Amanda L. Woodward

Dept of Psychology, University of Chicago,5848 South University Avenue, Chicago,IL 60637, USA.e-mail: woodward@uchicago.edu

References

1 Heyes, C. (2001) Causes and consequences ofimitation. Trends Cogn. Sci. 5, 253–361

2 Tomasello, M. et al. (1993) Cultural learning.Behav. Brain Sci. 16, 495–552

3 Gergely, G. et al. (2002) Developmentalpsychology: rational imitation in preverbalinfants. Nature, 415, 755

Opposing

associationism

The Symbolic Foundations of

Conditioned Behavior

by C. Randy Gallistel and John Gibbon,Lawrence Erlbaum, 2002. £49.95 (196 pages) ISBN 0 8058 2934 2

This is an important, provocative andpolemical book. The target of the polemicis associationism, the most venerabletradition in learning stretching back tothe British empiricist philosophers, Lockeand Hume. Not only do Randy Gallisteland the late, and greatly missed,John Gibbon attack associationism in itscitadel – namely animal conditioning –but they also seek to usurp its authoritywith a synthesis of two cognitive theories.The first is Scalar Expectancy Theory(SET), developed by Gibbon over manyyears to explain the temporal control of behaviour, and the second is RateEstimation Theory (RET) that waselaborated by Gallistel over 10 years agoto account for the acquisition ofconditioning. This synthesis waspresented in a paper published inPsychological Review in 2000, and thepresent volume is an elaboration of that paper.

Gallistel and Gibbon challengeassociationism on three main issues. The first concerns the representationalpoverty of the concept of associativestrength. According to associative theory,the predictive relationship between aconditioned stimulus (CS) and reinforceris encoded by the strength of anassociation, a form of encoding thatconflates many different features of therelationship, most notably the amount of training with the probability and

magnitude of reinforcement. The secondissue is the timescale invariance ofacquisition which the authors claim isboth the single most important discoveryabout conditioning, and problematic forassociative theory. This invariance refersto the fact that acquisition is determinedby the ratio of the interval betweenreinforced CSs to the duration of the CS,whatever the absolute lengths of theseintervals and the probability ofreinforcement. The final issue concernsthe failure of associative theory to providean account of the subtle timing ofconditioned behaviour.

In response to these challenges,Gallistel and Gibbon offer a cognitivetheory in which they assume that, during training, an animal encodes andremembers both the times at whichreinforcers occur in the CS (based onSET) and the rates of their occurrence(based on RET). Then, when presentedwith a test CS, the animal retrievesmemories of these intervals and ratesbefore choosing whether to respond and,if so, when to respond, on the basis ofdecision rules. This account is applied not only to response acquisition andtiming but also to complex temporalinferences revealed in studies ofsecondary conditioning, and to theoperant choice behaviour.

Whether or not this cognitive theorypresents a serious challenge to thehegemony of associationism is far fromcertain. Gallistel and Gibbon clearly seekto influence the neuroscience communityby persuading us of the illusory nature of what they call the ‘neurobiologicaltransparency’ of associationism. But bewarned – this is not an introductory bookand a critical appreciation of its centraltheses requires a firm grounding in bothconditioning and associative learningtheory. Moreover, I suspect thatassociative theorists will be mildlyirritated by the numerous, dismissiveover-generalizations that ignore many ofthe subtleties of their theories. My ownjudgment is that RET is too baroque anaccount to have a sustained influence in the field. Even so, it must beacknowledged that this book is a uniquecontribution to conditioning andlearning. To maintain a healthy andgenerative state, every theoreticalprogramme needs an official oppositionand, at long last, associationism hasfound a worthy one.

Anthony Dickinson

Dept of Experimental Psychology,University of Cambridge, Downing Street,Cambridge, UK CB2 3EB.e-mail: ad15@cus.cam.ac.uk

Back to nature

The Blank Slate: The Modern Denial of

Human Nature

by Steven Pinker, Viking 2002. £25.00/$27.95 (509 pages) ISBN 0 670 03151 8

When StevenPinker’s LanguageInstinct came out in 1994, aphilosopher friendof mine described it as a wonderfulbook with an awfulending. Beinggreatly influencedby Noam Chomsky,she was

sympathetic to Pinker’s arguments thatlanguage is an innate module – aninstinct – and persuaded as well thatlanguage has evolved through naturalselection. But she was troubled by hissuggestion in the final chapter that thesame approach should be extended topsychology more generally. Pinker’s nextbook, How the Mind Works, did just that,applying a biological perspective toeverything from depth perception tomaternal love to aesthetic appreciation.She hated this book, seeing the wholeenterprise of evolutionary psychology as repugnant: morally suspect andpolitically reactionary.

