The mystery of how we read a sentence has been
unlocked by scientists.
Previously, researchers thought that, when
reading, both eyes focused on the same letter of a word. But
a UK team has found this is not always the case.
In fact, almost 50% of the time, each of our
eyes locks on to different letters simultaneously.
At the BA Festival of Science in York, the
researchers also revealed that our brain can fuse two separate
images to obtain a clear view of a page.
Sophisticated eye-tracking equipment allowed
the team to pinpoint which letter a volunteer's eyes focused
on, when reading 14-point font from one metre away.
Rather than the eyes moving smoothly over text,
they make small jerky movements, focusing on a particular word
for an instant and then moving along the sentence. Periods when
the eyes are still are called fixations.
Crossed eyes
Professor Simon Liversedge, from the University
of Southampton, said: "We found that in a very substantial number
of fixations that people make when they read, they aren't looking
at the same letter."
Instead, the eyes often focussed on different
letters in the same word, about two characters apart, he said.
"They could be uncrossed, in the sense that
the two lines of sight are not crossed when you look at a word,
or alternatively the two lines of sight may be crossed," he
added.
The team's results demonstrated that both eyes
lock on to the same letter 53% of the time; for 39% of the time
they see different letters with uncrossed eyes; and for 8% of
the time the eyes are crossing to focus on different letters.
A follow-up experiment with the eye-tracking
equipment showed that we only see one clear image when reading
because our brain fuses the different images from our eyes together.
The tests showed that we use the information
from both eyes, rather than our brain suppressing one image
and only processing the other.
Professor Liversedge said: "A comprehensive
understanding of the psychological processes underlying reading
is vital if we are to develop better methods of teaching children
to read and offer remedial treatments for those with reading
disorders such as dyslexia."
