Give Now

A Moment of Science

How We Read

The part of our eyes we use to see fine detail, and to read, is actually very limited: an angle of five degrees at the center of our field of vision.

A skilled reader’s eyes move four or five times each second.

Why do our eyes make short, rapid movements as we read instead of scanning the page continuously?

The last time you saw someone reading a book, you may have noticed their eyes didn’t follow the line of text smoothly, but instead seemed to make little jumps across the page. These movements are called saccades, and we make them thanks to the anatomy of our eyes.

Photons

When we open a book, the process of reading begins with photons, or particles of light. Photons are reflected off of the page and enter our eyes.

At the back of our eyes are our retinas, which is where we find the light receptors, rods and cones, that translate particles of light into nerve signals, creating the images we see. The rods allow us to see in dim lighting, while the cones respond to bright light and allow us to see color and fine detail.

Fovea

But these light receptors are not evenly distributed across our retinas. The part of our eyes we use to see fine detail, and to read, is actually very limited: an angle of five degrees at the center of our field of vision.

This part of the eye, at the center of the retina, is called the fovea, from the Latin word for pit, and it is the most dense with cones.

According to scientists, the brain also adjusts the distance for each saccade according to the size of the print, so that the number of letters we take in with each movement remains constant: seven to nine. (Also according to scientists, learning how to read changes the structure of your brain.)

Because of this, a skilled reader’s eyes move four or five times each second, apprehending as they go.

Thank you to T. Rowan Candy of Indiana University for reviewing this episode’s script!

Sources And Further Reading:

Stay Connected

What is RSS? RSS makes it possible to subscribe to a website's updates instead of visiting it by delivering new posts to your RSS reader automatically. Choose to receive some or all of the updates from A Moment of Science:

Support for Indiana Public Media Comes From

About A Moment of Science

Search A Moment of Science