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Next Previous Table of content6. Visions of the pioneer
Herbert A. Simon began
his academic career in the 1940s as a professor for political sciences,
before in 1949 he took over the chair for computer science and psychology
at Carnegie Mellon university which he holds until today. His excellence
in many fields is proven by the fact that, in 1978, he received the
Nobel price for economic science - although he does not have anything
to do, formally, with this academic discipline. But Herbert Simon was
always a man who had no interest in academic boundaries. He is not necessarily someone
who can be called reluctant about his role. Asked about "cognitive
revolution" in an interview, he answered briefly: " You might
say that we started it." (Baumgartner and Payr, 1995, p. 233) With "we" he referred
to himself and his partners,
Alan Newell and J.C. Shaw. Together with them, Simon had developed between
1955 and 1957 a computer program called "Logic Theorist" (LT)
which should prove theorems by heuristic search. From LT grew GPS, the
General Problem Solver, developed by Newell, Shaw and Simon between
1957 and 1959. GPS was the first
computer program which had been expressly developed in order to simulate
human problem solving processes. With it, Simon and his colleagues broke
new ground at a time in which behaviourism dominated. At the same time
they laid the founding stone for a number of further attempts to understand
the functioning of the human mind with the help of computers. In the year 1967, Herbert
Simon published in the Psychological Review an essay under the title
"Motivational and Emotional Controls of Cognition" (Simon, 1967). In
it, he regarded for the first time emotions as part of a systematic modelling
approach of cognitive processes. The work was a reaction
to an article of Ulric Neisser. Neisser expressed therein his criticism
of existing or planned computer programs as follows: "Three fundamental and interrelated
characteristics of human thoughts...are conspicuously absent from existing or
contemplated computer programs: Simon accepted the
objections of Neisser and saw his own work as an attempt to create a first
theoretical basis for the construction of an information-processing system
which has emotions and multiple goals. Neisser and other
critics of the computer modelling of mental processes had, among other
things, pointed out that these have only little to do with human behaviour.
Such programs, they argued, would pursue, for example, only a simple
goal and not, like humans, be propelled by numerous motives. For Simon this argument
was not sound. He granted that the implemented models were "excessively
simplified" (Simon, 1967, p. 34); but this were due to technical
requirements. The models behind such programs of a hierarchically arranged,
serial information processing were not so linear however: "Activity towards specific goals is
terminated by aspiration, satisficing, impatience, and discouragement
mechanisms; distinct tasks may be queued or handled within individual time
allocations; choices among alternatives may respond to multiple
criteria." At the same time, Simon knew that such a model lacked certain features: "The mechanisms we have considered are
inadequate to deal with the fact that, if the organism is to survive,
certain goals must be achieved by certain specified times." What is missing in the
past models is clear to him: A mechanism which can, at any given time,
"hijack" the attention in order to use it for survival-related
goals. "If real-time needs are to be met, then provision must be made
for an interrupt system." (Simon, 1967, p. 34) Simon then develops a
theory of such an interrupt system. First he defines three classes of real
time needs of an individual. Needs arising from uncertain environmental
events are, for example, sudden noises or visual stimuli which could
signal a danger. Physiologigal needs are internal stimuli which announce
physical needs, for example hunger, thirst, exhaustion etc.. Cognitive
associations are, finally, strong stimuli which are released by memory
associations, for example an unspecified fear. These real time needs
are, according to Simon, accompanied by a number of physiological phenomena
as well as by subjective feelings, which accompany generally also the
states which are called "emotion". As interruptor,
such an emotional stimulus fulfills a substantial survival function
by interrupting current processing processes and directing the attention
on a problem more urgent for the survival of the individual. Under certain
circumstances, however, the interruptor can change into a disruptor
which possesses no adaptive value whatsoever. An important quality of
the interrupt system is that it can be changed by learning. "In two ways, then, we may expect
learning to reduce the emotionality of response as a situation becomes more
familiar: (a) The need for interruption is reduced by incorporation of more
elaborate side conditions in the programs associated with ongoing goals; (b)
the response to interruption becomes more successfully adaptive, thus
forestalling new interruptions." As a result of his
reflections, it is clear for Simon that close-to-reality and promising
theories of human cognition must include emotions in the form of an
interrupt system. Simon summarizes his
theory as follows: "The theory explains how a basically
serial information processor endowed with multiple needs behaves adaptively
and survives in an environment that presents unpredictable threats and
opportunities. The explanation is built on two central mechanisms: 1. A goal-terminating
mechanism [goal executor]...2. An interruption mechanism, that is, emotion,
allows the processor to respond to urgent needs in real time." The theory implies that
organisms have two parallel processing systems: a "goal executor"
which generates actions and a "tracking system" which continuously
monitors the internal and external environment of an organism for an event that
requires a quick reaction. The first, resource-limited system, can be interrupted
by the second. With his work Simon
defined a number of substantial corner stones which are of importance for the
further development of autonomous systems. Such systems are propelled by different
motivations, which can develop due to changing external or internal states. Due
to the fact that such systems have only limited resources, but are existing
in a complex and, to a large extent, unpredictable environment, they need a
system of control structures which make it possible for them to interrupt
current processes and initiate new ones if this is of importance for the survival
of the system. Simon limits his considerations
quite deliberately not to humans or animals, but does regard them as
design requirements for each autonomous system. So it is certainly no
coincidence that his central mechanism is the interrupt, a term which
is used in similar form also in computer science. Sloman (1992) interprets
Simon's remarks expressly as instructions for the construction of autonomous
systems: "He outlines some of the control issues,
and suggests suitable mechanisms, inspired in large part by developments in
computer science and AI, including software techniques for generating new
sub-goals at run time, techniques for queueing and scheduling processes,
techniques for forming plans in order to achieve goals, techniques for
assigning priorities and resolving internal conflicts, and techniques for
generating and handling interrupts." Next Previous Table of content
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