August 2, 2010

Theory of mind

Posted in Language and Myth tagged , , at 2:26 pm by Jeremy

Here’s the third section of the Chapter 2 draft of my book, Finding the Li: Towards a Democracy of Consciousness. This section discusses theory of mind as a crucial part of what makes us human.  It quotes Michael Tomasello on the cognitive differences between humans and chimpanzees, contrasts theory of mind with empathy, and locates it in the medial prefrontal cortex.  All constructive comments from readers of my blog are greatly appreciated.


Theory of mind.

In 1978, primate researchers Premack and Woodruff published what was to become a seminal paper entitled “Does the chimpanzee have a theory of mind?”.[1] This was the first time that the phrase “theory of mind” had been used in the scientific literature, which they described as an ability to represent and infer the mental states of others.  It “may properly be viewed as a theory,” they stated, “because such states are not directly observable, and the system can be used to make predictions about the behaviors of others.”[2]

More recently, Tomasello has conducted extensive research into how theory of mind differentiates us from other primates.  He gives a list of social actions that we take for granted but which nonhuman primates simply don’t do:

In their natural habitats, nonhuman primates:

  • Do not point or gesture to outside objects for others;
  • Do not hold objects up to show them to others;
  • Do not try to bring others to locations so that they can observe things there;
  • Do not actively offer objects to other individuals by holding them out;
  • Do not intentionally teach other individuals new behaviors.[3]

Chimpanzees gesture a lot but they don't point to objects

He believes that they don’t do these things because they “do not understand others as intentional agents in the process of pursuing goals or mental agents in the process of thinking about the world.”  In his view, the biological makeup of chimpanzees’ and humans’ brains would be very similar except for the one major difference that we humans “identify” with others of our species “more deeply than do other primates.”  It’s from this “one uniquely human, biologically inherited, cognitive capacity,” he believes, that all the other uniquely human traits emerged.[4]

It’s important to understand that, although they’re similar, theory of mind is not the same thing as empathy.  As neuroscientist Tania Singer points out, empathy is all about sharing the feelings and emotions of another person.  Imagine you’re a volunteer helping out in a foreign country that’s just suffered a natural disaster.  You might be sitting with a woman who’s just lost her children, putting your arm around her while she’s sobbing in grief.  Perhaps she speaks no English, and you know nothing about her life other than her grief.  You would probably feel intense empathy for her, even if you had no idea what thoughts, intentions or beliefs are going through her mind.  On the other hand, you can apply your theory of mind on people for whom you have no empathic feelings whatsoever, such as a rival you’re competing against in your profession.

Theory of mind is different from empathy

One reason this distinction is important is that empathy and theory of mind are believed to arise from different neural pathways in the brain.  Singer, who has reviewed multiple brain imaging studies on the subject, explains that empathy activates the same emotional circuits in our brains and bodies that come alive when we have our own feelings.[5] Here, we can see how those mirror neurons are most likely springing into gear, mirroring not just the actions but the feelings of those we care about.  On the other hand, theory of mind activates a different set of brain areas, most notably the pfc.

In fact, it’s a specific area within the pfc called the medial prefrontal cortex that gets activated when we exercise our theory of mind.  This is especially interesting because it’s exactly the same part of the pfc that gets activated when we exercise our self-awareness and think about ourselves.  In the words of one study, “data indicate that the ability to reflect on one’s own mental states, as well as those of others, might be the result of evolutionary changes in the prefrontal cortex.”[6] In another study, subjects were asked to think about themselves in a wide variety of different states, including pain, tickling, actions and looking at pictures.  In all this variety, the one part of the brain that was consistently activated whenever the subjects were thinking about themselves was the medial prefrontal cortex.[7]

The fact that the medial prefrontal cortex is activated when thinking both about yourself and others suggests a fundamental linkage between the evolution of theory of mind and that other uniquely human trait, self-awareness.  This linkage can be seen, not just in the actions of our pfc, but also in the developing mind of an infant.  A child doesn’t develop a fully fledged theory of mind until she’s reached around 3-5 years of age.  But even in the first few months of an infant’s life, Tomasello describes how, in their attempts to understand other people around them, infants “apply what they already experience of themselves,” making the judgment that “others are ‘like me’ and so they should work like me as well.”  Tomasello then traces what he calls a “social-cognitive revolution” that occurs in infants at around nine months.  Around that age, an infant begins to follow someone else’s gaze and direct other people’s attention to something she cares about.  At some point, the infant realizes that the other person’s attention is directed at her!  “She now knows she is interacting with an intentional agent who perceives her and intends things toward her.”  Before too long, the infant realizes that her actions affect other people’s emotional states.  “This new understanding of how others feel about me opens up the possibility for the development of shyness, self-consciousness, and a sense of self-esteem.”  The infant has begun to participate in the social universe.  Tomasello notes as evidence of this that, around the first birthday, an infant begins to show the “first signs of shyness and coyness in front of other persons and mirrors.”[8]

