Social Neuroscience:

The Footprints of Phineas Gage

John F. Kihlstrom

University of California, Berkeley

Lives of great men all remind us

We can make our lives sublime

And, departing, leave behind us 

Footprints on the sands of time.

Henry Wadsworth Longfellow

"A Psalm of Life" (1838)

 

 

This conference marks an important milestone in the evolution of both neuroscience and the social sciences.

The social sciences got their start in the 19^th century, as August Comte invented sociology and foresaw the emergence of a "true final science" -- which he refused to call psychology, on the grounds that the psychology of his time was too metaphysical (Allport, 1954). His preferred term was la morale (nothing metaphysical about that!), a science of the individual combining cognition, emotion, and motivation with action. But he really meant psychology. Our metaphysical days are over (mostly), and modern psychology has links to both biology (through physiological psychology) and sociology (through social psychology). 

Neuroscience got its start, and its name, only in the early 1960s (Schmitt, Melnechuk, Quarton, & Adelman, 1966). Before that there was just neurology, a term dating from the 17^th century, neurophysiology (first appearing in English in 1859), and neuroanatomy (1900). As a biological discipline, neuroscience was initially organized into three branches: molecular and cellular neuroscience, concerned with neurons and other elementary structures of the nervous system -- the whole legacy of what Elliot Valenstein (2005) has called "the war of the soups and the sparks"; then there was systems neuroscience, concerned with how the various pieces of the nervous system connect up and interact with each other; and behavioral neuroscience, concerned with everything else -- but in particular with motor activity, basic biological motives such as hunger and thirst, and the operation of sensory mechanisms -- mostly without reference to mental states as such. 

But pretty quickly there began to emerge a fully integrative neuroscience (Gordon, 1990), concerned with making the connections between the micro and the macro, the laboratory and the clinic, and between neurobiology and psychology, followed by specialized neurosciences. First to make its appearance was cognitive neuroscience (M.S Gazzaniga, 1988), concerned with the neural bases of cognitive functions such as perception, attention, and memory (Michael I. Posner & DiGirolamo, 2000; M.I. Posner, Pea, & Volpe, 1982). Some practitioners of cognitive neuroscience defined "cognitive" broadly, so as to include emotional processes as well -- really, any internal state or process that intervened between stimulus and response. But there soon emerged a full-fledged affective neuroscience as well, running parallel to cognitive neuroscience, and intending to do for emotions and feelings what the cognitive neuroscientists had done for perception and attention (Davidson, Jackson, & Kalin, 2000; Panksepp, 1992, 1996, 1998). Now I have not yet seen the term used in print, but I can't help but think that a conative neuroscience, concerned with the neural basis of complex social motivation, not just survival motives like hunger, thirst, and sex, will arise shortly, completing the neuroscientific analysis of Kant's trilogy of mind (Hilgard, 1980).¹  

In addition, what began as a proposal for a social-cognitive neuropsychology (Klein & Kihlstrom, 1998; Klein, Loftus, & Kihlstrom, 1996), and then morphed into a social-cognitive neuroscience (Blakemore, Winston, & Frith, 2004; Heatherton, 2004; M.D. Lieberman, 2005; M.D Lieberman, 2007; Ochsner & Lieberman, 2001) has now begun to evolve into a full-fledged social neuroscience (Cacioppo & Berntson, 1992; Cacioppo, Berntson, & McClintock, 2000; Cacioppo et al., 2005; Cacioppo et al., 2006; Harmon-Jones & Devine, 2003). 

When Stan Klein and I suggested that social psychology take an interest in neuropsychology (the term I at least still prefer, because it puts equal emphasis on mind and brain), our idea was only that brain-damaged patients might provide an interesting vehicle for advancing social-psychological theory.

For example, amnesic patients do not remember the things they have done and experienced, but they seem to retain their identities, and even appreciate how their personalities may have changed with time and circumstance (Klein, Cosmides, & Costabile, 2003; Klein, Cosmides, Costabile, & Mei, 2002; Klein et al., 1996; Klein, Loftus, & Kihlstrom, 2002).  This finding provided multimethod confirmation of what we already believed from priming studies -- that episodic and semantic forms of self-knowledge are represented independently in memory (Klein & Loftus, 1993; Klein, Robertson, Gangi, & Loftus, 2007).

There are other examples.  Autistic children appear to lack a theory of mind, which prevents them from engaging in even elementary processes of person perception, inferring the attitudes and beliefs of other people (e.g., Simon Baron-Cohen, 1995; Tager-Flusberg, 2007).  And, although it seems that they only know their own minds (S. Baron-Cohen, 2005), they may even lack a theory of their own minds -- an essential component of the sense of self (Toichi et al., 2002; but see Klein, Chan, & Loftus, 1999).  Patients with frontal-lobe damage appear to have difficulties in self-regulation (Posner, Rothbart, Sheese, & Tang, 2007; Tucker, Luu, & Pribram, 1995) and self-awareness (Stuss, 1991).  Patients suffering from anosgognosia make strange causal attributions about their problems in memory, language, perception, and voluntary movement (McGlynn & Schacter, 1989; Prigatano & Schacter, 1991; Schacter, 1990).  Commisurotomy patients, too, explain their anomalous behaviors in peculiar ways (Gazzaniga, 2000; Gazzaniga et al., 1996).  Prosopagnosics appear to have a specific deficit in recognizing faces (Bodamer, 1947; Damasio, Damasio, & Van Hoesen, 1982), which draws attention to the other information available for this purpose -- the sound of their voice, their bodies, their gait and other gestures -- and forces us to ask deeper questions about nonverbal behavior.  There is also a whole set of "delusional misidentification syndromes", such as Capgras syndrome (the belief that a familiar person has been replaced by an impostor) and reduplicative paramnesia (the belief that a familiar person has been duplicated), which raise fundamental questions concerning the cognitive basis of close social relationships (Feinberg, 2009).

Viewed from a different perspective, though, brain-damaged patients raise interesting questions concerning interpersonal processes. Consider, for example the role of memory in social relations. In a singles bar, the stereotypical pick-up line is "Come here often?" -- which is essentially a question about memory. We break the ice with new acquaintances by sharing our memories, whether it's our earliest recollections of childhood, where we were on 9/11, or what we did on our summer vacation. When we become friends with a person, to the extent that we become friends, we come to share their memories. And when the friendship breaks up, we suffer a kind of anterograde amnesia for that person's life. Similarly, social groups gain some of their cohesion by the collective memories shared by group members, but not by members of outgroups. Shared memories are part of the glue that binds marriages together. And how many marital disputes are over memory, including forgotten anniversaries, slights and insults that simply cannot be forgotten, and conflicting mental representations of the past? ("No I didn't!" "Yes you did!") So, in the absence of conscious recollection, how do people like H.M. maintain social relations, and how do people maintain social relations with them -- or, put another way, what kinds of social relations can you have without memory? 

