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Take a look at this animation. One face will flash; then it will be followed by another face. Are the two faces the same or different? The change between faces could be a small one.
Did you notice a change? (You can repeat the movie once if you're not sure.) Let's make this one a poll:
Now try another animation:
Again, were the faces the same or different?
Most people are much better at identifying different human faces than identifying animal faces, which makes sense, since most people have more experience with other people than with animals.
Most adults are also better at distinguishing between human faces than kids are. But why is this the case? It might be because adults have more experience with faces, but it might be because of adults' generally better cognitive performance. A team led by Catherine Mondloch devised a study which attempts to resolve this question.
Mondloch's team showed adults and children faces like the ones shown above. Half the faces were human, and half were monkey faces. Half the time the faces were the same, and half the time faces were slightly different -- the eyes or mouths were moved just a few millimeters from their original location using computer software.
How did adults and children compare? Here's a graph of accuracy in judging whether the faces were the same or different:
As expected, both adults and children were better with human faces compared to animal faces. But adults were better than kids in both categories. This experiment establishes the validity of this test, but it still doesn't answer the more basic question of why adults are better. To address this question, a new test was devised, where the faces of 8-year-old children were substituted for the monkey faces. Here are those results:
You might expect that 8-year-olds, who spend each day in class with dozens of kids their same age, might be better at distinguishing between 8-year-old faces than adults. But in fact there was no significant difference in accuracy for comparing 8-year-old faces versus adult faces, for either adults or kids. Adults were still significantly more accurate than kids, both for adult faces and 8-year-old faces.
The researchers say this demonstrates that adults aren't better at face recognition because of experience: arguably kids have more experience with the faces of kids their own age. This must mean that adults' superior ability to recognize faces is due to their greater general cognitive ability. This would also explain why adults are better at recognizing monkey faces.
So which faces were different in our demonstration above? Both the human and monkey faces! If you're like me (and most other people), the monkey face test was significantly more difficult for you!
Mondloch, C.J., Maurer, D., & Ahola, S. (2006). Becoming a face expert. Psychological Science, 17(11), 930-934.
Comments
I should add that human and monkey faces are different by the exact same amount. Our results, so far, are even more dramatic than the researchers'! Though I imagine, after even just a few repeated trials, humans might become better at recognizing monkey face differences.
Posted by: Dave Munger | February 13, 2007 4:45 PM
I have a doubt: Adults have experience of 8 year old faces throughout their entire life--but 8 year olds have only had 8 years of exposure to 8 year old faces, and only a year or so of concentrated exposure because of school. I'm not sure that that concentrated exposure is enough to overcome the lifetime of experience that adults have had--including a year of concentrated exposure themselves, way back when they were eight. How about distinguishing between, say, Pokemon faces?
Posted by: Rob Rushing | February 13, 2007 5:20 PM
"I have a doubt: Adults have experience of 8 year old faces throughout their entire life"
Also: adults' experience with adult faces is probably useful when it comes to recognizing children's faces.
Posted by: brtkrbzhnv | February 13, 2007 6:06 PM
I have the same doubt. I think adults have better (quantity) experience with 8yo faces, but it's less accessed by memory, so it's weaker (quality). But the 2 things (plus better general face recognition and cognitive performance) balanced give better accurary for adults yet.
Perhaps the answer is "both" (experience with faces and better cognitive performance, since the test doesn't proves the contrary).
Posted by: Rafael C.P. | February 14, 2007 7:24 AM
I have the same doubt. I think adults have better (quantity) experience with 8yo faces, but it's less accessed by memory, so it's weaker (quality). But the 2 things (plus better general face recognition and cognitive performance) balanced give better accuracy for adults yet.
Perhaps the answer is "both" (experience with faces and better cognitive performance, since the test doesn't proves the contrary).
Posted by: Rafael C.P. | February 14, 2007 7:25 AM
The distorted human face looked a little photoshopped, which is why I think I chose that they looked different. I wonder how much that would have an effect on adult/child responses?
Posted by: Eve | March 1, 2007 11:04 AM
"The researchers say this demonstrates that adults aren't better at face recognition because of experience: arguably kids have more experience with the faces of kids their own age."
Um, hm, this fails the common sense test.
The child has experience of 8-year old faces.
The adult has that *same* experience (after all, every adult was once eight years old) *plus* a whole bunch of other experiences (including additional experiences of eight-year olds).
If experience is cumulative (at least in part, surely a defensible proposition) then the 'researchers' are wrong.
Posted by: Stephen Downes | March 3, 2007 9:46 AM