Babies love mirrors BUT research shows that babies typically don’t recognise that it’s them they see in the mirror until 18-24 months of age.
The way we test this is with a “rouge” or “sticker” test. We surreptitiously place a sticker in the infant’s hair or mark their face with lipstick. The baby is placed in front of a mirror & we observe their reaction. Before 18 months, most babies smile and play with the ‘other baby’ in the mirror.
Closer to 18 months things start to change: some babies look behind the mirror to see where the ‘other baby’ is hiding. Others are confused by what they see but don’t know why. Between 18,-24 months of age, most infants see the sticker and try to remove it. This is when we know for sure they understand that the ‘other baby’ in the mirror is them!
Mirror self-recognition is a pivotal skill, providing the first clear evidence of an understanding of self. An infant’s developing self-awareness means they have begun the representational processes that distinguish between self and other.
The ability to recognise ourselves in a mirror is suggested to be a developmental precursor to a ‘theory of mind’ – the ability to attribute mental states to others. This is the understanding that you and I have different thoughts, feelings and beliefs. Mirror self-recognition is crucial skill that lays the foundation for so much of what it is to be human.
Without a concept of self & an appreciation that ‘my’-self is different to ‘your’-self, things like language, humour, deception, embarrassment & empathy are impossible. A concept of self, I'm ME & you're YOU, is what allows us to truly connect with one another.
References: Gallup (1998); Nielsen & Dissanyake (2004); Lewis (1995)