empirical view of one of psychology's most fundamental topics. Of course, by def-
inition, none of us can see our own blind spots, so I am certain that many readers
will see biases, especially if the information provided or the way it is presented
does not agree with their own favored point of view. Following the publication of
previous editions of this book, I received mail from many readers--some praising
my fair-mindedness and the clear way in which I presented information (funny, but
I remember these the best), but others taking exception to the way a particular area
of research or theory was interpreted. I was pleased to find that the criticisms came
from all ends of the political spectra, which I interpreted to mean that I had done a
fairly good job of angering all sorts of people. In other words, I had succeeded at
interpreting the hug and diverse literature. I hope that this edition comes even
closer to achieving that goal.

The years since the publication of the second edition of Sex Differences in Cog-
nitive Abilities have seen an explosion of new theories and research into the many
questions about sex differences in cognition. New techniques for peering into the
human brain have changed the nature of the research questions that we can ask and
the kinds of answers we can expect. There have been surprising new findings about
the influence of sex hormones throughout the life span for both women and men.
Readers are warned that the burgeoning area of cognitive neuroscience is still in its
own perinatal period, which means that inferences about the brain bases of cogni-
tion are extremely fragile and likely to change as the field develops. There has also
been a rapid increase in the number of studies that examine unconscious and auto-
matic processes that influence how people think when they become aware of cate-
gory variables like one's sex, race or age. The important advance since the
publication of the second edition of this book is the renewed emphasis on the conti-
nuity of environmental and biological variables, a perspective that blurs the di-
tinction between these two types of influences. The psychobiosocial model that I
advocate discards the nature-nurture dichotomy and replaces it with a continuous
feedback loop in which nature and nurture are inseparable. I hope that this
reconceptualization of the variables that influence who we are and how we develop
will move us away from the nature-nurture tug-of-war to a more holistic and recip-
rocal view of human cognitive development.

My sincere thanks goes to those unsung heroes who have read and commented on
some or all portions of this book as it progressed through numerous drafts. I am
enormously grateful for the insights of Dr. Marcia Collear at Middlebury College,
Dr. Ann Gallagher at the Educational Testing Service, and Dr. George Spillach at
Washington College. I also thank numerous students who have helped with this
edition especially (soon-to-be-Ph.D.) Mary LaMay at Loma Linda University.
Each of these special people provided encouraging feedback and helpful ideas
throughout the writing process.

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