We investigated facial expressivity in 19 people with
Parkinson's disease (PD; 14 men and 5 women) and 26 healthy
controls (13 men and 13 women). Participants engaged in experimental
situations that were designed to evoke emotional facial expressions,
including watching video clips and holding conversations, and were
asked to pose emotions and imitate nonemotional facial movements.
Expressivity was measured with subjective rating scales, objective
facial measurements (Facial Action Coding System), and self-report
questionnaires. As expected, PD participants showed reduced spontaneous
facial expressivity across experimental situations. PD participants
also had more difficulty than controls posing emotional expressions and
imitating nonemotional facial movements. Despite these difficulties,
however, PD participants' overall level of expressivity was still
tied to emotional experience and social context. (JINS, 2004,
10, 521–535.)