But I take it that social neuroscience is about more than expanding the subject pool beyond college sophomores and people waiting in airport departure lounges. And, frankly, it's more than identifying the neural bases of social behavior, because that's the historical agenda of physiological psychology - -which had been doing just fine, thank you very much, for many years before neuroscience was a gleam in anyone's eye (Milner, 1970; Morgan, 1943; Teitelbaum, 1967). Rather, social neuroscience seems to represent a new point of view about how to do social science -- just as cognitive neuroscience presented itself as a new way of doing cognitive psychology, by looking at the brain as well as the mind. 

When cognitive neuroscience began, it was little more than an umbrella term, collecting all the individual disciplines interested in brain and behavior -- "the neurosciences", like "the physical sciences" or "the social sciences" (Quarton, Melnechuk, & Schmitt, 1967; Schmitt, 1970a, 1970b). If you pick up Mike Gazzaniga's encyclopedic followup to the Neuroscience Study Program volumes (M.S. Gazzaniga, 1995), the first thing you notice is its title: The Cognitive Neurosciences, plural; and when you look at the table of contents, you see large sections devoted to neural plasticity and development, sensory and motor systems, attention, memory, language, thought, imagery, consciousness, even emotion.  There is no mention of social psychology, but even more important there is also no attempt to characterize cognitive neuroscience, singular, as a field as such. There's just the first sentence of the preface: "At some point in the future, cognitive neuroscience will be able to describe the algorithms that drive structural neural elements into the physiological activity that results in perception, cognition, and perhaps even consciousness". (p. xiii).  A somewhat more tractable version of the definition appeared in the 3rd edition.

But this can't be right, because the goal of determining the biological substrates of cognition (and other aspects of mental life and behavior) has historically been the mission of physiological psychology (e.g., Morgan, 1943; Teitelbaum, 1967). 

In their undergraduate textbook on Biological Psychology, Rosenzweig and his colleagues described a broader subfield that considers genetics and evolution as well as anatomy and physiology.  There should be a distinctive mission, or a distinctive approach, to justify the new moniker.

Gazzaniga and his colleagues did better in their undergraduate textbook, where they pointed to how "the disciplines of cognitive psychology, behavioral neurology, and neuroscience now feed off each other, contributing a new view to the understanding of the mechanisms of the human mind" (M.S. Gazzaniga, Ivry, & Mangun, 1998, p. xiii). They invoked Marr's (1982) hierarchical analysis of information processing: a computational level that operates on input representations to generate output representations, an algorithmic level that specifies the processes to be performed at the computational level; and an implementational level that embodies the algorithms in a physical system. But they balked at Marr's assumption that the computational and algorithmic levels could be understood without reference to the implementational level. "Any computational theory", they asserted, "must be sensitive to the real biology of the nervous system, constrained by how the brain actually works" (p. 20). 

Similarly, Kosslyn and Koenig (1992, p. 4) portrayed the "dry mind" approach of traditional cognitive psychology and cognitive science as similar to "the attempt to understand the properties and uses of a building independent of the materials used to construct it". This was in contrast to the "wet mind" approach of "the new cognitive neuroscience": "the kinds of designs that are feasible depend on the nature of the materials". By analogy, "a description of mental events is a description of brain function, and facts about the brain are needed to characterize these events".

Along the same lines, Ochsner and Kosslyn (1999, p. 324), illustrated the cognitive neuroscience approach with "the cognitive neuroscience triangle" (p. 325), with cognitive abilities at the apex, and computation and neuroscience at the bottom corners. As they put it, "Abilities is (sic) at the top because that is what one is trying, ultimately, to explain, and neuroscience and computation are at the bottom because the explanations rest on conceptions of how the brain computes" (p. 324). Explanations of cognitive abilities rest on conceptions of how the brain computes. This is what some cognitive neuroscientists mean when they say that psychological theories are constrained by neuroscientific evidence. The idea is that evidence about brain structure and function will somehow determine which theories of cognitive function are right, and which are wrong. 

What I have called the rhetoric of constraint has been echoed by some social neuroscientists as well. For example, Cacioppo and Berntson (1992) wrote that "knowledge of the body and brain can usefully constrain and inspire concepts and theories of psychological function..." (p. 1025). Similarly, Ochsner and Lieberman (2001, p. 726) argued that "cognitive psychology underwent [a] transformation as data about the brain began to be used to constrain theories about the cognitive processes underlying memory, attention, and vision, among other topics" -- with the implication that social psychology would undergo a similar transformation as data about the brain began to be used to constrain theories about the cognitive processes underlying social interaction.  And Harmon-Jones and Devine (2003, p. 589) discussed "the power of neuroscientific methods to address processes and mechanisms that would not be possible with the traditional methodological tools of the social psychologist".  The implication of all three quotations is that social psychology will be a better psychology for taking neuroscientific evidence into account.

Now Ochsner and Lieberman (Ochsner & Lieberman, 2001) are surely right that social psychology "gained greater conceptual and explanatory power" (p. 726) as it stepped down from the behavioral level to the cognitive level -- thus replacing the objective situation of classical experimental social psychology with the subjectively perceived situation of modern cognitive social psychology. But it is not at all clear that either cognitive or social psychology gain additional "conceptual and explanatory power" by taking a further step down from the cognitive to the neural level of analysis. 

A softer version of the rhetoric of constraint is found in the writings of Daniel Goleman, who has recently done for social intelligence (Cantor & Kihlstrom, 1987, 1989; Kihlstrom & Cantor, 2000) (see also Landy, 2006) what he did earlier for emotional intelligence (Goleman, 1995; Salovey & Mayer, 1989). For Goleman, the study and application of social intelligence -- which he characterizes as having been a "scientific backwater" (p. 330) up to now, will be reinvigorated by the ongoing discovery of mirror neurons and other aspects of a social brain hard-wired by evolution to "orchestrate our activities as we relate to other people" (p. 324). Exactly how that is supposed to happen isn't clear, but Goleman insists that knowledge of brain function is going to revolutionize our understanding of social intelligence, and of social behavior in general. Still, it has to be admitted that the revolution in economics, which Goleman takes to be an inspiration for social psychology, didn't come from neuroimaging, but from Herb Simon (Simon, 1955), and Kahneman and Tversky (Tversky & Kahneman, 1974), and others like them, armed only with field observation, interview protocols, and paper-and-pencil questionnaires -- and there are Nobel Prizes to prove it. 

