Expression and communication of doubt/uncertainty through facial expression

There is a wide debate on the mental state of doubt/uncertainty; one wonders whether it is a predominantly cognitive or emotional state of mind and whether typical facial expressions communicate doubt/uncertainty. To this purpose, through a role playing procedure, a large sample of expressions were collected and afterwards evaluated through a combination of encoding and decoding procedures, including also FACS (Facial Action Coding System) analysis. The results have partially confirmed our hypothesis, identifying two typical facial expressions of doubt/uncertainty, which share the same facial actions in the inferior part of the face and show differential facial actions in the upper face.