The Australian study has found mothers perceive their youngest children as the smallest of their siblings – regardless of whether this is true or not.
This ‘baby illusion’ seems to apply regardless of how many children the mother has, the study, published this week in the journal Current Biology, shows.
Researchers surveyed more than 700 mothers about their youngest children, asking them whether they remembered a sudden shift in their youngest child’s measurements immediately following the birth of their newest baby.
More than 70 per cent of mothers believed they had. The illusion of sudden growth was more pronounced in the mothers minds when discussing the former ‘baby’ of the family – mothers where less likely to report a significant difference in other siblings.
Interestingly, mothers where also found to underestimate their youngest child’s height by an average 7.5 cm – yet at the same time accurately judged the height of their older children.
The study’s authors believe the phenomenon is an ‘adaptive mechanism’ – a biological instinct to nurture and protect the most vulnerable of her offspring.
It is not just because the older child looks bigger compared to the baby, researchers argued. It is due to this ‘baby illusion; where parents viewed the youngest child, at that time, as smaller than he or she really was.
But the ‘baby illusion’ is broken once a new baby arrives and parents begin to see he or she as they really are, the study suggests.
“Our research potentially explains why the ‘baby of the family’ never outgrows that label. To the parents, the baby of the family may always be ‘the baby’,” explained the study’s lead researcher Jordy Kaufman, of Swinburne University of Technology.