To some extent, the rhetoric of constraint is a reaction to a kind of functionalism that characterized classical cognitive psychology and cognitive science -- the idea that the mind was software that could be implemented by any sufficiently complex physical system -- whether a brain, or a silicon chip, or a bunch of beer cans connected by string. This functionalism lies at the heart of what John Searle has called "strong artificial intelligence", which asserts that a machine that could perform the same functions as a mind would have the same mental states as minds do (J. Searle, 1980). And it also lies at the heart of the computational model of the mind, which asserts that the mental processes that generate mental states can be thought of as algorithms that operate on symbolic representations. And it's just this kind of computational functionalism that drives some cognitive scientists (like Searle) crazy. Against the Marvin Minskys of the world, who assume that the brain is a machine made of meat, they argue that brains are not just machines, or at any rate that they are very special machines, and that mental life has the properties it does precisely because it's produced by brains. Put another way, our mental states and processes are the way they are because our brains are the way they are. 

But it is one thing to assume that mental life is a product of brain activity, and another thing entirely to assert that knowledge of how the brain works constrains the kinds of theories we can have about mental life. In fact, it appears that precisely the reverse is true: psychological theory constrains the interpretation of neuroscientific data. I've discussed this issue elsewhere (Kihlstrom, 2006) (see also http://socrates.berkeley.edu/~kihlstrm/SPSPDialogue06.htm), and I won't belabor the point now, except to reprise my favorite example: the amnesic patient H.M., who put us on the road toward understanding the role of the hippocampus in memory. But what exactly is that role? The fact is, our interpretation of H.M.'s amnesia, and thus of hippocampal function, has changed as our conceptual understanding of memory has changed. First, H.M. was thought to have lost his recent memory (Scoville & Milner, 1957); then to have lost long-term but not short-term memory (Atkinson & Shiffrin, 1968); then to have suffered a retrieval rather than an encoding failure (Warrington & Weiskrantz, 1970); then to be capable of shallow but not deep processing (Butters & Cermak, 1975); then to have lost declarative but not procedural memory (N. J. Cohen & Squire, 1980); then episodic but not semantic memory (D.L. Schacter & E. Tulving, 1982; D. L. Schacter & E. Tulving, 1982); then explicit but not implicit memory (Graf & Schacter, 1985; Schacter, 1987); then declarative but not nondeclarative memory (Larry R. Squire & Knowlton, 1994); and now, most recently, relational but not non-relational memory (N.J. Cohen et al., 1999). Here, clearly, neuroscientific data hasn't done much constraining: the psychological interpretation of H.M.'s brain damage, and its implication for cognitive theory, changed almost wantonly, as theoretical fashions changed in psychology, while the neural evidence stayed quite constant. 

Look at it another way. Suppose you had no idea where H.M. had sustained his brain damage. You just learned about this patient who couldn't seem to remember recent events. However, further, careful testing, of H.M. and of other patients like him, employing the paradigms of cognitive psychology, revealed that he suffered a specific impairment of explicit memory that spared implicit memory. The conclusion that there are two expressions of memory, explicit and implicit, and that they are dissociable, might be (and indeed I think it is) a substantial advance in cognitive theory. But it's an advance that comes from behavioral data -- from how H.M. and his confreres performed on tests of free recall, stem-completion, pursuit-rotor learning, and the like. It doesn't matter where his brain damage is.

There seems to be nothing about the anatomy and physiology of the medial temporal lobe that dictates that it should be involved in conscious recollection, as opposed to emotion or mental imagery. If you knew that H.M. dissociated explicit and implicit memory, and then found out that his brain damage was in the amygdala instead of the hippocampus, you'd start thinking that the amygdala had something to do with conscious recollection. You wouldn't say "Oh, no, that can't be right, because the amygdala is too medial, or too anterior to be involved in memory; or the particular neurons that make up the amygdala, and the neurotransmitters that they use, aren't right for memory processing. You'd better take another look at that structural MRI". Instead, you'd say "Huh! OK, that's interesting, maybe the amygdala has something to do with conscious recollection" -- and then, perhaps, you'd say "Gee, I wonder what the hippocampus does".

But if you're interested in the neural bases of memory, then neuroscientific evidence is obviously critical. You can start with the hippocampus, and then try to figure out whether any of the other structures to which it's connected also play a role in memory. And, in that way, you can determine that the amygdala doesn't play a role in memory after all, but that the perirhinal and parahippocampal areas are also critical -- not just because they pass sensory information to the hippocampus, which would be trivial, but because they have some memory functions independent of the hippocampus (L. R. Squire & Zola-Morgan, 1991). And then you conclude that there's a whole system of medial-temporal lobe structures that are involved in various aspects of memory. 

And that's the way it works everywhere else we look in cognitive neuroscience (Coltheart, 2006a, 2006b) -- and, for that matter, in psychology more broadly (Hatfield, 1988, 2000). Once we have a good description of some process at the psychological level of analysis, then we try to determine how the brain does it, and the presence of a valid psychological theory allows us to make valid interpretations of what we see at the neural level. If the psychological analysis is wrong, the analysis of neural function will be wrong as well. That's because cognitive and social neuroscience depend on cognitive and social psychology; but cognitive and social psychology don't depend on neuroscience. The constraints go down, not up. As Randy Gallistel, a cognitive neuroscientist if ever there was one, has put it: "An analysis at the behavioral level lays the foundation for an analysis at the neural level. Without this foundation, there can be no meaningful contribution from the neural level" (Gallistel, 1999, p. 843). Or, as I like to put it, psychology without neuroscience is still psychology, but neuroscience without psychology is just neuroscience.² 

What cognitive and social neuroscience can do, is explicitly link cognition and social interaction with the brain. Stan Klein and I began our paper with the observation that "For a very long time psychology thought it could get along without looking at the brain" (Klein & Kihlstrom, 1998, p. 228). Everybody understood that the mind is what the brain does, but very few people tried to figure out the details. Partly the reasons were ideological: first there was the Skinnerian "black box" doctrine of the empty organism, and later the computational functionalist notion of the brain as a universal Turing machine -- which, if you think about it, can be just a dressed up form of behaviorism. But it wasn't just ideology. As Posner and DiGirolamo (2000) noted, Lashley's doctrine of mass action and equipotentiality reinforced the idea that cognitive processes weren't, and thus couldn't, be localized. 

