Categorical effects in the perception of facial expressions; MARIE - A simple and discriminating clinical tool

Certain stimuli varying along a physical continuum are perceived as discrete categories. This defines so-called "categorical perception", where the subject is very sensitive to between-category differences but largely insensitive to within-category differences. This is well known for some unidimensional stimuli, like colours and phonemes. Categorical perception was recently evidenced for multidimensional stimuli, namely facial identity and facial emotional expressions. The present study describes M.A.R.I.E., a simplified and easy-to-use clinical tool, which reveals categorical perception of emotional facial expressions. An example of its potential is given by analyzing the effect of aging upon such categorical perception of expressions.