@article {310299,
	title = {Meta-analysis of theory-of-mind development: the truth about false belief.},
	journal = {Child Dev},
	volume = {72},
	year = {2001},
	month = {2001 May-Jun},
	pages = {655-84},
	abstract = {<p>Research on theory of mind increasingly encompasses apparently contradictory findings. In particular, in initial studies, older preschoolers consistently passed false-belief tasks-a so-called "definitive" test of mental-state understanding-whereas younger children systematically erred. More recent studies, however, have found evidence of false-belief understanding in 3-year-olds or have demonstrated conditions that improve children{\textquoteright}s performance. A meta-analysis was conducted (N = 178 separate studies) to address the empirical inconsistencies and theoretical controversies. When organized into a systematic set of factors that vary across studies, false-belief results cluster systematically with the exception of only a few outliers. A combined model that included age, country of origin, and four task factors (e.g., whether the task objects were transformed in order to deceive the protagonist or not) yielded a multiple R of .74 and an R2 of .55; thus, the model accounts for 55\% of the variance in false-belief performance. Moreover, false-belief performance showed a consistent developmental pattern, even across various countries and various task manipulations: preschoolers went from below-chance performance to above-chance performance. The findings are inconsistent with early competence proposals that claim that developmental changes are due to tasks artifacts, and thus disappear in simpler, revised false-belief tasks; and are, instead, consistent with theoretical accounts that propose that understanding of belief, and, relatedly, understanding of mind, exhibit genuine conceptual change in the preschool years.</p>
},
	keywords = {Child, Child, Preschool, Concept Formation, Female, Humans, Male, Perceptual Distortion, Personality development, Self Concept, Social perception, Visual perception},
	issn = {0009-3920},
	author = {Wellman, H M and Cross, D and Watson, J}
}
