Thomas said that slower or noisier neuron signals to and from the fusiform gyrus could justify some cases of face blindness.

In celebrity face recognition tests, for example where subjects were asked to identify a hairless Elvis Presley, the brain connections predicted the scores of people with prosopagnosia, as well as controls.

Thus, Thomas deduced that prosopagnosia is a matter of degree.

Now, a German team has found that face blindness is hereditary and is currently searching for genes linked to the condition.

Brad Duchaine, a cognitive neuroscientist at University College London claimed that the hunt might not be so clear-cut.

Duchaine said the new findings may provide explanation for some cases of prosopagnosia, but at least six brain regions are involved in face processing and various injuries or biological changes could affect how they work.

"There are a lot of ways that face processing can go wrong," he said.