Valence and arousal: a comparison of two sets of emotional facial expressions.

Facial expressions are often used in emotion research. Although they may differ in several relevant features such as the intensity of the facial expressions, the picture sets have not been compared systematically. Because the intensity of expressions is thought to determine the level of emotional arousal induced by the stimulus, the first aim of this study was to test whether 2 frequently used sets of emotional facial expressions induce different levels of perceived arousal. Furthermore, we tested whether the sex of the actor modulates arousal ratings. Participants viewed facial expressions from the NimStim set (more intense expressions) and the Karolinska Directed Emotional Faces set (less intense expressions). Female expressions from the Karolinska Directed Emotional Faces but male expressions from the NimStim set were rated as more emotionally arousing. We conclude that less intense female expressions but more intense male expressions may be more potent in inducing emotional responses. This study may encourage researchers to further compare the properties of picture sets.