The key point in this infant’s drama is that it takes an understanding of other people as intentional agents to begin to arrive at an awareness of yourself.  And it takes both of these steps together to develop a sense of yourself as a social agent, someone interacting in society.  It’s when the hominid brain began to use its theory of mind and self-awareness for social purposes that the evolution towards modern homo sapiens really got going.  In fact, over the past thirty years, a powerful theory called the Social Brain Hypothesis has gained increasing acceptance as an explanation for the full development of our unique human cognition.


[1] Premack, D., & Woodruff, G. (1978). “Does the chimpanzee have a theory of mind?” Behavioral and Brain Sciences, 4, 515–526.

[2] Cited in Povinelli, D. J., and Preuss, T. M. (1995). “Theory of mind: evolutionary history of a cognitive specialization.” Trends in Neurosciences, 18(9:November 9, 1995), 418-424.

[3] Tomasello, M. (2000). The Cultural Origins of Human Cognition, Cambridge, Mass.: Harvard University Press, 21.

[4] Ibid.

[5] Singer, T. (2006). “The neuronal basis and ontogeny of empathy and mind reading: Review of literature and implications for future research.” Neuroscience and Biobehavioral Reviews(30 (2006)), 855-863.

[6] Povinelli and Preuss, op. cit.

[7] Frith, C. D., and Frith, U. (1999). “Interacting Minds – A Biological Basis.” Science, 286, 1692-1695.

[8] Tomasello, op. cit., 89-90.

April 22, 2010

Even bugs have values! – The biological foundation of human ethics.

Posted in Values and the pfc tagged , , , at 3:44 pm by Jeremy

Oh God said to Abraham, “Kill me a son”
Abe says, “Man, you must be puttin’ me on”

Bob Dylan stated it clearer than most: the irresolvable conflicts that can arise when different value systems clash.  In one of the most memorable scenes of the Old Testament, God wants to test Abraham’s faith, so he tells him to sacrifice his son, Isaac.  Abraham is faced with a clash of values: his paternal bond to the son he loves versus his commitment to an invisible, all-powerful authority.  And even to this day, that conflict resounds.  As Nobel laureate Steven Weinberg notes in a 2008 article in the New York Review of Books, “even someone who believes in God can feel that Abraham in the Old Testament was wrong to obey God in agreeing to sacrifice Isaac.”[1]

Abraham sacrificing Isaac: a fundamental clash of values.

Where do these different values systems come from?  Why do they conflict with each other?  And how do they affect the way we live our lives every day?  In a series of blog posts, I’m going to explore these questions.  We’ll see the crucial role that the prefrontal cortex (pfc) plays in constructing our values.  And if you follow me to the end, perhaps we can arrive together at some ideas about how we might evolve our value system to respond to major 21st century issues such as our ever-accelerating effects on the global environment.

Oftentimes, when people talk about values, they begin with some great externality such as God.  Alternatively, more recently, many evolutionary psychologists note the fact that homo sapiens has spent 99% of its career in bands of hunter-gatherers, and focus accordingly on the core values that evolved in that environment.  I agree in general with the approach of the evolutionary psychologists, but I think if you really want to understand values, you have to go back even further.  Values begin in the body.  Values were embodied before we evolved the capacity to talk about them.  And, in fact, I’d go back even further than that.  Back to the very earliest, primeval times on the earth.  Back to the days, over a billion years ago, when the only living things around were single-celled organisms.

What, you might ask, does a bacterium wallowing around in a primordial ooze have to do with values?  Stuart Kauffman explains it well:

Consider then a bacterium swimming up the glucose gradient.  The biological function that is being fulfilled is obtaining food… Here, the bacterium detects a local glucose gradient, which is a sign of more glucose in some direction.  By altering its behavior and swimming up the gradient, the bacterium is interpreting the sign… Thus meaning has entered the universe: the local glucose gradient is a sign that means glucose is – probably – nearby.  Because natural selection has assembled the propagating organization of structures and processes that lead to swimming up the glucose gradient for good selective reasons, glucose has value to the bacterium.[2]

A pseudomonas bacterium: even it has values.

