How the brain reacts to faces

Can actors like Angelina Jolie and Halle Berry help you decipher how your brain reacts to ambiguous faces? Yes, if their images are intermingled.

Morphing such celebrity images together, scientists created an ambiguous face that participants were asked to identify.

The findings reveal that individual neurons in the human brain are triggered by the subject's conscious perception rather than by the visual stimulus.

"For example, a neuron originally firing to Whoopi Goldberg is fired to a morph image between Goldberg and Bob Marley only when the subject identified the morphed image as Goldberg and remained silent when the subject said the very same image was Marley," explained professor Rodrigo Quian Quiroga, director of the centre for systems neuroscience and head of bioengineering at the University of Leicester.

We are constantly bombarded with noisy and ambiguous sensory information and our brain is constantly making decisions based on such limited data.

"We indeed see the face of a friend rather than the combination of visual features which compose the person's face. The neurons we report in this article fire exactly to this - to the subjective perception by the subjects and not to the features of the faces they were seeing," Quiroga pointed out.

Researchers concluded that neurons fire in line with conscious recognition of images rather than the actual images seen.

Furthermore, in most cases, the neuron's responses to morphed pictures were the same as when they were shown without morphing.

"The result also supports the view that these neurons are play a key role in the formation of memory," researchers concluded in a paper published in the journal Neuron.