A Cross-Cultural Research
Contribution to Unraveling the
Nativist/Empiricist Controversy
MARSHALL H. SEGALL
The premise that the world is what it appears to be
was challenged many centuries ago by Plato (circa
390 BC) in his famous parable of the cave (Republic
7). According to the parable, people are imprisoned
in the cave, able to see only shadows and reflections
of what transpires about them. Plato's point was
that the prisoners will take these shadows for reality. If the prisoners are released and directly witness
the events that are casting the shadows, Plato said,
the objects and events will appear less real than
their reflections.
Other philosophers followed Plato in warning
against naive realism-the widespread tendency of
us mortals to assume that the world is as it appears,
a tendency reinforced by the apparent clarity, constancy, and "thing-ness" of the content of most of
our perceptions. To us, objects seem solid, despite
all the space contained in every atom of any object.
Marshall H. S e e l l began his career in cross-cultural psychology in the 1950s, influenced by Donald
Campbell, Melville Herskovits, Otto Klineberg,
Leonard Doob, and Jean Piaget. Spending most of his
career at Syracuse University, in the Maxwell School,
and as Associate Dean of Arts and Sciences, he now
lives in France where he directs the Syracuse program
in Strasbourg. He has done research and taught in
Europe and Africa. His recent cross-cultural textbooks,
written with Pierre Dasen, JohnBerry, and Ype Poortinga, are being translated into several languages.
In other ways, too, the world is clearly not just the
way it seems to be.
When stimulation changes, sometimes the related perception does not. The perception of the
size of persons, viewed from nearby or from far
away, is a good example. The stimuli, images on our
retina, differ across distance; the perceived size
does not. The fact that judgments of a varying
stimulus may remain constant over a wide range of
variation is a phenomenon that long ago was
dubbed "perceptual constancy." Two main schools
of thought have been developed to account for this
phenomenon: nativism and empiricism.
Nativism includes any theory that attributes
perceptual phenomena, including constancy, to the
way the human nervous system is structured. Nativistic theories thus give much importance to inborn (or native) characteristics and, consequently,
they give little importance to experience.
By contrast, empiricist theories deem experience
to be critical in shaping the way we perceive. They
believe that perception is neither stimulus-determined nor forced by the p r e - w i d nature of the
human nervous system. They attribute to perceivers a very active role in shaping their own perceptions. Each person is considered to be an active
player in perception, with the perceiver's state at
the time a product of the perceiver's prior experiences. Every perception, then, is the result of an
interaction between a stimulus and a perceiver
shaped by prior experience.
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1 9 / A Cross-Cultural Research Contribution to
Unraveling the NativisVErnpiricist Controversy
One large-scale test of an empiricist theory of
visual perception was done in the 1950s and 1960s
by a team of psychologists and anthropologists
(Segall, Campbell, & Herskovits, 1963; 1966). The
study involved several geometric drawings, long
known as optical illusions, and was conducted in
more than fifteen societies, some in the United
States and most in Africa. The researchers used illusions in this study primarily because some wellknown nativist theorists (e.g., Gestalt psychologists
in late 19th-century and early 20th-century Germany) explained them as virtuilly inevitable consequences of the way the human visual system was
constructed. In short, to nativists, illusion susceptibility reflected inborn ways of perceiving. According to such nativist theorizing, all humans should
be more or less equally susceptible to optical illusions, unless, of course, various humans had different kinds of nervous systems.
Segall and colleagues were skeptical of such
nativist theorizing. They were influenced by an exceptional German-born psychologist, Egon Bmnswik, who had asserted, in 1956, that all perception
involves functional transactions between a viewer
and the incoming sensory matter. These transactions are "functional" in the sense that they lead to
perceptions that contribute to the organism's sur-
All perception involves functional
transactions between a viewer and
the incoming sensory matter.
viva1 (by usually being accurate!). Elaborating on
Brunswik's thinking, Segall and colleagues argued
that theremight well be cross-cultural differencesin
illusion susceptibility. Why did they think so? Because responses to illusion-producing figures,
which have the potential for varying interpretations, might reflect learned ways to interpret inherently ambiguous cues. They reasoned that if people
who grow up in different environments do learn to
interpret cues differently, there should be ecological
and cultural differences in perception of any ambiguous stimuli. The so-called optical illusions are
good examples of ambiguous stimuli.
