joyed most the math and physics and
chemistry. So why electrical engineering, as opposed to going into physics?
Around my family, no one had ever
heard of a thing called a physicist. In
this middle-class to lower-middle-class culture people were focused on
getting a job that would make money,
and engineers could get jobs and make
I happened to see an advertisement for scholarships being offered
by an engineering school in Pittsburgh
called Carnegie Institute of Technology. I got a scholarship, so that’s what
I did. Life is an interesting set of choices, and the decision to go to Carnegie
Tech (now Carnegie-Mellon University) was a fantastically good decision.
Something else there got you excited.
I had a nagging feeling that there was
something missing in my courses.
There’s got to be more to a university
education! In the catalog I found a really interesting listing called “Ideas
and Social Change,” taught by a young
new instructor, James March. The first
thing he did was to expose us to Von
Neumann’s and Morgenstern’s “
Theory of Games and Economic Behavior.”
Wow! This is mind-blowing! My first
published paper was with March in social psychology, on decision-making in
March introduced me to a more senior and famous professor, Herbert
Simon. That led to my taking a course
from Simon called “Mathematical
Models in the Social Sciences.” I got to
know Herb, and got to realize that this
was a totally extraordinary person.
In January 1956 Herb walked into
our seminar of six people and said
these famous words: “Over Christmas
Allen Newell and I invented a thinking machine.” Well, that just blew our
minds. He and Newell had formulated
the Logic Theorist on December 15th,
1955. They put together a paper program that got implemented in the language called IPL- 1, which was not a language that ran on any computer. It was
the first list processing language, but it
ran in their heads.
That led to your first
exposure to computers.
When we asked Herb in that class,
“What do you mean by a machine?”
he handed us an IBM 701 manual, an
early IBM vacuum tube computer. That
was a born-again experience! Taking
that manual home, reading it all night
long—by the dawn, I was hooked on
computers. I knew what I was going
to do: stay with Simon and do more of
this. But Carnegie Tech did not have
any computers at that time, so I got a
job at IBM for the summer of 1956 in
What did you learn at IBM?
First, plug board programming, which
was a phenomenally interesting thing
for a geeky kid. Second, the IBM 650,
because by that time it became known
that Carnegie Tech would be getting a
650. Third, the IBM 704, which was a
successor machine to the 701.
When I got back to Carnegie Tech
in September 1956 and began my
graduate work, there was Alan Perlis, a
wonderful computer genius, and later
the first Turing Award winner. Perlis
was finishing up an amazing program
called a compiler. That was “IT,” Internal Translator, and it occupied 1,998
words of the 2,000-word IBM 650 drum.
I had known about the idea of algebraic languages because in the summer
at IBM someone had come down from
the fourth floor to talk to the graduate
students and tell them about a new
thing that had just hit the scene. You
didn’t have to write “CLA” for “clear
and add,” and you didn’t have to write
“005” for “add.” You could write a formula, and a program would translate
that formula into machine language.
FOR-TRAN. The guy was John Backus,
this idea has been
for my career—
as opposed to the
who had come downstairs to talk to
us. IT’s introduction actually preceded
Fortran’s by about nine months.
What was it like to use
a computer then?
There was no staff between you and the
computer. You could book time on the
computer, then you went and did your
thing. A personal computer! I loved it.
I loved the lights, I loved pressing the
switches. This idea has been very important for my career—the hands on,
experimental approach to computer
science as opposed to the theoretical
approach. Experiment turns out to be
I was able to write a rather complicated—for that time—simulation of
two companies engaged in a duopolis-tic decision-making duel about pricing of tin cans in the can industry, the
second such simulation of economic
behavior ever written. It led to my first
conference paper, in December 1958,
at the American Economics Association annual meeting.
What did you do for your dissertation?
A model called EPAM, Elementary Perceiver and Memorizer, a computer simulation model of human learning and
memory of nonsense syllables.
I invented a data structure called a
Discrimination Net—a memory structure that started out as nothing when
the learner starts. List structures had
just been invented, but no one had
tried to grow trees. I had to, because
I would start with two nonsense syllables in the Net, and then the next
pair would come in and they’d have to
“grow into” the net somewhere. These
were the first adaptively growing trees.
Now here’s an amazing and kind of stupid thing that shows what it means to
focus your attention on x rather than
y. We were focused on psychology. We
were not focused on what is now called
computer science. So we never published anything about those adaptively
growing trees, except as they related
to the psychological model. But other
people did see trees as a thing to write
papers about in the IT literature. So I
missed that one!
Where was your first academic job?
I had wanted to come to the West
Coast, and the University of California