The amygdala in your brain determines the distance you prefer for people standing near you. The ability to manipulate the brain to adjust this distance would have practical applications such as with manned space flight.
Pasadena, Calif.—In a finding that sheds new light on the neural mechanisms involved in social behavior, neuroscientists at the California Institute of Technology (Caltech) have pinpointed the brain structure responsible for our sense of personal space.
The discovery, described in the August 30 issue of the journal Nature Neuroscience, could offer insight into autism and other disorders where social distance is an issue.
The structure, the amygdala—a pair of almond-shaped regions located in the medial temporal lobes—was previously known to process strong negative emotions, such as anger and fear, and is considered the seat of emotion in the brain. However, it had never been linked rigorously to real-life human social interaction.
A woman with a damaged amygdala provides insight into its function.
The scientists, led by Ralph Adolphs, Bren Professor of Psychology and Neuroscience and professor of biology and postdoctoral scholar Daniel P. Kennedy, were able to make this link with the help of a unique patient, a 42-year-old woman known as SM, who has extensive damage to the amygdala on both sides of her brain.
"SM is unique, because she is one of only a handful of individuals in the world with such a clear bilateral lesion of the amygdala, which gives us an opportunity to study the role of the amygdala in humans," says Kennedy, the lead author of the new report.
This woman is less able to recognize fear in the faces of others and prefers to stand closer to people than they feel comfortable with.
SM has difficulty recognizing fear in the faces of others, and in judging the trustworthiness of someone, two consequences of amygdala lesions that Adolphs and colleagues published in prior studies.
During his years of studying her, Adolphs also noticed that the very outgoing SM is almost too friendly, to the point of "violating" what others might perceive as their own personal space. "She is extremely friendly, and she wants to approach people more than normal. It's something that immediately becomes apparent as you interact with her," says Kennedy.
SM is comfortable with standing nose-to-nose with another person.
The experiment used what is known as the stop-distance technique. Briefly, the subject (SM or one of 20 other volunteers, representing a cross-section of ages, ethnicities, educations, and genders) stands a predetermined distance from an experimenter, then walks toward the experimenter and stops at the point where they feel most comfortable. The chin-to-chin distance between the subject and the experimenter is determined with a digital laser measurer.
Among the 20 other subjects, the average preferred distance was .64 meters—roughly two feet. SM's preferred distance was just .34 meters, or about one foot. Unlike other subjects, who reported feelings of discomfort when the experimenter went closer than their preferred distance, there was no point at which SM became uncomfortable; even nose-to-nose, she was at ease. Furthermore, her preferred distance didn't change based on who the experimenter was and how well she knew them.
Think about the uses if one could suppress the feeling of discomfort in close quarters. Smaller personal space size would have obvious advantages for manned space flight. Going to take a many month trip to Mars? The ability to shrink personal space preferences would enable more relaxed feelings in smaller quarters.
Mines, submarines, even college dorms and subways put people very close to each other - uncomfortably close for many. Do you find yourself in situations where you'd like to be able to dial down your discomfort from being physically close to others?
By Randall Parker at 2009 August 30 09:42 PM Brain Innate
For pickpockets and pick-up artists, the search for an amygdala-zapper begins now.
This isn't especially decisive, as findings go. You've got *one* subject with (grantedly specific) brain damage. Jumping from that to grand conclusions about how personal space is perceived by everyone is kind of ambitious. It's still good work, it just needs a followup with PET scans or the like across a population of people before this kind of conclusive statement is justified...
Isn't this as much about the angle as the distance? The closer the other person is to a face-to-face dead on angle, the more space I need. I can sit side by side with somebody if we aren't looking at each other. My personal space bubble is a narrow, but long, oval
A sample size of 1 does not make for any credible or statistically sound conclusions. Good lessons learned from this situation could form the basis for continued future research for validation.
bye bye e-Harmony - helllloo no amygdala!
I still can't help but feel that cultural differences play by far the greatest role in this largely swamping out genetic factors. The Italians may feel far more comfortable standing closer to each other than say the English and yet I would be surprised if this difference was genetic.
