Abstract
Facial expressions are one of the most important types of non-verbal communication. Although interpretation of facial expressions is usually robust, studies have shown that both age-related and disease-related factors can influence recognition accuracy. In particular, older people show deficits in recognition of negative expressions. Similarly, patients suffering from Parkinson's disease (PD) also show impairments in recognition of fear, anger, and disgust expressions. These studies so far have only focused on the basic, or "universal" expressions. Here, we were interested in investigating and comparing the effects of age and disease on facial expression processing for a wider range of both emotional and communicational expressions. For our ongoing study we recruited a total of 79 participants: 20 PD patients, 15 age-matched, older healthy controls (HC), and 44 younger healthy controls (HCS). During the experiment, participants were instructed to watch videos of 27 facial expressions performed by 6 different actors and to rate each expression based on 12 evaluative dimensions (arousal, valence, naturalness, politeness, persuasiveness, dynamic, familiarity, empathy, honesty, attractiveness, intelligence, and outgoingness) using a 7-point Likert scale. Ratings were analyzed using within-group and across-group correlations, factor analysis, and item analyses. Overall, we found that ratings of expressions were more different due to age, than due to disease-prevalence: r(PD/HC)=.756 versus r(PD/HCS)=.627, r(HC/HCS)=.640. Three out of six factors in the factor analysis were common for all groups (arousal-dynamic, familiarity-empathy, and naturalness-sincerity), showing common evaluation patterns. Confirming earlier findings of a "positivity effect", valence ratings of negative expressions were higher for both older groups (although valence ratings highly correlated within-group: all r>.919). Similarly, negative expression were perceived as more natural but less persuasive by both older groups. Overall, our results show that age-related factors play a much larger role than PD-related factors in processing of both emotional and communicational facial expressions.
