In Preference, Belief and
Similarity, Eldar Shafir has cleverly assembled a representative array of
articles written by Amos Tversky, a cognitive psychologist well-known for his
work on judgment and decision making who died in 1996. As a measure of his influence
in the field of psychology and beyond, it is noteworthy that Tversky and his
colleague of nearly three decades, Daniel Kahneman, were bestowed the 2003 Grawemeyer
Award for Psychology.  Not surprisingly, Kahneman was awarded the Nobel Memorial
Prize in Economic Sciences in recognition of the work he had accomplished with
Tversky. Thus, even though the Royal Swedish Academy of Sciences was unable to
bestow the prize on Tversky posthumously, it did not neglect to acknowledge his
contribution to the field of Economics. Besides these prestigious recognitions
and others obtained earlier during his productive career as a cognitive
scientist, it is worth mentioning that Tversky’s articles regularly receive
high ratings in the Social Science Citation Index and his name appears in a
list of highly cited researchers posted on the internet by the Institute for
Scientific Information.   

Eldar Shafir’s selection of papers
generated by Tversky illustrates the most important aspects of his extensive contribution
to the fields of judgment and decision making, a contribution often linked to
his long-term collaboration with Kahneman.  Not surprisingly, one of Kahneman
and Tversky most important insights into the human mind was that everyday
judgments and decision making processes and outcomes more often than not
violate normative principles of probability.  Nevertheless, they argued that
the study of such deviations in the form of biases and systematic errors could
reveal the intuitive principles and information upon which such judgments are
made.  Thus, judgments and decisions in naturalistic settings could be thought
of as predictable phenomena governed by a clearly specified set of principles. 
These insights and others, along with flawless experimental demonstrations and
highly compelling practical illustrations have contributed to the success of
the work of Tversky and Kahneman not only in psychology but also in economics,
an area that has been traditionally outside the reach of psychological research.
  

 To illustrate the breath of Tversky’s
work, the selection made by Eldar Shafir of relevant articles is divided into
three sections: similarity, judgment, and preference.  Unquestionably, the
selection is comprehensive and well thought-out.  It provides readers with a
descriptive illustration of the main tenets of Tversky’s work along with a much
needed chronological frame of reference.  

The first section features Tversky’s
well-known model of similarity.  Not surprisingly, although this model is based
on elementary psychological assumptions about how objects are represented in
the human mind and how such representations are used in judging likeness and
diversity, it provides an elegant and comprehensive account of how everyday
judgments of similarity and dissimilarity are reached.  Several articles build
on the model and give it a more detailed specification with discussions on the
adequacy of geometric representations for perceptual and conceptual data, and
on the role of common and distinctive features in judgments of verbal and
pictorial data.

In the section on judgment, the work on heuristics
and cognitive and perceptual biases is discussed at length.  This work reflects
Tversky’s acknowledgment that intuitive predictions and judgments of probability
heavily rely on heuristics, which are rules of thumb that provide people with
quick and coherent answers to a given problem even though they can also lead to
remarkable errors.  His insightful analyses of different types of heuristics
such as representativeness, availability, and anchoring are priceless, and his
fascinating observations on how they are used in everyday settings provide
readers with an unparalleled means for recognizing that scientific inquiry and
its findings may be pertinent to their own lives.  No less relevant are Tversky’s
criticism of normative theories and the ensuing development of support theory. 

In the section on preference, the focus is on
decision making.  It begins with Tversky’s criticism of traditional
probabilistic models of choice and his belief that failures to yield optimal
choices are systematic and that their study can lead to the understanding of
the psychological processes that preside over choice behavior.  Even in this
area, Tversky generated a theoretical framework to account for decision making
patterns that can be empirically observed.  This framework questioned the
assumption of "homo oeconomicus", that is, of human beings motivated
by self interest and capable of rational decision making behavior. Of relevance
here, is the elimination-by-aspects model, which guided Tversky’s
interpretation of observed dependencies among available options, and prospect
theory, a model of decision making under uncertainty as well as in cases of
risky choices.  As expected, studies documenting the occurrence of biases such
as framing and certainty effects in realistic settings are no less remarkable.

In summary, the book is an
illustration of Tversky’s impressive contribution to the scientific study of
everyday human judgments and decision making processes.  Not surprisingly, the Royal
Swedish Academy of Sciences has praised the work of Tversky and Kahneman for "having
integrated insights from psychological research into economic science".  Ingrained
in this tribute, it is the recognition that their work initiated a new field of
scientific inquiry, behavioral economics, which called into question the most
basic assumptions of traditional economic science. Certainly a must-read book
for anybody who has an interest in understanding how great ideas about the
functioning of the human mind can account for everyday behavior.

© 2004 Maura Pilotti

Maura Pilotti,
Ph.D., Department of Psychology, Dowling
College, New
York.

Categories: Psychology