Standing at the airport waiting for a friend or relative to
emerge from a flight can be a frustrating experience. People come pouring out of the exit, and you
are searching for one person in particular.
On a crowded day, you might not even be able to get that close to the
exit, and so it can be hard to see the person you are looking for. Yet, most of the time, you manage to find the
person you seek.
Part of what helps you to identify friends and relatives is
information about their body. You
recognize their height, body shape, and even their manner of walking. In fact, all of that may help you to know who
you are looking at before the person is close enough to really see his or her
face.
An interesting paper in the November, 2013 issue of Psychological Science by Allyson Rice,
Jonathon Phillips, Vaidehi Natu, Xiaobo An, and Alice O’Toole demonstrates that
people use information about the body to identify people, but they are not
aware that they are doing so.
In these studies, participants saw pairs of pictures drawn
from a large database. Participants had
to identify whether the pair of pictures showed the same person or different
people. The pictures used in the study
were carefully selected so that this task was quite difficult. Many of the pictures of the same person were
rather dissimilar, while many of the pictures of different people were similar
to each other. As a result, face
information alone was not helpful in determining whether the people in each
pair were similar.
When participants were given the full pictures, they were
reasonably accurate in making the judgments of which pictures were the same or
different. Some participants were shown
only the faces from the pictures. This
group was not good at all at distinguishing the same and different pairs. A third group saw only the bodies with the
faces covered by an oval. This group was
about as accurate at identifying the pictures as the group who saw the full
pictures.
So far, this probably doesn’t seem so surprising.
In another study, participants were given the full pictures
to judge. Afterward, they were asked
about a variety of facial and bodily features, and were asked how much they
used this information to make the judgments.
Participants performed well in this study, suggesting that they had to
be using information about the body, but their ratings suggested they believed
that they were focused on the nose, face shape, ears, mouth, eye shape and eyebrows,
but not on properties like the hair length, height, shoulders, and neck.
These ratings suggest that people are mistaken. That is, when people see just the face
information, they are not able to distinguish between the pictures of the same
people and pictures of different people.
The body shape information is important, yet people do not report using
it.
A final study demonstrated that people really were reporting
the information they used to make judgments incorrectly. In this study, participants saw full
pictures. They viewed the picture pairs while their eyes were being tracked. Eye tracking enables researchers to monitor
what people are looking at on a moment-by-moment basis. The technique is effective, because you clear
vision for only a small area (about the size of your thumbnail at arm’s
length). So, your eyes are constantly in
motion to create a clear image of what you are seeing.
In this eye tracking study, some of the pairs of pictures
were ones in which face information could be used to make reasonably accurate
judgments. Other pairs required body
information to be used. When the face
information was helpful for making judgments, people looked at it quite a
bit. When the face information was not
helpful for making judgments, then people focused more on areas of the body
that would help them to determine whether the two people were the same.
What does this mean?
First of all, your visual system is smart. It does a good job of figuring out the
information you need to make judgments.
Second, you do not have complete access to all of what your
visual system is doing. Even though you shift your attention from the face to
the body when body information will help you to recognize a person, you still
think that you are focused on the person’s face. This is another great example of how your
conscious experience of what you are doing is not an accurate portrayal of what
you are actually doing.