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Foundations of Cognitive Psychology

813 Pages · 2006 · 12.88 MB · English

  • Foundations of Cognitive Psychology

    Preface


    Daniel J. Levitin


    What Is Cognition?


    Cognition encompasses the scientific study of the human mind and how it


    processes information; it focuses on one of the most difficult of all mysteries


    that humans have addressed. The mind is an enormously complex system


    holding a unique position in science: by necessity, we must use the mind to


    study itself, and so the focus of study and the instrument used for study are


    recursively linked. The sheer tenacity of human curiosity has in our own life-


    times brought answers to many of the most challenging scientific questions we


    havehadtheambitiontoask.Althoughmanymysteriesremain,atthedawnof


    the twenty-first century, we find that we do understand much about the fun-


    damental laws of chemistry, biology, and physics; the structure of space-time,


    the origins of the universe. We have plausible theories about the origins and


    nature of life and have mapped the entire human genome. We can now turn


    our attention inward, to exploring the nature of thought, and how our mental


    life comes to be what it is.


    Therearescientistsfromnearlyeveryfieldengagedinthispursuit.Physicists


    try to understand how physical matter can give rise to that ineffable state we


    call consciousness, and the decidedly nonphysical ‘‘mind stuff’’ that Descartes


    and other philosophers have argued about for centuries. Chemists, biologists,


    and neuroscientists join them in trying to explicate the mechanisms by which


    neuronscommunicatewitheachotherandeventuallyformourthoughts,mem-


    ories,emotions,anddesires.Attheotherendofthespectrum,economistsstudy


    how we balance choices about limited natural and financial resources, and


    anthropologists study the influence of culture on thought and the formation of


    societies. So at one end we find scientists studying atoms and cells, at the other


    end there are scientists studying entire groups of people. Cognitive psycholo-


    gists tend to study the individual, and mental systems within individual brains,


    although ideally we try to stay informed of what our colleagues are doing. So


    cognitionisatruly interdisciplinary endeavor,andthiscollectionofreadingsis


    intended to reflect that.


    Why Not a Textbook?


    This book grew out of a course I took at the Massachusetts Institute of Tech-


    nology (MIT) in 1975, from Susan Carey and Merrill Garrett (with occasional


    guest lectures by Mary Potter), and courses I taught at the University of Ore- xiv Preface


    gon, Stanford University, and the University of California at Berkeley. When I


    took cognition at MIT, there were only two textbooks about cognition asa field


    (if it could even be thought of as a field then): Ulric Neisser’s Cognitive Psy-


    chology and Michael Posner’s Cognition: An Introduction. Professors Carey and


    Garrett supplemented these texts with a thick book of hand-picked readings


    from Scientific American and mainstream psychology journals. Reading journal


    articles prepared the students for the debates that characterize science. Susan


    andMerrillskillfullybroughtthesedebatesoutintheclassroom,throughinter-


    active lectures and the Socratic method. Cognition is full of opposing theories


    and controversies. It is an empirical science, but in many cases the same data


    are used to support different arguments, and the reader must draw his or her


    own conclusions. The field of cognition is alive, dynamic, and rediscovering


    itself all the time. We should expect nothing less of the science devoted to


    understanding the mind.


    Today there are many excellent textbooks and readers devoted to cognition.


    Textbooks are valuable because they select and organize a daunting amount of


    information and cover the essential points of a topic. The disadvantage is that


    they do not reflect how psychologists learn about new research—this is most


    often done through journal articles or ‘‘high-level’’ book chapters directed to


    the working researcher. More technical in nature, these sources typically reveal


    details of an experiment’s design, the measures used, and how the findings are


    interpreted. They also reveal some of the inherent ambiguity in research (often


    hidden in a textbook’s tidy summary). Frequently students, when confronted


    with the actual data of a study, find alternate interpretations of the findings,


    and come to discover firsthand that researchers are often forced to draw their


    own conclusions. By the time undergraduates take a course in cognition (usu-


    ally their second or third course in psychology) they find themselves wonder-


    ing if they ought to major in psychology, and a few even think about going to


    graduateschool.Ibelievetheyoughttoknowmoreaboutwhatitisliketoread


    actual psychology articles, so they’ll know what they’re getting into.


    On theotherhand, abookof readingscomposedexclusively ofsuchprimary


    sources would bedifficult toread without a suitablegrounding in thefieldand


    wouldleaveoutmanyimportantconcepts,lackinganoverview.Thatis,itmight


    tend to emphasize the trees at the expense of the forest.