The situation in 1967, when I took introductory psychology, was pretty representative. Here's a depiction of functional localization in my textbook, by Morgan and King (1966) -- both of whom were distinguished physiological psychologists (Morgan will be well-known to Texans of a certain age). When it came to the brain, we were taught the landmarks that separated the various lobes, and we were also taught that there were small areas of each lobe devoted to particular elementary functions: motor control in the frontal lobe, touch in the parietal, audition in the temporal, and vision in the occipital. The rest was "association cortex" (p. 710) -- with the anterior portion perhaps specialized for thinking and problem-solving, and the posterior portion having to do with complex perceptual functions, and "symbolic speech" (p. 713) in Broca's and Wernicke's areas. It all pretty much followed from traditional stimulus-response associationism: learning, thinking, and all the rest were mediated by associations, and associations were formed, and stored, in the association cortex as a whole. 

The specialized areas for speech and language, of course, were the cracks in the dike, and pretty soon, this scheme began to break up. Inspired by Chomsky's idea that there is a language organ, Fodor (1983) postulated a set of mental modules interposed between transducers that make representations of sensory stimulation available to other systems, and central systems that form inferences and beliefs. These modules have a number of interesting properties, but for our purposes three are paramount. First, they are domain-specific -- there might be a visual module for the analysis of three-dimensional spatial relations, which applies principles like linear perspective to create the perception of depth. Second, they are informationally encapsulated, meaning that their operations are not affected by what's going on elsewhere in the system -- which is why we still see the Ponzo illusion even after we've understood how it works. Third, and most important for present purposes, they are associated with a fixed neural architecture -- there's some part of the brain that has the neural machinery that implements the module's activity. 

While it's the goal of cognitive psychology (and cognitive science more broadly) to work out how these modules work at the psychological level of analysis, the defining agenda of cognitive neuroscience is to identify the neural correlates of these modules in some centers, or systems of centers, in the brain. Without something like the doctrine of modularity, cognitive neuroscience doesn't make any sense. If all mental life were just a matter of associations formed by a general-purpose information-processor -- or, for that matter, systems of productions operating on symbolic representations (Anderson, 1976), or even patterns of activations across a connectionist network (McClelland & Rumelhart, 1986; Rumelhart & McClelland, 1986) -- we wouldn't be interested in the neural bases of different mental functions, and we wouldn't need any neuroscience beyond molecular and cellular biology. 

Of course, the idea of functional specialization has its origins in phrenology (Finger, 1994; Gross, 1998a) -- although it was foreshadowed in the work of Emanuel Swedenborg (Swedenborg, 1740/1845-1846), who dabbled in anatomy before he became a Christian mystic (Gross, 1998b). But for the most part, prior to the 19^th century, the brain was considered to be a single organ. But as is well known, first Gall and then Spurzheim, both of whom were distinguished neuroanatomists, identified some three dozen separate mental faculties, including propensities like secretiveness and acquisitiveness, sentiments like cautiousness and self-esteem, perceptive abilities like size and weight, and reflective abilities such as comparison and causality -- each localized in a different part of cerebral cortex, as revealed by bumps and depressions in the skull (Gross, 1998c). 

The phrenologists' evidence was terrible, of course, and their assertions were vigorously challenged by Pierre Flourens and others, who argued for an early version of the law of mass action. But the tide turned in 1861, when Paul Broca correlated "motor" (expressive) aphasia with damage to the left frontal lobe -- Stanley Finger (1994, p. 376) calls it "the revolution of 1861". Modern cognitive neuroscience has now gone on to identify dozens of brain centers for specific functions. Here is a map, published in the New York Times seven years ago (March 14, 2000), showing the locations of a host of centers for things like exact versus approximate mathematical computations, the perception of speed and motion, and the like. The general-purpose association cortex was already getting carved up pretty quickly, as cognitive neuroscience advanced its agenda of identifying brain systems associated with mental systems. 

Of course, none of these areas had much or anything to do with social behavior per se. By contrast, one of the things that has struck me about the classical phrenologists' map is how social many of their faculties were. While all the phrenological faculties represented "higher" mental functions, as opposed to "lower" sensory and motor abilities, more than half of the three-dozen or so faculties listed by Spurzheim (1834) were affective as opposed to intellectual in nature, and almost half of them are legitimate topics for personality and social psychology. Consider these faculties, from the 37 listed in Spurzheim's final system (the numbers reflect Spurzheim's taxonomy): 

That's 17 out of 37 right there. You could even make a case for 

Social neuroscience really begins here. 

And here's where Phineas Gage comes in (you were perhaps wondering when I was going to get around to Gage?).³ We all know the basic story (Malcolm Macmillan, 2000; Macmillan, 1986) (see also Macmillan's "Phineas Gage" website, http://www.deakin.edu.au/hmnbs/psychology/gagepage/index.php):

Cavendish, Vermont, September 13, 1848, 4:30 PM. This railway construction foreman, while placing explosives in some rock, accidentally blasted his tamping iron through his head, entering under his left cheekbone and exiting from the top of his skull, destroying most of his left frontal lobe. Treated by John Martyn Harlow, a local physician, Gage survived, eventually dying in San Francisco on May 21, 1860 (Fred Gage, the distinguished neuroscientist at the Salk Institute and pioneer in the study of neurogenesis, is a distant relative). 

Medical interest in the case initially focused on the fact that Gage lived at all -- not to mention that he continued to function reasonably well. But most modern authorities, such as Hanna and Tony Damasio (A. R. Damasio, 1994; H. Damasio et al., 1994) focus on the claim that, after his accident, "Gage was no longer Gage". Or, as some wag wrote (M. Macmillan, 2000, p. 42):

A moral man, Phineas Gage,

Tamping powder down holes for his wage,

Blew the last of his probes

Through his two frontal lobes;

Now he drinks, swears, and flies in a rage.

Of course, we have to take some of this with a grain of salt. As Malcolm Macmillan has cogently demonstrated, many modern commentators exaggerate the extent of Gage's personality change, perhaps engaging in a kind of retrospective reconstruction based on what we now know, or think we do, about the role of the frontal cortex in self-regulation. 

What is not fully appreciated is that, more than a decade before Broca and Wernicke, the Gage case played a role in the debate over phrenology and localization of function (Malcolm Macmillan, 2000; Macmillan, 1986) (see also Barker, 1995). John Martyn Harlow's initial (1848 and 1849) reports of the case merely emphasized the fact that Gage had survived. An 1850 report on the case by Henry J. Bigelow, the Harvard professor of surgery who also examined Gage and was eventually to acquire his skull and tamping iron for what is now the Countway Medical Library, called it "the most remarkable history of injury to the brain which has been recorded" to date -- remarkable because Gage survived at all, much less continued to function. All these accounts could be interpreted as consistent with Flourens' holistic view of the brain -- that you could lose a lot of tissue and still function just fine, thank you very much. 

