The knowledge ("true belief") error in 4- to 6-year-old children: When are agents aware of what they have in view?

The standard view on explicit theory of mind development holds that children around the age of 4 years start to ascribe beliefs to themselves and others, typically tested with false belief (FB) tasks. The present study (N = 95, 53 female, 41 male, Austrian, 41 to 80 months) systematically investigated the puzzling phenomenon that FB achievers (FB+) fail knowledge (often subsumed under "true belief") tasks: Despite the story protagonist witnessing the displacement of an object these children predict that the protagonist will look for it in its original location. We replicate this result in Experiment 1. Interestingly, some of our children indicated uncertainty about the protagonist's awareness of the relevant event. Thus, in Experiment 2 a new active watching condition was designed to help children understand that the protagonist attended to the critical event. This practically eradicated the knowledge error. Experiment 3 successfully replicated these results. Implications for existing explanations, perceptual access reasoning (PAR, Fabricius, Boyer, Weimer, & Carroll, 2010) and pragmatic difficulties (Oktay-Gür & Rakoczy, 2017) are discussed.