Epistemic Vigilance in Early Ontogeny: Children's Use of Nonverbal Behavior to Detect Deception.

This study examines the development of children's ability to modulate their trust in verbal testimony as a function of nonverbal behavior. Participants included 83 children (26 four-year-olds, 29 five-year-olds, and 28 six-year-olds) that were tasked with locating a toy hidden in one of two boxes. Before deciding the location, participants watched a video of an adult providing verbal and nonverbal cues about the location of the toy. We hypothesized that older children would display epistemic vigilance, trusting nonverbal information over verbal information when the two conflict. Consistent with our expectations, when sources were consistent, all children trusted the verbal testimony. By contrast, and as predicted, when they were inconsistent, only 6-year-olds distrusted verbal testimony and favored nonverbal cues; 4- and 5-year-olds continued to trust verbal testimony. Thus, 6-year-old children demonstrate an ability to modulate their trust in verbal testimony as a function of nonverbal information. Younger children's inability to do this is not due to their being unaware of non-verbal behavior; indeed, when nonverbal information was offered exclusively, children of all ages used it to find the object.