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Neglect syndrome – ignoring half the world

By Eric Brindeau,

Right Hand Left Hand by Chris McManus is a fascinating book about handedness, from its history to what might be the reason why about 90% of us are right-handed. His book comes highly recommended by The Naked Scientist, aka Chris Smith, who has a weekly talk show radio slot on 702, answering questions related to science and how the world works. Questions related to handedness often come up.

Throughout history, scientists have studied brain-damaged patients to try to figure out how the brain functions and determine what part of the brain controls which parts of our bodies. For example, does the left or right hand side of the brain control language? Mostly the left hemisphere.

Visual neglect is a condition resulting from right-hemisphere damage that could result from a stroke or other form of damage. Patients with neglect ignore half the world, typically the left half, like drawing only the one half of objects.

These drawings are missing their left halves, which is a result of damage to the right parietal lobe. Source A.C. Brown Physiology & Neuroscience

What does neglect have to do with website design?

Just as some brain-damaged patients ignore the left half of space, normal people over-exaggerate it – a condition called pseudoneglect. For most of us, the left half of space attracts more attention than the right – so we are more likely to bump into things on our right, for example.

McManus gives the following simple demonstration: decide if the top or bottom bar looks darker in the figure below?

Does the bar at the top or the bottom look darker?

The two bars are actually identical. According to McManus, about three-quarters of people say the top bar looks darker; we over-exaggerate the left of space.

Does eye-tracking show pseudoneglect?

Website eye-tracking studies show something similar: we tend to ignore what is on the right of the screen, focusing more intensely on the left – known as the F-shaped pattern. This is expected in cultures that read from left to right. But could this also be because of pseudoneglect? That’s an interesting possibility, not one I’ve come across in research literature. Here’s an example of the F-shaped reading pattern heat maps produced by eye-tracking software that is typical of our Web use:

F-Shaped Pattern For Reading Web Content, Jakob Nielsen