Date Published: June 8, 2018
Publisher: Public Library of Science
Author(s): Benjamin G. Farrar, Ljerka Ostojić, Jacobus P. van Wouwe.
When given privileged information of an object’s true location, adults often overestimate the likelihood that a protagonist holding a false belief will search in the correct location for that object. This type of egocentric bias is often labelled the ‘curse of knowledge’. Interestingly, the magnitude of this bias may be modulated by the social distance between the perspective taker and target. However, this social distance effect has yet to be fully demonstrated when adults reason about false beliefs. Using a continuous false belief task, we investigated i) whether adults were biased by their own knowledge when reasoning about another’s false belief, ii) whether the magnitude of this egocentric bias was modulated by social distance, and iii) whether this social distance effect extended to a heterospecific out-group, namely a dog. To test these hypotheses we conducted three experiments. In Experiment 1 (N = 283), we used an established continuous false belief task, in Experiment 2 (N = 281) we modified this task, and Experiment 3 (N = 744) was a direct replication of Experiment 2. Across these experiments, the curse of knowledge effect was reliably replicated when adults mentalised about an in-group protagonist, and replicated in two of the three studies (Experiments 1 and 3) when adults mentalised about out-group protagonists. In an internal-meta analysis, the curse of knowledge effect was present across all conditions, and there was no effect of social distance. Hence, overall these data are not consistent with the hypothesis that social distance modulates adults’ egocentric biases when reasoning about false beliefs. The finding that egocentric biases of a similar magnitude were observed when adults mentalised about an in-group protagonist and a dog suggests that interpersonal dissimilarity is not in itself sufficient to reduce egocentric bias when reasoning about false beliefs.
Although we possess the ability to attribute mental states to others, this so-called Theory of Mind is often sub-optimal. Both adults and children frequently over-extend their own mental states onto others. Such an egocentric bias is seen when we reason about what others see , feel , know , and believe .
This study tested i) whether adults were biased by their own privileged knowledge when reasoning about another’s false belief, ii) whether the magnitude of this egocentric bias was modulated by social distance and, iii) whether such a social distance effect was still observed with a heterospecific out-group. Across three experiments, participants were biased by their own privileged knowledge when reasoning about the false beliefs of in-group, out-group and heterospecific protagonists. Whilst the data were numerically in-line with the hypothesis that increasing social distance reduces egocentric biases when reasoning about false beliefs, the effect was not significant in i) any of the three studies individually, or ii) overall upon internal meta-analysis. Therefore, the present data do not support the hypothesis that social distance modulates adults’ egocentric biases when reasoning about false beliefs.
Egocentric biases in false belief reasoning were reliably observed across three conceptual replicates of the Birch and Bloom  modified false belief task, when US and UK adults mentalised about in-group, out-group and heterospecific protagonists. These findings are not in-line with the hypothesis that the magnitude of such biases is modulated by social distance [10,11], and suggest inter-agent dissimilarity alone is not sufficient to modulate egocentric biases when reasoning about false beliefs.