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Principles of Categorization 265

to be understood (see Miller 1978). That is, it appeared that the analysis of
objects into attributes was a rather sophisticated activity that our subjects (and
indeed a system of cultural knowledge) might well be considered to be able to
impose only after the development of the category system.
In fact, the same laws of cognitive economy leading to the push toward basic-
level categories and prototypes might also lead to the definition of attributes
of categories such that the categories once given would appear maximally
distinctive from one another and such that the more prototypical items would
appear even more representative of their own and less representative of con-
trastive categories. Actually, in the evolution of the meaning of terms in lan-
guages, probably both the constraint of real-world factors and the construction
and reconstruction of attributes are continually present. Thus, given a particu-
lar category system, attributes are defined such as to make the system appear
as logical and economical as possible. However, if such a system becomes
markedly out of phase with real-world constraints, it will probably tend to
evolve to be more in line with those constraints—with redefinition of attributes
ensuing if necessary. Unfortunately, to state the matter in such a way is to
provide no clear place at which we can enter the system as analytical scientists.
What is the unit with which to start our analysis? Partly in order to find a more
basic real-world unit for analysis than attributes, we have turned our attention
to the contexts in which objects occur—that is, to the culturally defined events
in which objects serve as props.

The Role of Context in Basic-Level Objects and Prototypes
It is obvious, even in the absence of controlled experimentation, that a man
about to buy a chair who is standing in a furniture store surrounded by differ-
ent chairs among which he must choose will think and speak about chairs at
other than the basic level of ‘‘chair.’’ Similarly, in regard to prototypes, it is ob-
vious that if asked for the most typical African animal, people of any age will
not name the same animal as when asked for the most typical American pet
animal. Because interest in context is only beginning, it is not yet clear just
what experimentally defined contexts will affect what dependent variables for
what categories. But it is predetermined that there will be context effects for
both the level of abstraction at which an object is considered and for which
items are named, learned, listed, or expected in a category. Does this mean that
our findings in regard to basic levels and prototypes are relevant only to the
artificial situation of the laboratory in which a context is not specified?
Actually, both basic levels and prototypes are, in a sense, theories about
context itself. The basic level of abstraction is that level of abstraction that is
appropriate for using, thinking about, or naming an object in most situations in
which the object occurs (Rosch et al. 1976a). And when a context is not speci-
fied in an experiment, people must contribute their own context. Presumably,
they do not do so randomly. Indeed, it seems likely that, in the absence of a
specified context, subjects assume what they consider the normal context or
situation for occurrence of that object. To make such claims about categories
appears to demand an analysis of the actual events in daily life in which objects
occur.