    Therefore, the goal of this anthology is to combine the best of both kinds


    of readings. By compiling an anthology such as this, I was able to pick and


    choose my favorite articles, by experts on each topic. Of the thirty-nine selec-


    tions, ten are from undergraduate textbooks, six are from professional journals,


    sixteen are chapters from ‘‘high-level’’ books aimed at advanced students and


    research scientists, and seven are more or less hybrids, coming from sources


    writtenfortheeducatedlayperson,suchasScientificAmericanorpopularbooks


    (e.g.,Gardner,Norman).Thisbookisnotintendedtobeacollectionofthemost


    important papers in the history of cognitive psychology; other authors have


    done this extremely well, especially LloydKomatsuinhisexcellentExperiment-


    ingwith the Mind (1994, Brooks/Cole). It is intended as a collection of readings


    that can serve as the principal text for a course in cognitive psychology or cog-


    nitive science. Preface xv


    TheparticularreadingsincludedhereowetheirevolutiontoacourseItaught


    at the University of California at Berkeley in the fall of 1999, ‘‘Fundamental


    Issues in Cognitive Science.’’ The readings for that course had been carefully


    honed over ten years by Stephen Palmer and Alison Gopnik, outstanding


    teacherswhosecoursesaremotivatedbyanunderstandingofthephilosophical


    basis for contemporary cognitive psychology. I had never seen cognitive psy-


    chologytaughtthisway,butonceIdidIcouldn’timagineteachingitanyother


    way.AfundamentalassumptionIsharewiththemisthatcognitivepsychology


    is in many respects empirical philosophy. By that I mean that the core questions


    in cognitive psychology were for centuries considered the domain of philoso-


    phers. Some of these questions include: What is the nature of thought? Does


    languageinfluencethought? Are memoriesand perceptionsaccurate?Howcan


    we ever know if other people are conscious?


    Aristotlewasthefirstinformation-processingtheorist,andwithoutexaggera-


    tion one can argue that modern cognitive psychology owes him its heritage.


    Descartes launched modern approaches to these questions, and much current


    debate references his work. But for Aristotle, Descartes, Hume, Locke, Husserl,


    and others, the questions remained in the realm of philosophy. A century and


    a half ago this all changed when Wundt, Fechner, Helmholtz, and their cohorts


    established the first laboratories in which they employed empirical methods to


    probewhathadpreviouslybeenimpenetrabletotruescience:themind.Philos-


    ophers framed the questions, and mental scientists (as they were then some-


    times called) conducted experiments to answer them.


    Today, the empirical work that interests me most in the field of Cognition is


    theory-drivenandbuildsonthesephilosophicalfoundations.Andanewgroup


    of philosophers, philosophers of mind, closely monitor the progress made by


    cognitive psychologists in order to interpret and debate their findings and to


    place them in a larger context.


    Who Is This For?


    The book you have before you is intended to be used as a text for the under-


    graduate cognitive psychology class I teach at McGill University. I hope that


    others will find some value in it as well. It should also be suitable for students


    who wish to acquaint themselves through self-study with important ideas in


    cognition. The ambitious student or professor may want to use this to sup-


    plement a regular textbook as a way to add other perspectives on the topics


    covered. It may also be of use to researchers as a resource that gathers up key


    articles in one place. It presupposes a solid background in introductory psy-


    chologyandresearchmethods.Studentsshouldhaveencounteredmostofthese


    topics previously, and this book gives them an opportunity to explore them


    more deeply.


    How the Book Is Organized and How It Differs from Other Books


    The articles in this reader are organized thematically around topics tradition-


    ally found in a course on cognitive psychology or cognitive science at the uni- xvi Preface


    versitylevel.Theorderofthereadingscouldcertainlybevariedwithoutlossof


    coherence, although I think that the first few readings fit better at the begin-


    ning. After that any order should work.


    The readings begin with philosophical foundations, and it is useful to keep


    thesein mind when reading the remainder of the articles. This reflectsthe view


    that good science builds on earlier foundations, even if it ultimately rejects


    them.