But already in 1848, Harlow was hinting that while Gage's intellectual capacities were unaffected by the accident, he had observed changes in his "mental manifestations" -- a piece of phrenological jargon that referred to the affective (and social) as opposed to the intellectual faculties. In 1851, an anonymous article in the American Phrenological Journal insisted that Gage was, in fact, changed by his accident. "Before the injury he was quiet and respectful." But "after the man recovered... he was gross, profane, coarse, and vulgar, to such a degree that his society was intolerable to decent people". Harlow himself, in his final report of 1868, described the "mental manifestations" in some detail, with particular respect to the "equilibrium... between his intellectual faculties and his animal propensities". Nelson Sizer, a prominent American proponent of phrenology (and probably the author of the 1851 APJ article), concluded that the tamping iron had passed out Gage's head "in the neighborhood of Benevolence and the front part of Veneration" (Malcolm Macmillan, 2000, p. 350).⁴ This was 10 years before Broca refuted Flourens. Unfortunately, Gage's brain (as opposed to his skull) was not available for examination, or Harlow and Bigelow might have beaten Broca to the punch, and Gage, not Tan, would have been the milestone demonstration of cerebral localization. Still, just as H.M. became the index case for the new cognitive neuroscience, so Phineas Gage becomes the index case for our new social neuroscience. 

If, as I argue, the defining feature of cognitive neuroscience is the search for dedicated cognitive modules in the brain, then the defining feature of social neuroscience is the search for dedicated social modules. The phrenologists had some ideas about what these might be, and so have some more recent social scientists. 

Howard Gardner (1983) explicitly cited Gage as evidence for an interpersonal form of intelligence, defined as "the ability to notice and make distinctions among other individuals", and isolable by brain damage from other intellectual abilities. (Gardner also proposed an intrapersonal form of intelligence, defined as the ability to gain access to one's own internal, emotional life".)

Taylor and Cadet (1989) offered a more differentiated view of the neurological basis of social intelligence, suggesting that three different "social brain subsystems" were involved: a balanced/integrated cortical subsystem that employs long-term memory to make complex social judgments; a frontal-dominant subsystem that organizes and generates social behaviors; and a limbic-dominant subsystem that organizes and generates emotional responses.

Based on his analyses of autistic children, Simon Baron-Cohen (1995) suggested that the capacity for mindreading -- by which he really means a capacity for social cognition -- is based on four cognitive modules, each presumably associated with a separate brain system, impairments in which presumably cause the "mindblindness" characteristic of autism.

An even more differentiated view has been offered by Daniel Goleman (2006). As he imagines it, the social brain is not a discrete clump of tissue, like MacLean's (1970) "reptilian brain", or even a proximate cluster of structures, like the limbic system. Rather, the social brain is an extensive network of neural modules, each dedicated to a particular aspect of social interaction.

Modularity is all the rage now in both cognitive and social neuroscience (Pinker, 1997), but even Fodor (2000) has expressed doubt about what he has called Massive Modularity -- the idea that the mind, and thus the brain, is nothing but a collection of a vast number of modules, each dedicated to performing a different cognitive activity. 

In the first place, there has to be a mechanism for general-purpose information processing -- the role once assigned to association cortex. This is because we can solve problems other than those that confronted our ancestors on the African savannah in the Pleistocene Era -- like how to jury-rig carbon-dioxide scrubbers to keep the crew of Apollo XIII alive after their command module lost power and heat. To take another example: the modern phrenological head locates a brain system for the semantic priming of visual words: but it seems extremely unlikely that evolution produced a specialized brain system for processing visual words, for the simple reason that words were only invented 6,000 years ago, and the brain hasn't yet had enough time to evolve one.

The greatest gift of evolution was not a mental toolbox of dedicated modules: it was language, consciousness (which gave us something to talk about), and the general intelligence needed to solve problems other than those posed by the Environment of Early Adaptation. In  fact, on the assumption that our cognitive modules were adapted to the conditions of the EEA, it seems likely that it was our capacity for general intelligence, and general problem-solving ability, that permitted us to migrate out of the savannah in the first place, so that we now have a permanent presence on every continent (including Antarctica), and in every climate (including outer space).  

We don't simply adapt to the environment.  We also adapt the environment to us.  And that adaptation is enabled by consciousness, language, and most of all, our high general intelligence -- all, arguably, products of biological evolution; but all, certainly, the means by which cultural evolution transcends biological evolution.    And to the extent that social behavior is mediated by a general-purpose information-processing system, the project of identifying specific neural correlates of social behavior will fail, because the models and methods of social neuroscience are geared toward identifying domain-specific modules. 

So if the brain isn't just an equipotential blank slate, neither is it composed exclusively of dedicated mental modules. What's needed is a system that lies somewhere between Gardner's proposal for a single module for "interpersonal intelligence" and Goleman's "far-flung neural networks" (p. 324) -- a kind of "basic level" analysis that encompasses a limited number of dedicated modules, but still leaves ample neural space for general problem-solving. 

One such proposal comes from Ray Jackendoff (1992; 2007; 1994), a cognitive scientist much influenced by Chomsky and Fodor, who has argued since 1992 that certain aspects of social cognition are modular in nature.⁵ For example, he has argued that because social organization is unrelated to perceptual structure -- that is to say, the interpersonal meanings assigned to objects and events are not highly correlated with their physical attributes -- the same modules that process perceptual information cannot process information relating to social stimuli. 

What kinds of social information-processing modules might there be? Based on considerations of specialized input capacities, Jackendoff has suggested that there might be dedicated modules for face and voice recognition, affect detection, and intentionality. Based on considerations of developmental priority, he has suggested that children have an innate capacity to distinguish between animate and inanimate objects, and to learn proper names --that is, to think about individual people as such. And based on the work of Alan Fiske (son of Donald, brother of Susan), he has suggested that there are modules dedicated to processing such universal cultural parameters as kinship, ingroup-outgroup distinctions, social dominance, ownership and property rights, social roles, and group rituals. Now, Jackendoff doesn't think that the Liturgy of the Eucharist is hard-wired into anybody's head. But he does think that we come into the world innately equipped to pick up on such things -- just as we come into the world innately equipped to pick up Russian, if that's the language our parents happen to speak. And that innate equipment comes as a set of brain modules.

Without commenting on the specifics, Jackendoff's proposal strikes me as hitting just about the right level of analysis. Certainly there would be good reasons for thinking that evolution might have produced something like a face-perception module, allowing the easy recognition of that most social of stimuli. And sure enough, based on neuropsychological analyses of prosopagnosic patients, as well as neuroimaging studies of neurologically intact subjects, Nancy Kanwisher and her colleagues seem to have identified just such a module in the fusiform gyrus (Kanwisher, McDermott, & Chun, 1997) -- along with an area in the occipito-temporal cortex specialized for the perception of body parts (Downing, Jiang, Shuman, & Kanwisher, 2001), and another one at the temporo-parietal junction specialized for the theory of mind (Saxe & Kanwisher, 2003). 