This line of reasoning is demonstrated most
easily with a figure known as the Sander parallelo-
gram, an example of which is shown in Figure 1.
They explained this "illusion" by a particular version of Bmnswikian theorizing, known as the "carpentered-world hypothesis." In the earlier research
literature reporting laboratory research with illusions, most people who viewed this figure judged
the left diagonal as longer than it really is and the
right diagonal as shorter than it really is. Before the
Segall et al. research, nearly all participants in research of this kind were university students residing in Europe or America. If the present reader lives
in a carpentered environment, she, too, is likely to
fall prey to this illusion.
This bias, or error, is understandable, according
to the empiricists, as the result of a tendency to
perceive the parallelogram, drawn on a flat, two-dimensional surface as if it were meant to represent a
rectangular surface extended in three-dimensional
space. Hence, the viewer judges the distance covered by the left diagonal as greater than the distance
covered by the right diagonal.
The judgment, which produces an error in this
case, is one that normally leads to accurate perception in environments that contain rectangular objects, especially rectangular tables. Put another way,
"this judgment reflects a habit of inference that has
ecological validity in highly carpentered environments" (Segall, Dasen, Berry, & Poortinga, 1990).
Since people who live in places with tables usually
see them from points of view that generate non-rectangular, parallelogram-shaped retinal images,
complete with acute and obtuse angles at each corner, they must learn that the tables are to be perceived as rectangular, with 90 degree comers.
Imagine that the parallelogram shown in Figure 1 was intended to be a representation of a ping
pong table top, seen from above, but from a somewhat rakish angle. If it were, and the center diagonal were meant to be the net, then consider how
much longer the distance represented by the left
diagonal is compared to that represented by the
right diagonal. The Sander parallelogram is an "illusion" when it is taken to be a representation of a
table top in three-dimensional space instead of
FIGURE 1 The Sander parallelogram illusion
1 9 / A Cross-Cultural Research
Contribution to Unraveling the NativisVEmpiricist Controversy
merely a parallelogram on a two-dimensional surface (which it actually is)!
Inferring that acute and obtuse angles in retinal
images are nearly always coming from right angles
on objects in the environment is a functional habit
of inference for people who live in carpentered
worlds. This functional habit, empiricists argue,
makes these same people susceptible to optical illusions like the Sander parallelogram.
It should now be clear why the team of researchers decided to collect data cross-culturally.
While in carpentered settings, the tendency to interpret acute and obtuse angles as right angles is pervasively reinforced, there are places on earth where
right angles are rare (non-carpentered environments), and the habit of interpreting acute and obtuse angles as right angles extended in space would
not be so readily acquired. Hence, people in carpentered worlds should be relatively susceptible to illusions like the Sander parallelogram while persons
in non-carpentered worlds, far less so. In short, specific cross-cultural differences in illusion susceptibility are predicted by this empiricist line of
reasoning, while nativism makes no such prediction.
The carpentered world hypothesis is only one
of several empiricist hypotheses that were derived
from the general line of afgument. The various hypotheses all predicted cross-cultural differences in
illusion susceptibility on the basis of different
learned habits of inferenceifferent, but in all
cases ecologically valid.
To test these ideas, a standard set of stimulus
materials were administered by a dozen researchers
to a total of 1,848 persons, children and adults, living in several African countries, in the Philippines,
and in the United States. The materials included the
Sander parallelogram, described above, the MullerLyer illusion, and two forms of the horizontal/vertical illusion. This particular set of illusions was
employed because people living in the United
States were expected to be more susceptibleto some
of the illusions, than, say, people living in Africa,
while for other illusions, the reverse was predicted.
Predicting differencesin both directions was one of
the methodological niceties of the research design.
It took six years for the data to be collected,
analyzed, and presented in a book-length report
(Segall, Campbell, & Herskovits, 1966). The findings, in a nutshell, were that the predicted differences in illusion susceptibility were indeed found.
There were marked differences in illusion susceptibility across the cultural groups included in this
137
study and these differences accorded well with the
empiricist theory that attributes perceptual tendencies to ecologically valid inference habits.'
This empiricist position, despite its support
from the cross-cultural data, did not long go unchallenged, however, from the nativist camp. Pollack (1970) was aware of laboratory findings (some
of them from his own laboratory) that persons with
relatively dense retinal pigmentation (who are usually dark-skinned persons) have more trouble detecting contours in visual stimuli. Arguing that
contour detectability might be an aspect of susceptibility to some illusions (especially the MullerLyer), and noting that the non-Western samples
employed in the Segall et al. study were mostly
African peoples, Pollack suggested that "race"
might be the real explanation for what had been
presented as ecocultural differences.
