Cognitive Daily

Face recognition is a task which humans do with little effort, even though in fact it’s a tremendously difficult problem. To recognize a face, we need to be able to ignore traits that change over time, while focusing in on details that remain constant. A simple computer program, for example, would have difficulty recognizing that Jim frowning (before his fries arrive) is the same person as Jim smiling (after his fries arrive).

The fact that we have little difficulty recognizing our friends and family regardless of their facial expressions has led researchers to speculate that recognizing faces is accomplished by an entirely different system from recognizing facial expressions.

But in 1998, S. R. Schweinberger and G. R. Soukup found that we take longer to recognize emotions in different individuals than in the same person. Yet we recognize the individuals at the same speed, regardless of facial expression. They argued that recognizing emotions must not be entirely separate from recognizing individuals. However, an alternate explanation is possible: perhaps faster tasks can interfere with slower tasks, but the reverse does not occur. Since classifying identity takes less time than recognizing emotion, then this may be the root of the difference.

A team led by Anthony Atkinson has developed a set of experiments to test whether the interaction between identity processing and emotion processing is related to processing speed. They asked 32 college students to look at a series of photos of faces and identify either their emotion (fearful or happy) or gender. For the emotion group, half the time the gender of the faces remained the same, and half the time the gender changed from photo to photo. The same procedure was reversed for the gender group. Here are the results:

The results matched those of Schweinberger and Soukup: When classifying emotions, then reaction is slower when the gender of the face in the photos changes, but changes in facial expression don’t slow gender classification. Again, this could be explained by the fact that gender classification is faster than emotional classification.

To address this discrepancy, Atkinson’s team developed a second experiment where the difficulty of the gender and emotion tasks was systematically varied. Faces from each extreme of sex or emotion were blended together at different levels. For example, in one condition, viewers saw faces that were 75 percent male and 25 percent female and vice versa. The reaction times for this condition turned out to be the same as when emotions were displayed at the 75-25 level. Here are the results for this group:

Now, as before, the reaction time was slower during emotion classification when the gender of the faces changed. Reaction time actually decreased during gender classification when the emotion changed. Atkinson et al thus offer convincing evidence that face recognition and emotion recognition must be relying on at least some of the same mental processes.

The implication, of course, is that face and emotion recognition are extremely complex processes — and indeed that the two processes are to some extent intertwined. While it’s not true that Jim is literally a different person before he gets his French fries, there’s no doubt that he sometimes appears that way to others!

Atkinson, A.P., Tipples, J., Burt, D.M., & Young, A.W. (2005). Asymmetric interference between sex and emotion in face perception. Perception and Psychophysics, 67(7), 1199-1213.

Comments

#1 Jim
October 30, 2006

By the way, that’s an old picture of me. As in, really really old. Really, it’s old.
#2 Scott
October 30, 2006

Did you ever have the experience of looking at someone you’ve known for a while, and all of a sudden something in your perception shifts, and the person now looks “different” somehow? If you’re quick, you can shift back and forth from the “old” perception to the new, but very quickly the “new” perception “sticks”, and you can’t go back. It’s kind of like those clever line drawings that can look like two images, for example, the one that looks like the face of an old woman and (at almost the same time) a left-rear-quarter view of a young woman. Yet, this happens with a real person. I’ve had it happen to me many times over the years.
#3 Luis
October 30, 2006

I am in a Neuroscience class and face recognition is pretty interesting. Some people who have had certain brain damage can still recognize faces but cannot remember who they are recognizing.
#4 Michael
October 30, 2006

Have you ever been in the same room as, or engaged in conversation with, someone from your past but you simply did not recognise them? I have had this happen on 2 occasions. I met this dude a few years ago and we became friends. We later realised we used to be friends when we were kids (about 20 years earlier) yet neither of us made the immediate recognition.

And another time, I had e meeting with a client who later it turned out was a guy I went to high school with and we shared the same classes.

The funny thing is in my minf I still had clear memories of these 2 people from th epast – my mind simply didn’t allow for the time that had lapsed.
#5 Carol
October 31, 2006

And some of us don’t recognize faces at all. I go with body and hair color/shape and context clues. Are you sitting behind the desk in Mary’s office? You must be Mary. Are you in my bed snoring? You must be my husband. Are you surly and do you regularly break my buttons? You must be my dry cleaner. Yeah, I know. I need to get a new dry cleaner.

My favorite cover technique if my regular stuff doesn’t tell me who you are is to cut you off at the pass so I don’t have to greet you as if I know you. You walk up to me in the hallway and say “Hi Carol!” I compliment you (sincerely) on the color of your blouse, on your nail polish, on your broad, incredibly sexy shoulders (OK that one I do only in my head). By the time you’ve told me you bought that blouse at 50% off, I’ve recognized your voice or we’ve at least passed the greeting stage so you will talk about other stuff that helps me figure out who you are.
#6 Lynn
November 1, 2006

When I think about it, I recognize that the boy in the left photo is the same boy in the right photo because:

1. He is wearing the same clothing and seems to be the same size.

2. He is sitting in the same seat with the same things in the foreground and backgound.

3. The body looks the same.

4. Finally, I look at the hair and then the face.

5. Then I notice the McDonalds food and wonder about the sequence of events that led to the photos.

In any case, my brain went through a bunch of very quick comparisions and deductions to conclude that the boy on the left was also the boy on the right, but in a different position and at a slightly different time.

Which goes to show, Jim, that neither you nor I are one fry short of a happy meal.

Sorry, I couldn’t resist the pun.
#7 Richard
November 3, 2006

disclaimer: I know nothing.

Regarding the last experience, what comes to mind is this:
Having just seen the facial expression in one or a few of a gender, I might use that as a cue or a prototype to suggest what the current gender should be, and this would mislead me. Getting a different facial expression would require a fresher determination unhindered by a facial expression’s recent familiarity.
#8 Organic Chemistry
March 15, 2007

disclaimer: I also know nothing.

Different muscles are involved when one is frowning vs. smiling. Could a program not be created to see when those muscles are being contracted and then determine whether is a smile or frown???