Show or tell: testimony is sufficient to induce the curse of knowledge in three- and four-year-olds.

Because much of what children learn extends beyond their first-hand experience, they are reliant upon the testimony of others to acquire information about aspects of the world they have not experienced directly. Here we asked whether testimony alone would be sufficient to induce cognitive biases in knowledge attribution that have been observed when children acquire information through direct observation. A total of 80 three- and four-year-old children were tested on a "curse of knowledge" task to assess their inability to override their own knowledge when asked to assess the knowledge of a nave other. In the present study, we tested children's ability to override knowledge gained through testimony rather than knowledge gained through visual experience. Testimony alone was sufficient to induce the curse of knowledge in three- and four-year-olds. Knowledge obtained through the testimony of others is apparently subject to some of the same cognitive biases that are present when children learn through observation.