It would be interesting to see if the Chinese people living in Shanghai or Hong Kong were more comfortable standing closer together than their rural genetic cousins. I suspect so.
There's a great Seinfield episodes about this phenonmenon. Jerry names them "close talkers".
This is from 'Mentalism and Mechanism: the Twin Modes of Human Cognition' by Christopher Badcock, an excellent article. Although it probably doesn't have any bearing on personal space, Dave's post reminded me of it.
Direction of gaze
From an evolutionary point of view, a plausible origin for theory of mind might be found in direction of gaze. Primates are typified by forward-rotated eyes, often to the extent that the visual axes of the eyes are practically parallel (as in the human case). The benefit of this is excellent stereoscopic vision, which would have served their ancestors well in the arboreal habitat in which primates almost certainly first evolved. However, the cost is a notable reduction in field of vision, particularly when compared with the almost panoramic view enjoyed by most mammals whose visual fields normally only overlap to a limited amount at the front, leaving only a small blind area behind the head. The result is that primates have become more social (and more vocal) so as to gain the advantage of many different pairs of eyes (Allman, 1999).
Primates have also compensated by becoming sensitive to the direction of gaze of others. This is particularly important because, not only can it tell you where the others in the group are looking, it can also give useful clues about what they are seeing, their state of mind, and intentions. (Indeed, an analogy now exists in military technology: radars function essential like eyes, and like them can be directed. Rules of engagement in some recent conflicts have allowed pilots to interpret a lock-on to their aircraft by an enemy radar as hostile, and to react immediately rather than wait for the missile-launch or gun-attack that might be expected to follow.)
In other words, not only may direction of gaze have an important social dimension in primates like human beings, it also may have evolved as a critical and fundamental factor in primate sociality from the beginning. What might at first have seemed an after-effect of social behaviour, or a trivial detail in it, now begins to take on the appearance of a central, strategic social adaptation.
There is now good evidence that autistics are notably lacking in awareness of direction of gaze, and are poor at interpreting its psychological significance. If there is indeed a mental module specialized for gaze-monitoring as some have speculated, it appears to be defective in their case. However, there are also reasons for thinking that it could be over-active, or at least that some people may over-interpret its output. Here the best example is the delusion of being watched or spied-on that is so typical of paranoia.
The most famous paranoiac in the psychiatric literature was Daniel Paul Schreber (1842-1911), a German high-court judge who published an autobiographical account of his illness that was later the subject of a paper by Sigmund Freud (Freud, 1911; Schreber, 1903). Schreber included in it a section entitled 'Direction of Gaze' long before the subject had been introduced into discussions of theory of mind (chapter XVIII). According to Schreber the sun was a living being who spoke to him in human language, or was the organ of a higher being lying behind it (Schreber, 1903:47). Although impossible before his illness, in the course of it Schreber believed he could look at the sun without blinking - indeed, the sun's rays visibly paled before him when he did so (quoted by Freud, 1911: 53-4).
Schreber also often railed at the sun, which at times he saw as God's eye, and paranoiacs are often morbidly sensitive to other people's direction of gaze to the extent of interpreting it as hostile and/or intrusive. Indeed, they sometimes feel that they are being watched even when no one is there. Nowadays they often extend this naturally-evolved sensitivity about direction of gaze to modern technological surrogates for it, and become similarly pathologically pre-occupied with cameras, closed-circuit TV and ray- or radiation-producing mechanisms of many different kinds. Such delusions might fit nicely under another of Schreber's headings: 'Egocentricity of the rays regarding my person' (Schreber, 1903, chapter XX). Indeed, Harry Stack Sullivan (1892-1949), a psychiatrist famed for treating schizophrenics, advised his colleagues to sit at the side of such a patient rather than facing them, never to look them in the eyes (which he found created suspicion), and to address them in the third person (personal communication from Dr Andy Thompson, quoted with thanks by kind permission).