Between the year and a half and two years is when the children realize that the little person that appears in the mirror and in the photos are themselves.
Although they love to look at each other and make faces in the mirror since childhood, it is only at that age when they begin to have a sense of their body in space and are able to recognize the image of themselves.
An American psychologist studied the reaction of a group of children in front of the mirror by painting a red spot on their nose. Before 15 months, none was recognized, between 16 and 18 months, 24% did so and between 19 and 24 months, 76%.
Now, if they were not seen in a mirror would they be equally able to recognize each other? Yes, the mirror is not indispensable. The image of themselves is formed through affective development, that is, it is the parents, rather than the mirror itself, who help form their "self." They are reflected in their reactions, they become aware of their body as we caress them and little by little they are self-aware of their body. They reinforce their feeling of "me."
Therefore, even if they do not look in a mirror, they would still recognize each other.
Our attitude towards them has a determining effect, it is their conception. To give you an idea, there are studies that reveal that abused children, recognizing themselves in the mirror, are indifferent or have negative reactions.