OK, I hear you say, but that’s cheating.  Maybe the glucose has value to the bacterium, but that’s not the same as our values… we’ve advanced well beyond that.  Yes, we certainly have.  For one thing, we have brains with complex neurological structures that no bacterium can ever imagine.  But our brains evolved in order to help the other parts of our body do their jobs more efficiently.  Our bodies are, after all, composed of about ten trillion cells, and each of these cells, just like that bacterium, needs nutrition in order to live its life to the full and keep us healthy.  So it’s not surprising that neuroscientist Antonio Damasio, one of today’s leading theoreticians on human consciousness, sees an inextricable link between amoebas and us:

A simple organism made up of one single cell, say, an amoeba, is not just alive but bent on staying alive.  Being a brainless and mindless creature, an amoeba does not know of its own organism’s intention in the sense that we know of our equivalent intentions.  But the form of an intention is there, nonetheless, expressed by the manner in which the little creature manages to keep the chemical profile of its internal milieu in balance while around it, in the environment external to it, all hell may be breaking loose…

What I am driving at is that the urge to stay alive is not a modern development.  It is not a property of humans alone.  In some fashion or other, from simple to complex, most living organisms exhibit it.  What does vary is the degree to which organisms know about that urge.  Few do.  But the urge is still there whether organisms know of it or not.  Thanks to consciousness, humans are keenly aware of it…[3]

Between the two extremes of self-aware humans and amoebas lie the millions of species of multi-celled organisms that inhabit our world.  For many of these species – the animals – a nervous system evolved to create a bi-directional feedback system connecting the brain with the other billions of cells that make up the animal’s body. In a 2009 paper, physiologist Michel Cabanac traces the evolution of the nervous system from an elemental reflex-oriented mechanism to a more sophisticated one where a basic form of consciousness appears.[4] Cabanac sees a major transition occurring between the class of animals that nowadays includes amphibians such as frogs and toads and the class that led to other animals such as birds, turtles, snakes and mammals.  For amphibians, a basic feeling will elicit a hard-wired, instinctual response.  A frog feels hunger and sees a rapid movement in front – its tongue shoots out to catch a fly.   But for more evolutionarily sophisticated animals, responses go beyond these basic steps.  A far more complex series of primary emotions, such as anger or fear, can drive the animal’s response.

A frog: Cabanac contrasts its hard-wired instinct to creatures with basic emotions.

With the evolution of humans, something unique happens to those primary emotions.  The symbolizing power of the human prefrontal cortex enables us to experience a range of emotions that go way beyond simple things such as anger or fear.  Our complex social awareness leads us into areas such as pride, shame, and all kinds of intangible emotions far too nuanced to even have a name attached to them.[5] And finally, we humans have awareness of these emotions.  So, whereas another animal can feel anger, only a human has the ability to look at herself and say “I feel angry.”  See the diagram below for a visualization of these differences (click on it for a bigger version).

Now, we’re getting close to the point where we can begin to understand how our values arise out of those embodied emotions that evolved over hundreds of millions of years.  In an interesting 2007 paper, psychologist Darcia Narvaez has traced what she calls the “neurobiological roots of our multiple moralities.”[6] She takes as her evolutionary framework the model devised by renowned neuroscientist P.D. Maclean called the “triune brain theory,” which views the human brain as comprising three layers: an evolutionarily ancient “reptilian” brain enveloped by an “early mammal” brain, which is in turn overlaid by the more recent neocortex (which incorporates the pfc.)

In Narvaez’s view, each of these three layers drives different sets of ethical values, leading to our current human condition where “three distinctive moral systems, rooted in the basic emotional systems, propel human moral action on an individual and group level.”  In summary, here’s the gist of her three systems:

  • The “Reptilian brain” produces a Security Ethic incorporating physical survival, fear, anger, basic sexuality.
  • The “Early Mammalian brain” produces an Engagement Ethic incorporating feelings of intimacy, care-giving, loneliness and sorrow.
  • The Neocortex produces an Ethic of Imagination incorporating logic, reason, consideration of alternative actions and “perspective taking.”

So now we’ve reached the starting point.  We don’t necessarily have to accept the exact categorizations that Narvaez offers, but the general framework is what’s most important.  We can now begin to see how God telling Abraham to sacrifice Isaac might come from Narvaez’s Ethic of Imagination whereas Abraham’s reluctance – “you must be puttin’ me on” – arose from his paternal instinct that was part of his Engagement Ethic.

In the next posts, I’m going to dig deeper into some of the findings of evolutionary psychology, which examines how these different systems converged in the minds of our paleolithic ancestors to create a set of hunter-gatherer values.  And as we move along humanity’s cognitive career, we’ll see how the different stages of social development led to the flowering of different sets of values, all of which interweave through our current system of thought.  Yes, we have come a long way from that primordial ooze.

