Do we see the features of a bizarre face first and then acknowledge its oddity or do both processes somehow occur simultaneously? Does the bizarreness of the face influence how we perceive the facial features to begin with?

To address these questions, it would be necessary to analyze the response of our brain to identical visual stimuli with varying emotional attributes, such as unpleasantness or bizarreness. Since it is not trivial to change the emotional load of a stimulus without altering its visual appearance dramatically, a definitive answer to these questions has remained elusive.

Now an Israeli research team has devised an experimental protocol that overcomes this problem. Their findings, reported in today's issue of Neuron, shed some light on the interaction between emotion and visual perception.

In their study, Hendler and colleagues used the following classical visual illusion: by simply inverting the eyes and the mouth in a face one can dramatically change its emotional impact. The resulting face looks bizarre but its visual features remain largely unchanged.

The results suggest that the emotional load of a stimulus does not affect the way we perceive it but does have an effect on how we become used to it if we see it many times.

Imaging of the brains of subjects looking at these faces showed that the amygdala, a brain region implicated in emotional response, may play a role in this emotion-dependent adaptation.

[Contact: Talma Hendler]

20-Nov-2001