The Blank Slate is written for her.Pinker does a lot of things in thisextraordinary work, but his main goal is to show that the notion of an evolvedhuman nature does not have the negativeconnotations that many people think itdoes. There is no conflict between amaterialist and biological perspective onthe mind and the religious, political andmoral values that people hold most dear.

Pinker starts by identifying threedoctrines: the blank slate (mentalstructure comes from the environment,mostly from culture), the noble savage(humans are essentially good) and theghost in the machine (mental life is the

TRENDS in Cognitive Sciences Vol.6 No.12 December 2002

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product of an immaterial soul). Pinkerargues that these views are pervasive,quoting adherents ranging fromMao Zedong to Walt Disney, and underliecontemporary discussion of just about anytopic that matters. He also reviews theugly history of how those who reject thesedoctrines (even in very mild ways, such as tentatively suggesting that aggressionhas biological roots) become the targets of ad hominem attacks, bizarremischaracterizations, censorship, andeven physical assault. The doctrines aresometimes presented in extreme formsthat even their adherents do not believe,something that Pinker describes as a sure sign of a cult-like mentality, where‘fantastical beliefs are flaunted as proof ofone’s piety’. Although the tone is calm andreasoned throughout, Pinker plainly takesdelight in quoting, and dismantling, some of these sillier claims.

Of course, if it were true that rejectionof these doctrines entails an endorsementof sexism, racism, infanticide, war, rape,and everything else that is evil in theworld, then a little bit of censorship andhypocrisy might well be justified. In thecore of this book, Pinker identifies severalanxieties that people have about anevolved biological human nature – suchthat it would justify discrimination, orwould strip life of any higher meaning –and argues that these are unfounded.

He then goes further and reviews five ‘hot buttons’– politics, violence, gender,children, and the arts. For each, heproposes that an enhanced appreciation of human nature can allow us to betterunderstand, and improve, those areasthat are most central to our lives.

This is a brilliant book. It isbeautifully written, and addressesprofound issues with courage and clarity.There is nothing else like it, and it isgoing to have an impact that extends wellbeyond the scientific academy. There isalso plenty to disagree with. For onething, while Pinker makes an excellentcase that a scientific conception of humannature does not clash with liberalWestern values, he is too optimistic whenit comes to reconciliation with religion.Someone who is devout can easily give upon the blank slate and the noble savage –but the ghost in the machine is a verydifferent story. Pinker notes that ‘somebiologists argue that a sophisticateddeism, towards which many religions areevolving, can be made compatible with an evolutionary understanding of themind and human nature’. But such asophisticated deism would be so toothlessand secularized that it barely deserves tobe called a religion. The sorts of religionsthat people actually believe in includebeliefs such as the soul surviving thedeath of the body and ascending to

heaven. If you accept the scientific viewof human nature, you have to give thisup. This is not small potatoes.

Pinker might be too optimistic as wellabout the relevance of scientific theoriesto social and political life. He is plainlyright that our feelings about issues suchas good parenting, violent crime andabortion are deeply related to tacitassumptions about human nature, and he makes a persuasive case that this isalso true for broader-scale ideologies suchas capitalism and communism. Butalthough it is flattering to think thatthese tacit theories come from thediscoveries of those who study mental life, this might just be hubris. Theassumptions about human nature held bydictators, reformers, racists, utopians andeveryone else might have other origins,and it is unclear how much they areaffected by insights from the laboratory or the seminar room. Pinker approvinglyquotes Chekhov, who wrote ‘Man willbecome better when you show him whathe is like’. It would be nice if this weretrue, but so far there is little evidence to support it.

Paul Bloom

Dept of Psychology, Yale University, PO Box 208205, New Haven, CT 06520-8205, USA.e-mail: Paul.Bloom@yale.edu

TRENDS in Cognitive Sciences Vol.6 No.12 December 2002

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Gardens of paradise by Staffan Müller-WilleCrookes, carbolic and cattle plague by William H. Brock

Benjamin West’s portrait of Joseph Banks by Patricia FaraHumphrey Davy: science and social mobility by David M. KnightBritish cell theory on the eve of genetics by Marsha L. Richmond

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Erratum

In the November issue of TICS, therewas an error in the Review entitled‘The prefrontal cortex in sleep’, by A. Muzur, E.F. Pace-Schott andJ.A. Hobson. (Trends in CognitiveSciences, Vol. 6, p. 475).

In the abstract, NREM wasincorrectly defined asnonrandom-eye-movement.It should of course have read:

During nonrapid-eye-movement

(NREM) sleep, frontal cortical activity is

characterized by the highest voltage

and the slowest brain waves compared

with other cortical regions.

We apologize to the authors andreaders for this error.

PII: S1364-6613(02)02042-9