[1] Weinberg, S. (2008). “Without God.” New York Review of Books, LV(14: September 25, 2008), 73-76.

[2] Kauffman, S. (2008). Reinventing the Sacred: A New View of Science, Reason, and Religion, New York: Basic Books, 86-7.

[3] Damasio, A. (1999). The Feeling of What Happens: Body and Emotion in the Making of Consciousness, New York: Harcourt Inc, 136-7.

[4] Cabanac, M., Cabanac, A. J., and Parent, A. (2009). “The emergence of consciousness in phylogeny.” Behavioural Brain Research(198: 2009), 267-272.

[5] Many ethologists, such as Sue Savage-Rumbaugh who has extensively studied great apes such as chimpanzees and bonobos, also claim most of these complex emotions for advanced primates.

[6] Narvaez, D. (2007). “Triune ethics: The neurobiological roots of our multiple moralities.” New Ideas in Psychology, 26(1), 95-119.

February 19, 2010

Animals Suffer? Lobotomize Them!

Posted in consciousness, Infinition, Scientific Revolution tagged , , , , , , , at 4:20 pm by Jeremy

Adam Shriver, no doubt driven by kindness and goodwill towards other animals, has written an op-ed piece in the New York Times today that is chilling in its implications.  Shriver notes the unnecessary and often cruel suffering that farm animals undergo as they’re being prepared for our supermarket freezers.  But then he offers hope of salvation from their suffering in a bizarre and frightening direction: apply genetic engineering to create new breeds of animals that don’t experience suffering all.  They would continue to experience pain, but a crucial part of their brain – the anterior cingulate cortex – would be genetically modified to stop functioning, and as a result they would no longer suffer from the consciousness of that pain.

At first sight, this might seem like a humane research direction, and I’m sure Shriver has nothing but the best intentions.  But this approach carries with it some sinister implications and augurs threateningly for a new and disturbing potential outcome of the intersection of neuroscience and genetic engineering.

Like so many stories on the subject of animal feelings, this one begins with René Descartes (1596-1650), the guy most famous for his declaration of “I think, therefore I am.”  Descartes applied the same logic to animals.  In his view, they didn’t think, therefore they weren’t.  Or, to be more precise, only humans, with their immortal souls, have the capability to think and feel.  By contrast, animals are mere instinctual machines, with no more capacity for feelings than vegetables.  “We should have no doubt at all,” he wrote, “that the irrational animals are automata.”[1]

Descartes’ view of animals as automata justified vivisection.

Strange as we may now view this, it was taken seriously at the time… to the great detriment of animals.  An observer at the time wrote of the gruesome torture administered to animals through vivisection, in the name of Descartes:

The [Cartesian] scientists administered beatings to dogs with perfect indifference and made fun of those who pitied the creatures as if they felt pain.  They said the animals were clocks; that the cries they emitted when struck were only the noise of a little spring that had been touched, but that the whole body was without feeling.  They nailed the poor animals up on boards by their four paws to vivisect them to see the circulation of the blood, which was a great subject of controversy.”[2]

Descartes had kicked off a long and powerful tradition which remains influential to this day.  It enjoyed its heyday in the behaviorism predominant in psychology throughout much of the 20th century, where the metaphor of “animal as machine” continued to be taken literally.  “Behaviorists tested the capacities of animals not through naturalistic observation but through highly controlled stimulus response experiments. Speculation about the subjective experiences or thought processes of animals seemed unscientific: animals didn’t think, they reacted.”[3]

Turns out, though, Descartes and the behaviorists were wrong.  Animals do suffer.  And over the past couple of decades, neuroscientists and ethologists have discovered multiple pathways of experience shared by both humans and other mammals.  Hormones such as oxytocin and vasopressin, which play crucial roles in our experience of love and bonding, turn out to have similar impacts in rodents and other mammals.[4] Evolutionary research shows that we share with other mammals “perhaps the most momentous achievement of evolution,”[5] the subjective experience of core consciousness.  This core consciousness is tied directly with a sense of self and of feelings.  As neuroscientist LeDoux puts it, “I will say that capacity to have feelings is directly tied to the capacity to be consciously aware of one’s self and the relation of oneself to the rest of the world.”[6]

As Shriver is no doubt well aware, the anterior cingulate cortex (“ACC”) plays a central part in this glorious process.  The ACC, in the words of one research team, “is primarily involved in assessing the salience of emotional and motivational information.”[7] The ACC acts like a super-sensitive, multi-faceted feedback mechanism for a creature’s moment-to-moment existence.  It monitors competing demands, detects unexpected changes in the environment and within the creature, funneling this information to the appropriate parts of the brain to prime a response.[8] In short, it has a key role in monitoring the self and directing attention.[9] In fact, it’s likely that without a fully functioning ACC, a creature would no longer have a self.  That’s probably why, in the experiments that Shriver discusses, rats without a functioning ACC withdraw their paws from a painfully hot area, but they don’t learn to avoid that area like normal rats.  Because they’ve lost a self to perceive the salience of an experience.

