Reading and the Brain

As whole language theorists suggested in the 1970s, we do not selectively read print, skip over words, or recognize words by sampling a few letters of the print, even though we may not be aware of it. Reading is achieved by processing words one letter at a time.

If you watch the eyes of a person scanning text at a normal rate, the eye seems to be ahead of the voice when we read aloud. The precision eye-movement research of scientists such as Rayner and Pollatsek (1989) at the Massachusetts Institute of Technology showed in many experiments over 20 years that the reading eye fixates on most content words (especially nouns and verbs) in a rapid series of stops and jumps called fixations and saccades. When fixated, the eye rests for about .25 seconds (250 milliseconds) on a content word and takes in a span of about seven to nine letters to the right of the fixation and three to four letters to the left before it jumps over to the next fixation point. More letters are processed to the right of the fixation if the eye is scanning from left to right. The opposite would be true for reading a language that is scanned from right to left, such as Hebrew or Arabic.

Saccades: what are they?

We constantly produce quick eye movements known as saccades whenever we visually explore a space, look for an object, or, of course, read. Although saccades on the faster end of this spectrum are referred to be express saccades, these saccades normally last between 20 and 200 ms.

Our eyes stay motionless for 200–300 ms in between these saccades; this is called a fixatio. The word “still” is a little ambiguous here because our eyes frequently continue to move due to optokinetic nystagmus, which helps the brain process visual information.

The typical saccade size is seven to nine letter spaces, though this may obviously vary depending on the font type and text size. It should come as no surprise that as the material gets harder to read, this number drops.

For English speakers and readers, reading involves more than just saccades from left to right; it also involves eye movements from right to left about 15–25% of the time. If the text demands a lot of mental work (i.e., as cognitive load increases), the percentage of right-to-left eye saccades increases

What are fixations?

Fixation is the ability to aim the eyes to a particular spot accurately. Static fixation is the ability to focus on a stationary object when reading a word or working a math problem. Fixation occurs monocularly or binocularly.

Fixations are–

• Duration

  Fixations typically last around 250 milliseconds. 

   

   
• Purpose

  Fixations allow the reader to process information from the word being fixated, as well as some information from the word that comes next. 

   

   
• Eye movements

  Fixations are separated by saccades, which are quick, accurate eye movements that move the eyes across the page. 

   

   
• Factors that affect fixations

  The number of words a reader can take in during a fixation is affected by their vocabulary and how familiar they are with the topic