Facial expressions consistent with what is being said promote credibility. Facial expressions that are inappropriate for the situation decrease effectiveness. For example, smiling when talking about the death of someone generally is viewed as inappropriate. A witness who smiles in this situation, therefore, is likely to be less effective than one who does not smile. Eye contact enhances credibility.
Difficulties arise when witnesses avert their eyes when giving important answers.
Inconsistency between nonverbal communication and the content of what is being said detracts from the witnesses' effectiveness. When witnesses express anger or sadness verbally but project a calm demeanor, credibility is lessened. In addition, if the emotion is expressed verbally while the onset of the supporting body movements is delayed, then credibility also is reduced. For maximum effectiveness, verbal and nonverbal communication should be consistent. Prepare witnesses for the experience of examination.