    This anthology differs from most other cognition readers in its coverage of


    several topics not typically taught in cognition courses. One is human factors


    and ergonomics, the study of how we interact with tools, machines, and arti-


    facts, and what cognitive psychology can tell us about how to improve the de-


    sign of such objects (including computers); this is represented in the excellent


    papers by Don Norman. Another traditionally underrepresented topic, evolu-


    tionary psychology, is represented here by two articles, one by David Buss and


    his colleagues, and the other by John Tooby and Leda Cosmides. Also unusual


    are the inclusion of sections on music cognition, experimental design, and as


    mentioned before, philosophical foundations. You will find that there is some-


    what less coverage of neuroscience and computer science perspectives on cog-


    nition, simply because in our department at McGill, we teach separate courses


    on those topics, and this reader reflects an attempt to reduce overlap.


    Acknowledgments


    Iwouldliketothankthemanypublishersandauthorswhoagreedtolettheirworksbeincluded


    here, my students, and Amy Brand, Tom Stone, Carolyn Anderson, Margy Avery, and Kathleen


    CarusoatMITPress.Iamindebtedinparticulartothefollowingstudentsfrommycognitionclass


    for their tireless efforts at proofreading and indexing this book: Lindsay Ball, Ioana Dalca, Nora


    Hussein, Christine Kwong, Aliza Miller, Bianca Mugyenyi, Patrick Sabourin, and Hannah Wein-


    stangel.Ialsowouldliketothankmywife,CarolineTraube,whoisaconstantsourceofsurprise


    and inspiration and whose intuitions about cognitive psychology have led to many new studies.


    Finally, I was extraordinarily lucky to have three outstanding scholars as teachers: Mike Posner,


    DougHintzman,andRogerShepard,towhomthisbookisdedicated.Iwouldliketothankthem


    fortheirpatience,inspiration,support,andfriendship. part i


    Foundations—Philosophical Basis, The Mind/Body


    Problem Chapter 1


    Visual Awareness


    Stephen E. Palmer


    1.1 Philosophical Foundations


    The first work on virtually all scientific problems was done by philosophers,


    and the nature of human consciousness is no exception. The issues they raised


    have framed the discussion for modern theories of awareness. Philosophical


    treatments of consciousness have primarily concerned two issues that we will


    discuss before considering empirical facts and theoretical proposals: The mind-


    body problem concerns the relation between mental events and physical events


    inthebrain,andtheproblemofothermindsconcernshowpeoplecometobelieve


    that other people (or animals) are also conscious.


    1.1.1 The Mind-Body Problem


    Althoughthereisalonghistorytohowphilosophershaveviewedthenatureof


    the mind (sometimes equated with the soul), the single most important issue


    concernswhathascometobecalledthe mind-body problem:What istherelation


    between mental events (e.g., perceptions, pains, hopes, desires, beliefs) and


    physical events (e.g., brain activity)? The idea that there is a mind-body prob-


    lem to begin with presupposes one of the most important philosophical posi-


    tions about the nature of mind. It is known as dualism because it proposes that


    mind and body are two different kinds of entities. After all, if there were no


    fundamental differences between mental and physical events, there would be


    no problem in saying how they relate to each other.


    Dualism The historical roots of dualism are closely associated with the writ-


    ings of the great French philosopher, mathematician, and scientist Rene´


    Descartes. Indeed, the classical version of dualism, substance dualism, in which


    mind and body are conceived as two different substances, is often called Carte-


    sian dualism. Because most philosophers find the notion of physical substances


    unproblematic, the central issue in philosophical debates over substance dual-


    ism is whether mental substances exist and, if so, what their nature might be.


    Vivid sensory experiences, such as the appearance of redness or the feeling of


    pain,areamongtheclearestexamples,butsubstancedualistsalsoincludemore


    abstract mental states and events such as hopes, desires, and beliefs.


    The hypothesized mental substances are proposed to differ from physical


    ones in their fundamental properties. For example, all ordinary physical matter


    Fromchapter13inVisionScience:PhotonstoPhenomenology(Cambridge,MA:MITPress,1999),618–


    630.Reprintedwithpermission. 4 StephenE.Palmer


    has a well-defined position, occupies a particular volume, has a definite shape,


    and has a specific mass. Conscious experiences, such as perceptions, remem-


    brances, beliefs, hopes, and desires, do not appear to have readily identifiable


    positions, volumes, shapes, and masses. In the case of vision, however, one


    might object that visual experiences do have physical locations and extensions.


