It has long been assumed that babies are fascinated by people’s faces. But how interesting, exactly, are human faces to infants? Compared to what? Are they equally interesting to all healthy infants? Of course, infants are not only interest in faces, but also toys, animals, etc. Are faces more interesting even than these other things?
As part of our MESA project, we addressed these questions by showing infants two new faces every month from 4 to 10 months. For comparison, we also showed them two new toys each month. Infants looked at one face (or toy) repeatedly until they stopped looking, then were shown the other face (or toy). This tells us how fast infants lost interest in one stimulus, and their interest was “re-piqued” by another stimulus of that kind.
Most infants were consistently interested in the faces. They were equally interested in toys only if they saw the toys first, and then the faces. If they saw the faces first, they showed less interest in the toys.
One interpretation is that faces were somewhat more interesting than toys, but not overwhelmingly so. For example imagine you like apples but love pears. If someone gives you an apple you will happily eat it; if they then give you a pear you will probably eat it happily too even though you are somewhat sated. However, if they give you a pear first and you eat it, when they then give you an apple, you will probably not eat it with as much enthusiasm, partly because you are somewhat sated and because it’s a bit of a “let down” to go from something you really like to something you only kind of like.
You can read the findings in more detail here.
We also found that infants were not terribly consistent from month to month in their relative interest in faces or toys. This is a topic we want to investigate further.