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Against expectations, no evidence that toddlers with older siblings have superior Theory of Mind

02 August 2017

When young kids play together there’s often a lot of negotiation involved: “That’s my bunny”, “No, it’s mine”, “OK, you have it”. There’s talk of emotion: “Why are you crying?”, “You took my bunny”. And role-play: “You be baddie”, “No, I’m super-bunny”. Perhaps it shouldn’t be too surprising then that a recent meta-analysis found that young kids, aged 3 to 7, with more siblings have superior Theory of Mind (understanding other people’s mental states and perspectives – an important ability that benefits social and academic performance at school).

A new study in Journal of Cognition and Development asks whether the sibling advantage begins as early as toddlerhood, and whether it matters if a toddler’s sibling is older or younger. In fact, against expectations, toddlers with an older sibling showed no Theory of Mind advantage compared with only children, and toddlers with a younger sibling actually performed worse.

Élizabel Leblanc and her colleagues tested 227 two-year-olds (113 boys) on two age-appropriate Theory of Mind tasks. One was focused on perspective-taking and required the toddlers to show their mother a toy and in the process deal with various challenges, such the fact she had her eyes closed or was facing the wrong way. The other task pertained to diverging interests: the toddlers had to choose a book to give the researcher, either a children’s book for which she’d previously expressed dislike or an adult book.

Read more on our Research Digest blog.


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