And since then, social neuroscience has proceeded apace. In a recent review, Matt Lieberman (2007) has identified some 21 different social-cognitive functions that have been localized through brain-imaging studies -- some automatic and others controlled, some directed toward internal mental space, others directed towards external appearance and behavior.

Lieberman (2007) has suggested that the distinction between externally and internally focused social cognition is an organizing principle that emerges only from a neuroscientific analysis, on the ground that internally focused modules tend to be located in medial portions of frontoparietal cortex, while externally focused modules tend to be located in lateral portions of frontotemporoparietal cortex.  If so, that would contradict the position, taken in this paper, that neuroscientific findings do not, and cannot, constrain psychological theory.  Lieberman's distinction may be the exception that tests the rule.  On the other hand, the internal-external distinction is similar to other distinctions, already well established in nonsocial cognition, between perception-based and meaning-based knowledge (Anderson, 1995; Paivio, 1986), and between perceptually driven and conceptually driven processing (Roediger & McDermott, 1993), and it would not be surprising that a similar distinction held in the social domain as well.  The separate neural representation of perceptual and conceptual social-cognitive processes implies that they can be dissociated; but behavioral evidence from priming studies has already established that perceptually driven and conceptually driven processes can be dissociated from each other (Blaxton, 1989).

Of course, some of these findings are controversial. To take just one example, the idea that there is a brain module dedicated to identifying faces is one of the most appealing "just so" stories of evolutionary psychology, but establishing the existence of such a module turns out to be no trivial matter. For one thing, Isabel Gauthier, Mike Tarr, and their colleagues have produced quite compelling evidence that the same "fusiform face area" (FFA) that is activated in face recognition is also activated when experts recognize all sorts of other objects, including greebles. And that prosopagnosic patients, who appear to have a specific deficit in categorizing faces, also have problems categorizing snowflakes (e.g., Gauthier, Behrmann, & Tarr, 1999; Gauthier & Tarr, 1997; Gauthier, Tarr, Anderson, Skudlarski, & Gore, 1999; Tarr & Gauthier, 2000). So, perhaps, the FFA may not be a face-specific area after all, but rather a "flexible fusiform area" (Tarr & Gauthier, 2000) that is specialized for recognition at subordinate levels of categorization -- of which face recognition is a particularly good, and evolutionarily primeval, example.

To take another example, consider the self-reference effect (SRE), first observed in the "depth of processing" (DOP) paradigm, in which making self-referent judgments about words leads to an advantage in memory over other semantic judgments.  Based on the standard interpretation of the DOP effect, Rogers and his colleagues concluded that the self is a highly elaborate knowledge structure (Rogers, Kuiper, & Kirker, 1977). 

And based on this interpretation, Craik and his colleagues (Craik, Moroz, Moscovich, Stuss, Winocur, Tulving, et al., 1999) employed the SRE in an experiment that suggested that self-referent processing was performed by a neural system located in medial prefrontal cortex (mPFC).  

But it has long been known that the self-reference effect is duplicated when subjects are asked to make other-referent judgments concerning individuals that they know well (e.g., Keenan & Baillet, 1980).  

And, as it turns out, a properly controlled other-referent task activates the same cortical areas as does the standard self-reference task (Ochsner, Beer, et al., 2005; for a review, see Gillihan & Farah, 2005).  So, it might be the case that making person-referent judgments is mediated by a system in mPFC, but that the same module makes judgments about both self and others.  

Unfortunately, it has also long been known that the self-reference effect has nothing to do with the self: the advantage in memory produced by self-referent processing is wholly an artifact of organizational activity (Klein & Kihlstrom, 1986).  

In the standard SRE experiment, the semantic processing task employs a different sentence frame for every item; but for the self-referent task, the question is always the same: is the item self-descriptive or not?  So, self-referent processing encourages subjects to sort items into two categories -- those that are self-referent and those that are not. The upshot is that the typical self-reference task involves organizational activity, while the typical semantic  task does not.  When Stan Klein cleverly unconfounded self-reference and organization, he discovered that literally all the variance in recall was accounted for by organizational activity, with none left over for self-reference.  So, the activation of mPFC by self-referent processing may have nothing to do with social cognition at all, but may simply reflect organizational activity of any sort. 

To my knowledge, nobody has yet done an imaging study to identify the neural module serving organizational activity in memory.  But the larger point is that the psychology has to be right or the neuroscience will be wrong: the constraints go down, not up.

Gauthier's proposal remains controversial (for a flavor of the debate see Tarr & Cheng, 2003; McKone, Kanwisher, & Duchaine, 2007), and I suppose that it is possible that snowflake-recognition co-opts a brain module that originally evolved for face-recognition. But the larger point is that the accurate assignment of neural function depends not so much on the sensitivity of the magnet, but on the nature of the task that the subject performs while in the machine. If you want to know what the FFA really does, the psychology has to be right; nothing about neuroscience qua neuroscience is going to resolve these issues. 

The first glimmers of social neuroscience were pretty exclusively psychological in nature, having their origins in social psychophysiology and cognitive neuropsychology. And based on the research being presented at this conference, social neuroscience is still pretty psychological in nature. Maybe that's the way it has to be. Consider the three basic levels at which we can explain behavior. Psychologists explain the behavior of individual organisms in terms of their mental states. We explain someone's suicide in such terms as his belief that he is worthless, his feelings of depression, or his lack of desire to live. That's what psychologists do. 

A biologist, by contrast, would explain the same behavior in terms of some biological mechanism -- a genetic disposition, perhaps, or an anomalous neurotransmitter. 

And a sociologist or anthropologist would explain the same behavior in terms of some structure or process that resides outside the individual's mind or brain -- the hothouse atmosphere of a cult, for example, in the case of the mass suicide at Jonestown; or a culture dominated by Emperor-worship, in the case of Japanese kamikaze pilots in World War II. 

Of course, from a strictly psychological point of view both the neurobiological and the sociocultural effects on behavior are mediated through psychology. Diminished serotonin levels, perhaps generated by a particular genetic polymorphism, make people feel depressed and think about suicide; and the cult of the Emperor, or membership in the People's Temple, might make people want to sacrifice themselves for the cause.

I take it that the goal of cognitive (and affective, and conative) neuroscience is to link the psychological level of analysis to the neurobiological level; similarly, it's one goal of social psychology to link the psychological and sociocultural levels of analysis. And social neuroscience can serve to link the sociocultural level of analysis through the psychological level all the way down to the neurobiological. But it seems to me that the neuroscientific approach has the potential to extend beyond individual psychology, to encompass other social sciences as well.

