Great Discoveries in Psychology: Mirror Neurons

It is hard to imagine a better job than being a college professor, except maybe being a tenured professor at a university that encourages interdisciplinary fusion. This semester, I am teaching a new course called “The Discovery of Human Nature.” I started out as a biology major, considered switching to anthropology, and although I ended up with an official label of a social psychologist, I have dabbled in clinical psychology, personality psychology, developmental psychology, cognitive psychology, and behavioral economics along the way.

Perhaps all that dabbling stems from a proclivity toward attention deficit disorder or a defective personality trait that inclines one to be a hopeless dilettante. But the upside of the problem is an appreciation for big broad perspectives that can tie together all the disparate factoids I’ve encountered along my meandering intellectual journey.

The joys of integrative science

Arizona State University turns out to be one of the best places on the planet to think about behavior in terms of broad integrative theory. Our faculty includes some of the world’s most prominent evolutionary biologists, including John Alcock, Bert Holldoebler, and Randy Nesse. And over in anthropology, there is a similarly distinguished cast of evolutionary thinkers who have explored human nature across human groups and even different species. These include Kim Hill, Rob Boyd, and Joan Silk (along with Randy Nesse, they were all founding members of the Human Behavior and Evolution Society). And in my own department, we have a great cast of psychologists who have studied human behavior through the lenses of evolution, culture, and cognitive science.

The students in my new course have not only enjoyed guest lectures by all those brilliant biologists and anthropologists I just named, but they’re also heard inspirational lectures from and had conversations with several world-class cognitive psychologists and neuroscientists (Jay Braun, Art Glenberg, Greg Stone, Clive Wynne, Vaughn Becker, and Sam McClure), and social psychologists who’ve viewed various aspects of human behavior in terms of evolution and culture (Steve Neuberg, Robert Cialdini, Lani Shiota, Michael Varnum, and Athena Aktipis). Besides all that, we began the semester with a visiting lecture from Bill von Hippel of the University of Queensland, who talked about his new book The Social Leap, in which he argued that human psychology evolved out of the need to band together to defend ourselves against predators on the East African Savannah, after geological events caused our ancestral jungles to disappear, stranding us out in the open as potential meals for lions and tigers.

One great discovery: Mirror Neurons and Embodied Cognition

Part of what makes my job so great is that I am always learning new things, and every one of the guest lecturers in my course has taught me something. Just yesterday, for example, students heard Art Glenberg, who is a prominent researcher in the area of “embodied cognition.” When I asked Art to nominate a finding that has changed our view of human nature, he pointed to the discovery of mirror neurons by Giacomo Rizzolatti and his colleagues at the University of Parma. Glenberg had in fact actually nominated Rizzolatti’s discovery for a prestigious Grawemeyer Award, and Art also hinted that Rizzolatti’s discovery might someday win a Nobel Prize (Daniel Kahneman and Amos Tversky’s work won both a Grawemeyer and a Nobel Prize, for instance).

Giacomo Rizzolatti, Univ. of Parma

Source: original composition by blog author Douglas Kenrick, based on photo from Art Glenberg, used with permission

What’s so cool about mirror neurons? Glenberg explained how the discovery of mirror neurons was completely serendipitous, and also why it was so awe-inspiring. Rizzolatti and his colleagues were trying to map the motor cortex of macaque monkeys, and they had discovered one set of neurons that only fired when the monkey made a particular movement (reached out to pick up a raisin, for example). That set of neurons did not fire when the monkey made other movements, so it seemed to have a very narrow function. But then something strange happened: When one of the experimenters reached out to grab the raisin, the monkey’s neuron started firing. The neuron did not fire when the experimenter made other movements, only when it reached for the raisin. It seemed as if watching a particular action led the monkey’s brain to respond as if the monkey himself was performing the movement.

Later research suggested that mirror neurons respond not so much the physical movement itself, but the intention. When the monkey watched a person make a grasping movement but there was nothing to pick up, his brain did not fire. And most interestingly, when the experimenters put up an obstacle to block the monkey’s view of the grasping movement but allowed the monkey to see the hand moving in that direction, the monkey’s brain cells fired at the exact moment that the hand would have been grasping the object. Most amazingly, if the experimenter lifted the barrier and removed the object, so the monkey knew there was nothing to pick up, then replaced the barrier and let the monkey watch the hand move behind the barrier, there was no firing. The monkey was aware that there was nothing to pick up, so there was no activity in the mirror neuron.

Why is the discovery of mirror neurons so important to our understanding of human nature? According to Glenberg, mirror neurons shine a light on how it is that human beings can understand one another’s humanity, suggesting that when we watch another person behave, our own nervous systems simulate or resonate with another person’s behavior. As he notes: “ the people in Parma like to say it’s an understanding from the inside.” In a sense, when I watch you behave, my brain becomes you.

Glenberg also talked about how the research on mirror neurons connects with his own fascinating research on “embodied cognition,” and on how these findings challenge the traditional models of how the mind works. If you’re interested, you can watch our conversation by clicking the link below.

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