Can you tell if these two faces are the same or different?
How about these?
If you’re like most adults, it will be easier for you to identify different adult faces compared to the infant faces in the second example, and even the small children’s faces in the third example.
This makes some sense, since most people don’t spend much time around a wide variety of infants. Even a new parent typically only sees one or two infants at a time. The infants you see out in public are usually wrapped up and often are difficult to see. Most of us see more children than babies, but unless you’re a preschool teacher or a parent, you still probably don’t spend as much time with kids as you do with adults.
It’s possible that this “other age effect” is similar to the “other race effect” we’ve discussed here before: If you live in a homogenous community, whether it’s all White people or all adults, it may be that you’re eventually going to become better at distinguishing between individual members of your community than you are to recognize others, whether they are Black people or babies.
Studies of the other race effect have found that it’s not automatic: if an Asian person lives for a long time among White people, she’ll be just as able to distinguish between White people as White people are. But studies about different-aged individuals have been inconclusive.
A team led by Dana Keufner showed 31 Italian university students a photo of an infant for 1 second at a time. The photo disappeared for a half-second, then was replaced by two photos, one of which was the baby they had previously seen. Their task was to identify the previously-seen face as quickly as possible. They repeated the task with upside-down babies, and finally with right-side-up and upside-down adult faces (the order was randomized). In all they saw 48 different faces in each category. Here are the results:
As you can see, they were significantly more accurate in identifying upright adult faces compared to infants. When the faces were upside-down, there was no difference in accuracy between adult and infant faces, or upright infant faces. There was a similar difference in reaction times (slower for upside-down and infant faces). This suggests that adults use a different mental process for identifying infant faces and adult faces. Inverting the faces equalizes the task. The researchers suggest that upright adult faces are being identified using a configural strategy, which has been well-documented in other studies. The inverted faces, as well as the infant faces, are recognized using a different, piecemeal strategy.
Next the researchers repeated the experiment with 3- to 4-year-old faces. Here are those results:
The results aren’t as dramatic, but they show a similar pattern. Adults are still significantly better at identifying adult faces compared to 3- and 4-year-olds.
So what about people who spend more time around children? Does this reduce the effect? Kuefner’s team repeated the experiment, using preschool teachers who spent at least 30 hours per week with small children. Here are the results:
This time there was no significant difference in accuracy between recognition of upright children’s faces and adult faces. So just spending more time around kids improves your ability to recognize kids’ faces. It’s not some ability that just fades away with age.
It would be interesting to see if children are similarly better-able to recognize kids’ faces — and perhaps worse at recognizing adults!
Dana Kuefner, Viola Macchi Cassia, Marta Picozzi, Emanuela Bricolo (2008). Do all kids look alike? Evidence for an other-age effect in adults. Journal of Experimental Psychology: Human Perception and Performance, 34 (4), 811-817 DOI: 10.1037/0096-15220.127.116.111