We see this trend looming on the horizon in such new fields as neuroeconomics (Glimcher, 2003) and neuroethics (Farah, 2005; M.S. Gazzaniga, 2005) -- not to mention inroads of neuroscience into political science (Westen, 2007; Wexler, 2006). Also on the side of applied social neuroscience are emerging fields like neuromarketing (McClure et al., 2004) and neurolaw (Rosen, 2007). There's even a neurophilosophy (P. S. Churchland, 1986) and a neurotheology (McKinney, 1994).

Now much of this work still looks a lot like psychology, focused as it is at the level of individual minds and brains. But it is possible that in the future we will begin to see work that is both neuroscientific and distinctively anthropological or sociological in nature. Of course, physical anthropology always implied an interest in neuroscience, and there are a number of anthropologists engaged in a kind of comparative neuroanatomy among primate species, as well as a paleoneurology focused on hominids. But that's pretty much pure evolutionary biology, and it might be really interesting to get the cultural anthropologists involved, looking at the neural underpinnings of culture (Rilling, 2007). Similarly, sociologists might get interested in looking at the neural underpinnings of processes, such as social identification (Berreby, 2005), that emerge at the level of the group, organization, and institution. If E.O. Wilson (1998) is right that certain aspects of group behavior have evolved through natural selection and are encoded in the genes, they should be encoded in the brain as well -- perhaps we should call it socioneurobiology. 

The danger in all of this is reductionism -- not so much the everyday causal reductionism implied by the axiom that brain activity is the source of mind and behavior, but in particular the eliminative materialism, sometimes disguised as intertheoretic reductionism, which asserts that the language of psychology and the other social sciences is at best an obsolete folk-science, and at worst misleading, illegitimate, and outright false. In this view, psychological concepts such as belief, desire, feeling, and the like -- have the same ontological status as vital essence, the ether, and phlogiston -- which is to say they're nonexistent, and should be replaced by the concepts of neuroscience (P.M. Churchland, 1981; Paul M. Churchland, 1995; P. M. Churchland & Churchland, 1991; Paul M. Churchland & Churchland, 1998; P. S. Churchland, 1986; Stich, 1983). 

You get a sense of what eliminative reductionism is all about when Pat says to Paul, after a particularly hard day at the office,

"Paul, don't speak to me, my serotonin levels have hit bottom, my brain is awash in glucosteroids, my blood vessels are full of adrenaline, and if it weren't for my endogenous opiates I'd have driven the car into a tree on the way home. My dopamine levels need lifting. Pour me a Chardonnay, and I'll be down in a minute" (as quoted by MacFarquhar, 2007, p. 69),

It's funny, until you stop to reflect on the fact that these people are serious, and that their students have taken to talking like this too.⁷ 

But really, when you step back, you realize that this is just an exercise in translation, not much different in principle from rendering English into French -- except it's not as effective. You'd have no idea what Pat was talking about if you didn't already know something about the correlation between serotonin and depression, between adrenaline and arousal, between endogenous opiates and pain relief, and between dopamine and reward. But is it really her serotonin levels that are low, or is it her norepinephrine levels -- and if it's serotonin, how does she know? Only by translating her feelings of depression into a language of presumed biochemical causation -- a language that is understood only by those, like Paul, who already have the secret decoder ring. And even then, the translation isn't very reliable. We know about adrenalin and arousal, but is Pat preparing for fight-or-flight (Cannon, 1932), or tend-and-befriend (S. E. Taylor, 2006)?  Is she getting pain relief or positive pleasure from those endogenous opiates? And after going through the first five screens of a Google search, I still couldn't figure out whether Pat's glucosteroids were generating muscle activity, reducing bone inflammation, or increasing the pressure in her eyeballs. 

And note that even Pat and Paul can't carry it off. What's all this about "talk" and "Chardonnay"? I suppose that what she really means to say is:

Your Broca's area should be soaking in inhibitory neurotransmitters for a while, so that my mirror neurons don't automatically emulate your articulatory gestures as you push air into your larynx, across your vocal cords, and into your mouth and nose (A.M. Liberman, Cooper, Shankweiler, & Studdert-Kennedy, 1967; A. M. Liberman & Mattingly, 1985)

and

Mix me a 12-13% solution of alcohol in water, along with some glycerol and a little reducing sugar, plus some tartaric, acetic, malic, and lactic acids, with a pH level of about 3.25 (Orlic, Redzepovic, Jeromel, Herjavec, & Iacumin, 2007; Schreier, 1979).

What's missing here is any sense of meaning -- and, specifically, of the meaning of this social interaction. Why doesn't Pat pour her own drink? Why Chardonnay instead of Sauvignon Blanc -- or, for that matter, Two-Buck Chuck? For all her brain cares, she might just as well mainline ethanol in a bag of saline solution. And, for that matter, why is Pat talking to Paul at all? Why doesn't she just give him an injection of oxytocin?  But no: What she really wants is for her husband to care enough about her to fix her a drink -- not an East Coast martini but a varietal wine that almost defines California living -- and give her some space -- another stereotypically Californian request -- to wind down. That's what the social interaction is all about; and this is entirely missing from the eliminative materialist reduction. 

The problem is that you can't reduce the mental and the social to the neural without leaving something crucial out -- namely, the mental and the social. And when you leave out the mental and the social, you've just kissed psychology (and the rest of the social sciences) good-bye. That is because psychology isn't just positioned between the biological sciences and the social sciences. Psychology is both a biological science and a social science. That is part of its beauty and it is part of its tension. Comte recognized this, even before psychology as we know it today was born -- and he liked phrenology, too, because of its emphasis on affective and social functions (Allport, 1954). 

All sciences want to provide objective explanations of the real world, but they differ in the kind of reality they're trying to explain, and the kind of knowledge they generate (J. R. Searle, 1992, 1995) (see also Zerubavel, 1997). We usually think that there are only two modes of existence and two modes of knowledge: objective existence, and objective truth that is simply a matter of brute fact, and subjective existence, and subjective truth which depends on the attitude or point of view of some observer. But as Searle has pointed out, there is no isomorphism between ontological and epistemological objectivity and subjectivity. That is, there are some things in the world that have an objective existence because they are intrinsic to nature, there are other things that exist objectively, even though they have been brought into existence by the mental processes of observers: they are the product of individual or collective intentionality.⁸ It is an objective fact that my cat Guinevere is a cat: it's intrinsic to her DNA. But it's also an objective fact that Guinivere is my pet, even though this fact is true only because I construe her that way. Similarly, to use two of Searle's examples, money is money and marriage is marriage only because some organization or institution says they are; but these features of institutional reality nonetheless have an ontologically objective mode of existence. 