    Thereisan important sensein which my perception of a redball on thetableis


    locatedonthetablewheretheballisandisextendedoverthesphericalvolume


    occupied by the ball. What could be more obvious? But a substance dualist


    would counter that these are properties of the physical object that I perceive


    rather than properties of my perceptual experience itself. The experience is in


    my mind rather than out there in the physical environment, and the location,


    extension, and mass of these mental entities are difficult to define—unless one


    makes the problematic move of simply identifying them with the location, ex-


    tension, and mass of my brain. Substance dualists reject this possibility, believ-


    ing instead that mental states, such as perceptions, beliefs, and desires, are


    simply undefined with respect to position, extension, and mass. In this case,


    it makes sense to distinguish mental substances from physical ones on the


    grounds that they have fundamentally different properties.


    We can also look at the issue of fundamental properties the other way


    around: Do experienceshaveanypropertiesthat ordinary physicalmatterdoes


    not?Twopossibilitiesmeritconsideration.Oneisthatexperiencesaresubjective


    phenomena in the sense that they cannot be observed by anyone but the person


    having them. Ordinary matter and events, in contrast, are objective phenomena


    because they can be observed by anyone, at least in principle. The other is that


    experiences have what philosophers call intentionality: They inherently refer to


    things other than themselves.1 Your experience of a book in front of you right


    now is about the book in the external world even though it arises from activity


    in your brain. This directedness of visual experiences is the source of the confu-


    sion we mentioned in the previous paragraph about whether your perceptions


    have location, extension, and so forth. The physical objects to which such per-


    ceptual experiences refer have these physical properties, but the experiences


    themselves do not. Intentionality does not seem to be a property that is shared


    by ordinary matter, and if this is true, it provides further evidence that con-


    scious experience is fundamentally different.


    It is possible to maintain a dualistic position and yet deny the existence of


    any separate mental substances, however. One can instead postulate that the


    brainhascertainuniquepropertiesthatconstituteitsmentalphenomena.These


    properties are just the sorts of experiences we have as we go about our every-


    day lives, including perceptions, pains, desires, and thoughts. This philosophi-


    cal position on the mind-body problems is called property dualism. It is a form


    of dualism because these properties are taken to be nonphysical in the sense of


    not being reducible to any standard physical properties. It is as though the


    physical brain contains some strange nonphysical features or dimensions that


    are qualitatively distinct from all physical features or dimensions.


    These mental features or dimensions are usually claimed to be emergent prop-


    erties: attributes that simply do not arise in ordinary matter unless it reaches a


    certain level or type of complexity. This complexity is certainly achieved in the


    human brain and may also be achieved in the brains of certain other animals. VisualAwareness 5


    The situation is perhaps best understood by analogy to the emergent property


    of being alive. Ordinary matter manifests this property only when it is orga-


    nized in such a way that it is able to replicate itself and carry on the required


    biological processes. The difference, of course, is that being alive is a property


    that we can now explain in terms of purely physical processes. Property dual-


    ists believe that this will never be the case for mental properties.


    Even if one accepts a dualistic position that the mental and physical are


    somehow qualitatively distinct, there are several different relations they might


    have to one another. These differences form the basis for several varieties of


    dualism. One critical issue is the direction of causation: Does it run from mind


    to brain, from brain to mind, or both? Descartes’s position was that both sorts


    of causation are in effect: events in the brain can affect mental events, and


    mental events can also affect events in the brain. This position is often called


    interactionismbecauseitclaimsthatthementalandphysicalworldscaninteract


    causally with each other in both directions. It seems sensible enough at an in-


    tuitive level. No self-respecting dualist doubts the overwhelming evidence that


    physical events in the brain cause the mental events of conscious experience.


    The pain that you feel in your toe, for example, is actually caused by the firing


    of neurons in your brain. Convincing evidence of this is provided by so-called


    phantomlimbpain,inwhichamputeesfeelpain—sometimesexcruciatingpain—


    in their missing limbs (Chronholm, 1951; Ramachandran, 1996).


    In the other direction, the evidence that mental events can cause physical


    ones is decidedly more impressionistic but intuitively satisfying to most inter-


    actionists. They point to the fact that certain mental events, such as my having


    the intention of raising my arm, appear to cause corresponding physical


    events, such as the raising of my arm—provided I am not paralyzed and my


    arm is not restrained in any way. The nature of this causation is scientifically


    problematic, however, because all currently known forms of causation concern


    physicaleventscausingotherphysicalevents.Evenso,otherformsofcausation


    that have not yet been identified may nevertheless exist.


