6. 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
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."