The natural sciences try to understand those intrinsic features of the world that exist independently of the observer. Neuroscience is like this: the brain exists, and the principles of neural depolarization and synaptic transmission are what they are, regardless of our beliefs and attitudes about them. And that's also true to some extent of psychology. We can say that the psychophysical laws, the principle of association by contingency, homeostatic regulation, the relation between depth of processing and recall, the structure of concepts as fuzzy sets (or whatever), and the availability heuristic for making judgments of frequency are all observer-independent facts about how the mind works. They're true for everybody, everywhere, throughout all time. That's one reason, I think, why cognitive psychologists tend to select their stimulus materials arbitrarily. If you're doing a standard verbal-learning experiment, for example, so long as you control for things like word-length and imagery value, it doesn't much matter which words you ask your subjects to memorize. But that's not all there is to psychology. Bartlett (1932) famously criticized the natural-science approach to mental life, as practiced by Fechner and Ebbinghaus, precisely because it ignored the person's "effort after meaning". 

Somewhere Paul Rozin has pointed out that psychology has been more interested in how people eat than in what people eat -- and that that's too bad (an example of the general argument can be found in Rozin, 1996). People don't want just to eat, in order to correct their blood sugar levels. Rather, people want to eat particular things, because they like them, or because eating them in certain contexts has a certain meaning for them. And they avoid eating other, perfectly good foods, either because they don't like them or because they're obeying institutional rules telling them what is permitted and what is forbidden. Not to press the point too much, but I'd suggest that psychology as a natural, biological science is interested in the how of mind and behavior, while psychology as a social science is interested in the what of mind and behavior -- what people actually think, and feel, and want (and do). That's especially true of social psychology, which is why just about the first thing that social psychologists did was to figure out how to construct attitude scales (Thurstone, 1931). 

The natural sciences try to understand those features of the world that are observer-independent, existing without regard to the beliefs, feelings, and desires of the observer -- in other words, a world in which there are no conscious agents, where mental activity has no effect on the way things are. But the social sciences seek to understand those aspects of reality that are observer-dependent -- because they are created either through the intentional processes of an individual or through the collective intentionality of some group, organization, or institution. Just as psychology as a social science tries to understand behavior in terms of the individual's subjective construction of reality, so the rest of the social sciences try to understand behavior in terms of social and institutional reality. This is the difference between the natural and the social sciences -- and it's a difference that is qualitative in nature. You can't make a natural science out of a social science without losing the subject matter of social science. 

When, in the movie Sideways (2004), Jack talks about drinking Merlot, that may result from the operation of some politeness module in the brain. But when Miles says "I am not drinking any... Merlot!", that has nothing to do with nutritional value, carbohydrate content, or even alcohol levels -- all the things that a natural science of oenology considers important. But it has a great deal to do with the meaning of Merlot for Miles, his identity as a oenophile, and his view of the kinds of people who like Merlot -- just the sorts of things that would interest a social scientist of wine.

To be sure, social reality is the product of individual minds (working together), and personal reality is the product of individual minds (working alone), and individual minds are the product of individual brains. But a science that ignores the subjectively real in favor of the objectively real, and that ignores observer-dependent facts in favor of observer-independent facts, leaves out the very things that make social science -- social science. So with our best theories and experimental methods in hand, and the biggest magnets money can buy, let's proceed to identify the neural systems involved in social behavior. It's a great project, and there are wonderful things to be learned. But let's not forget what the social sciences are all about: Let's not get lost in the soups and the sparks. 

Footnotes

¹As a start, Higgins and Kruglanski (2000) have announced an interdisciplinary "motivational science", apparently modeled on cognitive science; "motivational neuroscience" cannot be far behind.  Return to text.

²I suspect that the proper relationship between psychology and neuroscience is a little like the situation in physics.  It may well be the case that string theory will produce the final Theory of Everything that unites the strong and weak forces with electromagnetism and gravity, and time with space, and complete the agenda of theoretical physics.  On the other hand, whether strings vibrate in 26 dimensions or only 10 makes no difference to Newton 's falling apple, or the laws of planetary motion, or the expanding universe.  Momentum will still equal mass times velocity, and E = mc².  Return to text.

³My title refers to a line in "A Psalm of Life", by Henry Wadsworth Longfellow, which describes the impact that great men and women make on history -- maybe Goethe (Longfellow first recited the poem, prior to its publication, at the conclusion of a lecture on the poet); maybe Washington (at the time, Longfellow was living in the same house in Cambridge -- indeed, the very same rooms -- that Washington occupied when he took command of the Colonial Army during the Revolutionary War).  But his point applies to all of us, not just the great: we can all leave our footprints on the sands of time.  Phineas Gage was not a great man in the sense that Goethe and Washington were, but he has left his mark on history, as the issues raised by his case continue to concern us today -- especially as we consider how to pursue this new discipline of social neuroscience.  Return to text.

⁴As Macmillan (Malcolm Macmillan, 2000; M. Macmillan, 2000; Macmillan, 1986) argues, it is important not to exaggerate Gage's post-morbid difficulties.  He did return to work, in the livery and coach business if not on the railroad, including nearly seven years in Chile before ending up in San Francisco -- where at least he died of epilepsy and not in a barfight on the Barbary Coast !  It seems that a lot of what many authorities know of the Gage case is actually an imaginative reconstruction based on what is now known about the frontal lobes.  But all we really know about Gage himself is what we know from Harlow 's first-hand account.  And because Harlow himself was a closeted phrenologist, acquainted with Sizer for years before either of them ever laid eyes on Gage, even Harlow 's accounts may be to an unknown degree an imaginative construction. Return to text.

⁵In our early presentations of social-cognitive neuropsychology, Stan Klein and I unaccountably failed to cite Jackendoff's work.  Jackendoff himself was too polite to ever mention it, but I take this opportunity to correct the record. Return to text.

⁶With apologies to Rae Carlson (1984).  Return to text.

⁷Eliminative reductionism is not simply a project of some philosophical iconoclasts.  The tendency toward eliminativism can be detected in Goleman's assertion that neuroscientific findings enhance the ontological status of social intelligence, and in the idea, proposed by some advocates of neurolaw, that the legal concept of personal responsibility is obviated by the "finding" that behavior is caused by the brain.  Return to text.

⁸And just to complicate things further, there are things that have a subjective mode of existence but nonetheless are observer-independent.  To use Searle's example: if I'm in pain, it's true that I'm in pain regardless of what anyone else may think about it.   Return to text.