So Shriver’s proposed genetic engineering program would breed something never before seen on this earth: a mammal without a self.  Descartes, in his dualistic speculations, bizarrely proposed that the pineal gland might be the seat of the human soul.[10] Based on current neuroscience, if the soul of a creature has any one locus in the body that is an absolute prerequisite for its existence, that would be the ACC.

We now know that lobotomies destroy an individual’s sense of self.

We’ve gone down this path before, only with humans rather than animals.  In the first half of the twentieth century, neuroscientists found that frontal lobotomies seemed to miraculously cure symptoms of agitation and mental suffering.  Neurologist Walter Freeman promoted this procedure in the 1940’s and 1950’s, to the extent that by 1951, nearly 20,000 individuals had been lobotomized in the United States.[11] As we now know, as a tragic consequence of these procedures, these unfortunate victims lost not only their anxieties, but their sense of self.

I suggest that Shriver is proposing a 21st century, sanitized version of a lobotomy.  Only in this case, the lobotomy is already prefabricated through genetic engineering, and the zombie creatures formed would never even have had a self to lose.  In a ghastly irony, Shriver’s program would put Descartes right back in the driver’s seat.  Descartes said animals had no soul, no feelings.  He was proved wrong.  Now, Shriver wants to create a breed of animals that would make Descartes’ grotesque fantasy of “automata animals” come true.

I agree with Shriver that unnecessary farm animal suffering is a grievous aspect of our modern world, and that much more needs to be done to alleviate it.  But his proposal threatens an inner sanctum of nature which even we humans have not yet ventured to desecrate: a creature’s subjective sense of self.  We’ve trained, tormented, killed and eaten other animals from time immemorial; but we’ve never genetically engineered a creature to be a zombie.  Along with the powers brought to us by the discoveries of neuroscience and genetic engineering, we must establish a set of principles that incorporate a sense of what is sacred in the natural world… before we create a true Cartesian nightmare where all that’s left are we humans and our own artificially constructed environment, engineered for our consumption.

[1] Letter to Marin Mersenne, 13 July 1640, cited by Margulis, L., and Sagan, D. (1995/2000). What Is Life?, Berkeley: University of California Press, 37-8.

[2] Quoted by Masson, J. M., and McCarthy, S. (1995). When Elephants Weep: The Emotional Lives of Animals, New York: Delta, 18.

[3] Talbot, M. (2008). “Birdbrain: The woman behind the world’s chattiest parrots.” The New Yorker(May 12, 2008).

[4] de Waal, F. B. M. (2009). “Darwin’s last laugh.” Nature, 460(9 July 2009), 175.

[5] Edelman, G. M., and Tononi, G. (2000). A Universe of Consciousness: How Matter Becomes Imagination, New York: Basic Books, 211-12.

[6] LeDoux, J. (1996). The Emotional Brain: The Mysterious Underpinnings of Emotional Life, New York: Simon & Schuster, 125.

[7] Bush, G., Luu, P., and Posner, M. I. (2000). “Cognitive and emotional influences in anterior cingulate cortex.” Trends in Cognitive Sciences, 4(6: June 2000), 215-222.

[8] Kerns, J. G., Cohen, J. D., MacDonald, A. W. I., Cho, R. Y., Stenger, V. A., and Carter, C. S. (2004). “Anterior Cingulate Conflict Monitoring and Adjustments in Control.” Science, 303(13 February 2004), 1023-1026.

[9] Gallagher, H. L., and Frith, C. D. (2003). “Functional imaging of ‘theory of mind’.” Trends in Cognitive Sciences, 7(2: February 2003), 77-83.  Note: while this study focuses on ACC’s role in the human sense of self, (including “secondary self,”) the role of the ACC in forming a mammalian sense of core self would appear to homologous.

[10] For a detailed discussion, see “Descartes and the Pineal Gland,” Stanford Encyclopedia of Philosophy.

[11] Wikipedia entry on “Lobotomy.”