A comment on the concept of "race" is needed
here. Quotation marks (inverted commas) are used
to indicate that the concept "race" is merely a social
construct and not the biologically precise term it is
usually taken to be. When Pollack spoke of race, he
was in fact referring to people of European or African origin, with relatively light or relatively dark
skin. Someday, it is hoped, the fuzziness of the concept will be generally understood, and people will
cease attributing differences so offhandedly to such
an ill-defined construct.
Anyway, Stewart (1973) made clear that Pollack's challenge to empiricist theory called for a
dual research strategy, in which one first holds environment constant while allowing "race" to vary,
and then testing across environmentswhile holding
"race" constant. So, first she administered the
Sander parallelogram and the Muller-Lyer illusions
to 60 "Black" and 60 "White" schoolchildren in
Evanston, Illinois. She found no significant differences in susceptibility between the two groups.
Then, she administered the same materials to Zambian schoolchildren, all of them "Black" Africans,
but living in five different places in Zambia, ranging from the highly carpentered capital city, Lusaka,
'Students who would like more detailed accounts of the findings
may consult Segall, Campbell, & Herskovits, 1966, for the most
complete story of this project or Segall, Dasen, Berry, & Poortinga,
1990 (pp. 76-83), for a concise summary. Another excellent summary, embedded in a thorough review of crosscultural research
on many different kinds of perceptual topics, may be found in
Berry, Poortinga, Segall, & Dasen, 1992 (pp. 147-149). Since these
three accounts (and others) are readily available, and since space
in the present volume is limited, no more will be said here about
the findings of the original study.
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1 9 / A Cross-CulturalResearch Contribution to Unraveling the NativisVErnpiridst Controversy
to a very un-carpentered Zambezi Valley region.
For both illusions, susceptibility varied positively
with increases in the degree of carpenteredness of
the five sites in Zambia. The combined data from
Evanston and Zambia showed that susceptibility to
both illusions increases with increasing carpenteredness whereas "race" mattered not at all!
During the subsequent decades of the 20th century, there have been several other cross-cultural
studies of illusion susceptibility and of closely related kinds of perceptual processes, such as pictorial perception (see, for example, Deregowski, 1980
and Serpell & Deregowski, 1980). These all contribute support to the empiricist side of the nativist/empiricist controversy. Illusion susceptibility
does, after all, appear to be a reflection of learned
habits of inference that are always ecologically
valid.
The point of all this theorizing and research
was not merely to explain optical illusions. Rather,
it was to explain how it is that human beings see the
world as they do. Illusions were studied in this
particular line of research because they were
thought to constitute a special class of ambiguous
stimuli that would reveal differences grounded in
basic sameness. Thus, almost paradoxically, the
cross-cultural differences that were predicted
(and found) demonstrate the operation of fundamental perceptual processes, shared by human beings everywhere.
Nativism argues that human beings behave in
ways that are largely predetermined by the nature
of their anatomy, physiology, and, especially, their
nervous systems. So, if groups of people behave
differently,one group from the other, nativists tend
to attribute these differences to differences in the
nature of the groups. The human species then is
viewed as if it comprised distinct and distinctly
different subgroups, of which "races" have so tediously been considered prime examples. By contrast,
empiricism argues that we are fundamentally all
one species. We all learn from experiences. What
varies across environmental settings is the kinds of
experiences we have. So we learn different things.
So we behave differently. But we are not different
beings. Is the lesson that has been learned from
cross-cultural research on optical illusions one that
can help humankind learn to live as one?
A final note. This chapter was written in Strasbourg, France, on the first day of January, 1993, the
day that the European Common Market came into
official being. On this day also, what was once
Czechoslovakia divided into two, and what was
one Yugoslavia remained splintered into warring
factions. Consciousness of ethnicity, a view of the
world in which it appears divided into "us" and
'them," competes with a view of the world as one.
Those who advocate programs of "ethnic cleansing" are nativists in the extreme. Those who hold to
the dream of a unified Europe and ultimately to a
world containing only one people are empiricists.
So,a little reflection can make it clear that this chapter is not, after all, about such a small matter as
optical illusions.
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