    Not all dualists are interactionists, however. An important alternative ver-


    sionofdualism,calledepiphenomenalism,recognizesmentalentitiesasbeingdif-


    ferent in kind from physical ones yet denies that mental states play any causal


    roleintheunfoldingofphysicalevents.Anepiphenomenalistwouldarguethat


    mental states, such as perceptions, intentions, beliefs, hopes, and desires, are


    merely ineffectual side effects of the underlying causal neural events that take


    place in our brains. To get a clearer idea of what this might mean, consider the


    following analogy: Imagine that neurons glow slightly as they fire in a brain


    and that this glowing is somehow akin to conscious experiences. The pattern


    of glowing in and around the brain (i.e., the conscious experience) is clearly


    caused by the firing of neurons in the brain. Nobody would question that. But


    the neural glow would be causally ineffectual in the sense that it would not


    cause neurons to fire any differently than they would if they did not glow.


    Therefore, causation runs in only one direction, from physical to mental, in an


    epiphenomenalist account of the mind-body problem. Although this position


    denies any causal efficacy to mental events, it is still a form of dualism because


    it accepts the existence of the ‘‘glow’’ of consciousness and maintains that it is


    qualitatively distinct from the neural firings themselves. 6 StephenE.Palmer


    Idealism Not all philosophical positions on the mind-body problem are dual-


    istic. The opposing view is monism: the idea that there is really just one sort


    of stuff after all. Not surprisingly, there are two sorts of monist positions—


    idealism and materialism—one for each kind of stuff there might be. A monist


    who believestheretobenophysicalworld,butonlymentalevents,iscalledan


    idealist (from the ‘‘ideas’’ that populate the mental world). This has not been a


    very popular position in the history of philosophy, having been championed


    mainly by the British philosopher Bishop Berkeley.


    Themost significant problem for idealism is how to explain the commonality


    of different people’s perceptions of the same physical events. If a fire engine


    races down the street with siren blaring and red lights flashing, everyone looks


    toward it, and they all see and hear pretty much the same physical events, al-


    beit from different vantage points. How is this possible if there is no physical


    world that is responsible for their simultaneous perceptions of the sound and


    sight of the fire engine? One would have to propose some way in which the


    minds of the various witnesses happen to be hallucinating exactly correspond-


    ing eventsatexactlycorrespondingtimes.Berkeley’sanswer wasthatGodwas


    responsibleforthisgrandcoordination,butsuchclaimshaveheldlittleswayin


    modern scientific circles. Without a cogent scientific explanation of the com-


    monality of shared experiences of the physical world, idealism has largely be-


    come an historical curiosity with no significant modern following.


    Materialism The vast majority of monists believe that only physical entities


    exist. They are called materialists. In contrast to idealism, materialism is a very


    common view among modern philosophers and scientists. There are actually


    two distinct forms of materialism, which depend on what their adherents


    believe the ultimate status of mental entities will be once their true physical


    nature is discovered. One form, called reductive materialism, posits that mental


    eventswillultimatelybereducedtomaterialeventsinmuchthesamewaythat


    other successful reductions have occurred in science (e.g., Armstrong, 1968).


    Thisviewisalsocalledmind-brainidentitytheorybecauseitassumesthatmental


    events are actually equivalent to brain events and can be talked about more or


    less interchangeably, albeit with different levels of precision.


    A good scientific example of what reductive materialists believe will occur


    when the mental is reduced to the physical is the reduction in physics of ther-


    modynamic concepts concerning heat to statistical mechanics. The temperature


    of a gas in classical thermodynamics has been shown to be equivalent to the


    average kinetic energy of its molecules in statistical mechanics, thus replacing


    the qualitatively distinct thermodynamic concept ofheat withthe moregeneral


    and basic concept of molecular motion. The concept of heat did not then dis-


    appear from scientific vocabulary: it remains a valid concept within many


    contexts. Rather, it was merely given a more accurate definition in terms of


    molecular motion at a more microscopic level of analysis. According to reduc-


    tive materialists, then, mental concepts will ultimately be redefined in terms


    of brain states and events, but their equivalence will allow mental concepts


    to remain valid and scientifically useful even after their brain correlates are


    discovered. For example, it will still be valid to say, ‘‘John is hungry,’’ rather


    than, ‘‘Such-and-such pattern of neural firing is occurring in John’s lateral


    hypothalamus.’’


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