Study finds that the same face may look male or female depending on where it appears in person's field of view

November 24, 2010 by Anne Trafton
Subjects in the study were shown computer-generated faces, created with FaceGen software, that ranged along a spectrum from very male to very female. Image: Arash Afraz

(PhysOrg.com) -- Neuroscientists at MIT and Harvard have made the surprising discovery that the brain sees some faces as male when they appear in one area of a person's field of view, but female when they appear in a different location.

The findings challenge a longstanding tenet of neuroscience — that how the sees an object should not depend on where the object is located relative to the observer, says Arash Afraz, a postdoctoral associate at MIT's McGovern Institute for Brain Research and lead author of a new paper on the work.

"It's the kind of thing you would not predict — that you would look at two identical faces and think they look different," says Afraz. He and two colleagues from Harvard, Patrick Cavanagh and Maryam Vaziri Pashkam, described their findings in the Nov. 24 online edition of the journal .

In the real world, the brain's inconsistency in assigning gender to faces isn't noticeable, because there are so many other clues: hair and clothing, for example. But when people view computer-generated faces, stripped of all other gender-identifying features, a pattern of biases, based on location of the face, emerges.

The researchers showed subjects a random series of faces, ranging along a spectrum of very male to very female, and asked them to classify the faces by gender. For the more androgynous faces, subjects rated the same faces as male or female, depending on where they appeared.

Study participants were told to fix their gaze at the center of the screen, as faces were flashed elsewhere on the screen for 50 milliseconds each. Assuming that the subjects sat about 22 inches from the monitor, the faces appeared to be about three-quarters of an inch tall.

The patterns of male and female biases were different for different people. That is, some people judged androgynous faces as female every time they appeared in the upper right corner, while others judged faces in that same location as male. Subjects also showed biases when judging the age of faces, but the pattern for age bias was independent from the pattern for gender bias in each individual.

Afraz believes this inconsistency in identifying genders is due to a sampling bias, which can also be seen in statistical tools such as polls. For example, if you surveyed 1,000 Bostonians, asking if they were Democrats or Republicans, you would probably get a fairly accurate representation of these percentages in the city as a whole, because the sample size is so large. However, if you took a much smaller sample, perhaps five people who live across the street from you, you might get 100 percent Democrats, or 100 percent Republicans. "You wouldn't have any consistency, because your sample is too small," says Afraz.

He believes the same thing happens in the brain. In the visual cortex, where images are processed, cells are grouped by which part of the visual scene they analyze. Within each of those groups, there is probably a relatively small number of neurons devoted to interpreting gender of faces. The smaller the image, the fewer cells are activated, so cells that respond to female faces may dominate. In a different part of the visual cortex, cells that respond to male may dominate.

More information: "Spatial Heterogeneity in the Perception of Face and Form Attributes" by Arash Afraz, Maryam Vaziri Pashkam, and Patrick Cavanagh. Current Biology, 24 November, 2010

Related Stories

Recommended for you

Researchers find monkey brain structure that decides if viewed objects are new or unidentified

August 18, 2017
A team of researchers working at the University of Tokyo School of Medicine has found what they believe is the part of the monkey brain that decides if something that is being viewed is recognizable. In their paper published ...

Artificial neural networks decode brain activity during performed and imagined movements

August 18, 2017
Artificial intelligence has far outpaced human intelligence in certain tasks. Several groups from the Freiburg excellence cluster BrainLinks-BrainTools led by neuroscientist private lecturer Dr. Tonio Ball are showing how ...

Study of nervous system cells can help to understand degenerative diseases

August 18, 2017
The results of a new study show that many of the genes expressed by microglia differ between humans and mice, which are frequently used as animal models in research on Alzheimer's disease and other neurodegenerative disorders.

How whip-like cell appendages promote bodily fluid flow

August 18, 2017
Researchers at Nagoya University have identified a molecule that enables cell appendages called cilia to beat in a coordinated way to drive the flow of fluid around the brain; this prevents the accumulation of this fluid, ...

Researchers make surprising discovery about how neurons talk to each other

August 17, 2017
Researchers at the University of Pittsburgh have uncovered the mechanism by which neurons keep up with the demands of repeatedly sending signals to other neurons. The new findings, made in fruit flies and mice, challenge ...

Neurons involved in learning, memory preservation less stable, more flexible than once thought

August 17, 2017
The human brain has a region of cells responsible for linking sensory cues to actions and behaviors and cataloging the link as a memory. Cells that form these links have been deemed highly stable and fixed.

1 comment

Adjust slider to filter visible comments by rank

Display comments: newest first

gwrede
3 / 5 (2) Nov 25, 2010
Seeing a face, the gender of which you don't already know, at the periphery of your visual field, implies this person appeared unexpectedly, and you don't know who it is.

This all means the person could be male or female, friend of foe. Now, females almost never require split-second action, whereas a male might very well require it. He could be from the other tribe, out to get you.

One would expect an advantage in erring on the side of male and foe, until you have time to recognize the person, or their intentions. That split-second may have been the difference of life and death, millions of times in history.

Please sign in to add a comment. Registration is free, and takes less than a minute. Read more

Click here to reset your password.
Sign in to get notified via email when new comments are made.