I just asked one of my colleagues who has just had a baby and has lots of baby books. She says that yes, it is true and that they don’t see things in 3D until they are about 3 months old either. Neither of us knows why though.
That’s really interesting, and I don’t know the answer. But it’s quite possible, because seeing in colour is due to some specialised receptors in your eye. Maybe new born babies don’t have those receptors yet.
When babies are born, they can only see in black and white, and shades of gray. It is only after the first weeks that they begin to see in colour. Also, it takes them longer to develop blue and violet colour vision, because that light is of a shorter wavelength, and fewer colour receptors exist for light of that colour. A number of factors tell us that the vision is not the same as ours.
Firstly, the brain is not used to interpreting the huge amount of visual signals it is receiving, and so does not process it as in an adults brain. Second, they haven’t yet learned to control the focussing of light via the lens, and the nerve cells in the retina (the light sensing part at the back of the eye) are not yet matured.
In terms of why they only see in black and white straight after birth – I suppose that there is no reason why human babies need to be born with 100 % decent vision straight away, unlike, say, crocodiles, which must fend for themselves from birth. Human young are well cared for by their parents, and are not born into situations of immediate danger as our ancestors young may have, for some time, so there has been no evolutionary pressure towards young which have better vision, sooner.
I’m not sure, but I’d be surprised if that is true. We can see colours because of the light-detecting molecules attached to the back of our retina, and I have no reason for believing that babies would be any different.