process the new information fast enough. As a result, the section of the brain that processes visual information briefly shuts down. To compensate for this lack of information, the brain fills in the gap with a previous image, giving the illusion that time has stopped moving.

Background

The human brain acts as the body’s command center, receiving and processing information from the sensory organs and sending out signals through the nerves to control a range of bodily functions. The structure of the brain is divided into three main sections, with each section responsible for a specific range of functions. The brain stem is a small section at the base of the brain that connects the upper levels of the brain to the spinal cord. This section is responsible for bodily functions, such as heartbeat, breathing, and swallowing. The cerebellum is a section at the back of the brain that controls balance, coordination, and muscle control.

The large, top part of the brain is the cerebrum, which controls a multitude of functions from thinking to sensory perceptions to experiencing emotions. The cerebrum is divided into two hemispheres, with each hemisphere further divided into four sections called lobes. Each of the lobes—frontal, parietal, temporal, and occipital—is responsible for controlling specific bodily processes. Each lobe controls specific functions. For example, the frontal lobe controls personality, decision-making and reasoning, while the temporal lobe controls memory and speech, and the parietal lobe processes touch and taste.

The occipital lobe is located near the back of the cerebrum and is responsible for processing and interpreting visual information. When visual information is perceived by the retinas in the eyes, it travels to the thalamus, a relay system located above the brain stem in the center of the brain. From there, it is sent to the visual cortex in the occipital lobe, where it is processed and interpreted. The visual cortex then sends the information to other regions of the brain to be further analyzed and used according to that area’s function. Because the process of visualization is highly specialized, the brain is able to receive, interpret, and disseminate visual information very quickly, with little, if any, conscious effort.

Overview

Although humans perceive the outside world and the passage of time as being instantaneous and an unbroken chain, the brain actually gets the information from the senses a small fraction of a second after they are received. However, the brain seeks to convince the body that the world and the information it receives are in sync, so it creates a number of illusions when it needs to cover up the discrepancy.

When humans move their eyes back and forth very quickly, it creates a temporary break in the process of sending information from the eyes to the visual cortex. This phenomenon creates a blurry visual field known as saccadic suppression and a distorted perception of spatial recognition called saccadic compression. The same effect occurs when a person perceives the outside world from a moving vehicle, such as a car or train.

Chronostasis—from the Greek words chrono (time) and stasis (standing still)—is an optical illusion created by the disconnect that occurs during saccadic eye movement. The illusion makes it seem like time has stopped for a brief moment as a person quickly shifts their gaze between visual subjects. The most well-known example of this phenomenon is called the stopped-clock illusion. In this example, a person is performing a task such as reading a book when they suddenly look away to check the time. To them, the second hand on the clock seems to be stuck in place for a bit before it starts moving again.

This illusion results from the interruption of the flow of information from the eyes to the visual cortex. As the person reads, the visual cortex has been processing the words on the page and sending that information to the parts of the brain responsible for comprehension, emotions, etc. When the visual information suddenly changes, the visual cortex momentarily shuts down. The eyes and the brain are receiving the new visual information, but the visual cortex stops accepting it for a moment. Once the eye movement has stopped, the visual cortex starts working normally again.

However, the brief shutdown causes a momentary lapse in processed visual information. The brain tries to hide this lapse by performing a little trickery. The brain takes the visual information it received the second the eyes stopped moving, copies it, and uses it to fill in the gap. This brief mental snapshot of the information is technically perceived after it has already occurred. After a brief moment, the brain catches up with the present and synchs its visual processing system.

The result of the illusion is that time seems to stop for a moment and then start again. For example, a person suddenly looking up from a book to a clock would at first perceive the second hand as being frozen in place as the brain “repeats” the image. After a moment, the clock would begin moving normally again as the person’s brain “catches up” with the outside world.

Bibliography

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