80 Comparative Psychology
sophisticated but has begun to creep back into the field as
some believe that the most remarkable feats of animals cannot
be produced under controlled conditions but require unusual
circumstances. Comparative psychologists have devoted
much attention to the construction of apparatus appropriate to
the problem at hand (Warden et al., 1935; D. A. Washburn,
Rumbaugh, & Richardson, 1998).
The theory of evolution has provided the conceptual foun-
dation of psychology since its founding. At times, it has been
in the foreground, as in the early work of James, Angell, Hall,
and James Mark Baldwin (1896), who along with two others,
proposed the “Baldwin effect” as a means to explain apparent
inheritance of acquired traits with more conventional evolu-
tionary principles. Another examples is the APA presidential
address of Calvin Stone (1943). At other times, it has been
more implicit. Although the evolutionary focus of compara-
tive psychology was not obvious to some observers during
parts of the history of the field, the strong evolutionary ap-
proach has been increasingly visible since World War II.
Surely the most persistent issue in comparative psychol-
ogy, and perhaps for all psychology, has been the nature-
nurture problem. Throughout its history the pendulum has
swung back and forth between emphases on genes and envi-
ronment in the development of behavior. Such psychologists
as William James and William McDougall postulated many
instincts in humans and other species. This led to an anti-
instinct revolt that was particularly strong during the 1920s.
Virtually all comparative psychologists now recognize the
importance of the continuous, dynamic interaction of genes
and environment in the development of behavior. Some, such
as Yerkes, Stone, Robert Tryon, and Jerry Hirsch, have con-
ducted important studies of genetic influences. Such psychol-
ogists as Harlow, Eckhard Hess, and Gilbert Gottlieb have
worked more on experiential factors. Virtually all agree on
the importance of the dynamic interaction of both.
A key part of the nature-nurture problem is that problem
of instinctive behavior. The fact is that individuals of many
species develop either specific motor patterns or responsivity
to specific stimuli in the absence of specific experience. For
example, young sea turtles hatched on a beach in the absence
of adults go toward the ocean, not the dune (Mellgren &
Mann, 1998). The environment is critical for all behavior but
appears not to provide the specificity in such instances.
Whatever one may call it, the ontogeny of such behavioral
patterns appears different, at least to some degree, from the
ontogeny of many other behavioral patterns. Comparative
psychologists still grapple with the problem of explaining
such behavior.
Sensory-perceptual systems provide the stimuli for virtu-
ally all behavior and have been of interest in comparative
psychology throughout its history. Six of the 13 chapters in
M. F. Washburn’s (1908) textbook were devoted to sensory
systems. Watson, Lashley, Hess, and many others have
contributed in this endeavor.
Many studies of basic behavioral patterns have been con-
ducted. Included are such topics as orientation, activity, in-
gestive behavior, hoarding, nest building, exploration, and
play. Many comparative psychologists have studied social
behavior and imitation.
For sheer quantity of research articles, the study of learning
may exceed all other problems in comparative psychology.
Almost all comparative psychologists have conducted at least
some research related to learning. Many studies have been of
single species. Some, such as Bitterman (1965), Gossette
(Gossette & Gossette, 1967), and Rumbaugh (Rumbaugh &
Pate, 1984), have attempted systematic comparisons using
particular learning problems. In recent years, many compara-
tive psychologists have viewed learning in relation to the de-
mands of the specific habitats in which the study species has
evolved (e.g., Shettleworth, 1998). The question concerning
the existence of a general learning process versus domain-
specific mechanisms is actively debated.
At least from the time of Thorndike, the issue of animal
cognition has been central. Is all learning the product of basic
mechanisms, or are higher processes sometimes required to
explain changes in animal behavior, as suggested by Köhler,
Maier, and many recent cognitive psychologists and etholo-
gists? Most of the issues addressed in the flourishing field of
comparative cognition were also addressed, in one form or
another, by earlier generations. In recent years, work based
on the assumption that higher processes are operative has led
to many fascinating findings in comparative psychology, in-
cluding investigations based on a theory of mind (Premack &
Woodruff, 1978), of production and comprehension of refer-
ential pointing (Call & Tomasello, 1994), and those suggest-
ing that “chimpanzees are capable of modeling the visual
perspectives of others” (Povinelli, Nelson, & Boysen, 1990).
Such results suggest that, at the very least, these cognitive ap-
proaches might be of considerable heuristic value.
Throughout its history, comparative research, from Ivan
Pavlov and John B. Watson to the present, has been attacked
by animal activists of one sort or another (Dewsbury, 1990).
Recent studies of animal cognition have produced an ironic
twist. Some of the very research that activists condemn has
revealed remarkable abilities in animals and similarities to
humans that the activists then use to argue for the cessation of
that research because of that similarity to humans.
Related to the issue of cognition is that of animal con-
sciousness. In this area there seems to have been little
progress since the days of Morgan (1894) and M. F.
Washburn (1908). I see in many species, especially pri-
mates, behavior that, in myself, is correlated with certain