Infants' performance in spontaneous-response false belief tasks: A review and meta-analysis.

Evidence obtained with new experimental paradigms has renewed the debate on the development of theory of mind in general and false belief ascription in particular. Namely, several studies contend to prove that infants already have the capacity to attribute false beliefs. The aim of the current meta-analysis is to review and summarize the empirical evidence about spontaneous-response false belief tasks in infants younger than 2 years old. Fifty-six false belief conditions using the violation-of-expectation, the anticipatory looking and interactive paradigms were included in this meta-analysis, including 1469 infants. The role of several moderators was examined, following Wellman et al.ös meta-analysis (2001). Results show that correct performance on spontaneous-response false belief tasks was about 1.76 times more likely than incorrect performance (β = 0.57, 95% CI 0.33; 0.80, p <  .0001). Mediator analyses revealed that (i) year of publication had a significant influence on performance, reducing the average log odds of successful performance (β = -0.11, 95% CI: -0.16; -0.06, p < .0001); and (ii) correct performance was more likely than incorrect performance when the task was conducted in the violation-of-expectation paradigm (β = 0.75, 95% CI: 0.25; 1.26, p =  .003). However, heterogeneity was high across the studies and the funnel plot revealed an asymmetric distribution suggesting that studies with small effect sizes were not published. These results cast doubt on the alleged robustness of the phenomenon: its effect size decreases as time passes, it seems to depend on the type of paradigm employed, and the variance across studies is not well understood yet.