Sibling Influences on Theory of Mind

Sibling Influences on Theory of Mind

By Amy Cleator, Provisional Psychologist

Theory of Mind (ToM) can be defined as the ability to understand that people (including self and others) have thoughts, beliefs, desires and emotions, which influence and explain actions and behaviours.  In typically developing children, advances in ToM occur between the ages of 3 and 5 years, whereas ToM is often delayed in children with ASC.  A number of studies have found that for neuro-typical children, having an older brother or sister helps to build language development and ToM, through social and conversational interactions and imaginative play.

O’Brien, Slaughter, and Peterson (2011), were interested in whether the positive influence of older siblings on ToM was relevant to children with ASC.  The results of the study suggested that children with ASC who had older siblings, actually had slower ToM development, than those with younger siblings.

Why is this the case?

The authors suggested that:

  • First born children with ASC tend to receive more playful and conversational interactions with their parents, whereas later born siblings, or those in larger families, have to compete for their parent’s time and energy.
  • Older siblings may overcompensate for their younger siblings social difficulties in the home by being overprotective in a number of ways, such as:
  • giving them easier tasks to complete,
  • taking on more responsibility,
  • avoiding typical sibling interactions (such as teasing, arguing, and joking),
  • initiating and maintaining conversations and interactions

This limits opportunity for the challenges and opportunities that can assist ToM development.

In comparison, the younger siblings of children with ASC:

  • are typically less aware of their siblings differences,
  • and interact more spontaneously and with more equality (e.g., pretend play, engaging in conflict)

The authors suggest the best way for parents to help develop greater ToM in their children, is to promote sibling equality, and encourage their children to engage in mutual play, humour, open communication and some good-natured sibling bickering (sorry parents!).

Author: Amy Cleator, Provisional Psychologist


O’Brien, K., Slaughter, V., and Peterson, C. (2011). Sibling influences on theory of mind development for children with ASD. Journal of Child Psychology and Psychiatry, 52, 713-719.