E85.2042 Psychology of Music
January 29, 2008 - Foundations of Cognitive Science
Behaviorism
1) "those researchers interested in a science of behavior ought to restrict themselves strictly to public methods
of observations, which any scientist could apply and quantify." 2) "those interested in a science of behavior ought
to focus exclusively on behavior: researchers ought assiduously to eschew such topics as mind, thinking, or imagination and
such concepts as plan, desires, or intentions." [Gardner p. 11]
Behaviorists believed that reflexive responses could explain human activity just as classical mechanics explained physical activity.
Behaviorism held that psychology should study the relationships between stimuli and responses,
without reference to desires, plans, concepts, etc. "During the high tide of behaviorism, experimental psychology
focused on relatively simple cognitive performance, with emphasis on sensory and motor processes such as rote verbal
learning, tracking tasks requiring hand-eye coordination, memory tasks involving relatively short-term retention, and
the attainment of simple concepts. The intelligence of rats and pigeons received as much attention as the intelligence
of people" [Simon & Kaplan p. 3].
Norbert Weiner coined the term cybernetics to describe the use of feedback as a mechanism to explain
the ability of natural and artificial systems to adjust their behavior.
Boolean truth tables
George Boole introduced the "laws of thought" in 1854. Given propositions with truth values, Boole proposed
expressions that would show the truth value of combinations of these propositions.
Logic
Propositional logic represents relationships between propositions, such as p = paula is in the library,
and q = quincy is in the library. Then p -> q indicates that if paula is in the library, then quincy is
in the library. "Predicate calculus distinguishes between predicates such as 'is a student' and constants referring to
individuals such as Paula or Quincy" [Thagard p. 25].
Barber's Paradox
The Barber's Paradox is attributed to Bertrand Russell:
"Suppose there is a town with one barber (who is a man); and that every man in the town keeps himself clean-shaven:
some by shaving themselves, some by attending the barber. It seems reasonable to imagine that the barber
obeys the following rule: He shaves all and only those men who do not shave themselves.
In fact, this is impossible: Does the barber shave himself?
If the barber does not shave himself, he must abide by the rule and shave himself.
If he does shave himself, according to the rule he will not shave himself."
Turing machine
"In Turing's original formulation, the workspace was imagined to be a scanner that looked at just one square
of a paper tape at a time, to see if a zero or one were written on it. Depending on what it 'saw,' it either
erased the zero or one and printed the other symbol, or left the square unchanged. It then moved the tape left
or right one square and looked again, in each case being governed by a finite set of hard-wired instructions
that formed its machine table. The tape was the memory." (Dennett p. 212) Infinite tape, printed with slashes
and blanks.
Instructions of the form:
(current_state, current_symbol, new_state, new_symbol, left/right)
Von Neumann turned Turing's specification into practical machine architecture. Turing machines can implement
all fully formalized processes (and therefore, rational thought). All digital computers direct descendants
of this design.
". . . Turing had proven - and this is probably his greatest contribution - that his Universal Turing
machine can compute any function that any computer, with any architecture, can compute. In effect, the
Universal Turing machine is the perfect mathematical chameleon, capable of imitating any other computing
machine and doing, during that period of imitation, exactly what that machine does." (Dennett p. 215)
Concept of virtual machine.
Turing test: human unable to distinguish the responses of a machine. ". . . we call programs intelligent if they
exhibit behaviors that would be regarded as intelligent if they were exhibited by human beings." (Simon & Kaplan)
"Hugh Loebner, the American businessman behind the annual prize, says it's still a good measure of machine intelligence.
The ultimate Loebner prize, he explains, is a gold medal and $100,000, which will go to the chatbot that passes the
Turing Test. The contest is held every year and the program that seems most human (ie. the one that comes third, after
the two human "confederates") wins the bronze medal and $2,000."
"The prospect that intrigued Newell came from Oliver Selfridge, who was using digital computers
to simulate a neural net-like model for pattern recognition which he dubbed 'Pandemonium.' Such a model organizes a number of
specialized agents (demons) into layers, with those in each layer competing in parallel to recognize a pattern. . .
Selfridge's work led Newell to the notion of a complex process being achieved through the interaction of simpler
subprocesses" [Bechtel, Abrahamsen, & Graham p. 11].
Introspectionism
Wilhelm Wundt
founded the first laboratory for psychological research in 1879. "The science of experience he envisaged was
supposed to be like chemistry: introspected experiential data were to be analyzed; the basic constituents
of conscious experience thus identified; and the patterns and laws by which these basic constituents combine
to constitute more complex conscious experiences (e.g., emotions) described." But Helmholtz and Freud argued
that unconscious inference influences behavior and thought, and are not available to introspection.
Tinklepaugh studied "delayed response." "An animal would be shown where either lettuce or a banana was hidden
and then, after a delay, be allowed to choose among several response sites (including the correct one). If the
chimpanzee found the reward, it was allowed to eat it. " If lettuce or bananas were used as expected, chimpanzees
completed the test without problem. If a banana was the bait and lettuce the reward, the chimpanzee would look
around for the banana. "The chimpanzees were learning and remembering not just what to do but also what the reward was."
Activity-Dependent Self-Organization
If kittens wear an eye-patch after birth, the "visual cortex neurons reorganize so as to become responsive almost
exclusively to input from the open eye." [Rose p. 143] Activity-dependent self-organization means that certain
synapses become strengthened and others pruned back on the basis of experience. Interplay of learning and memory.
Pavlov discovered dogs would salivate at the sound of the bell, what he called a conditioned reflex.
Gestalt Grouping Principles
Proximity. Things that are located close together are likely to be grouped as being
part of the same object.
Similarity. When objects are equally spaced, the ones that appear similar
tend to be grouped as being related.
Symmetry. Because random unrelated objects in the world are not expected to
exhibit symmetry, it would be most improbable for unrelated objects to exhibit symmetric relationships.
Good continuation. If objects are collinear, or arranged in such a way that it appears
likely that they continue each other, they tend to be grouped perceptually.
Common fate dictates that objects that move together are likely to be connected.
John Chowning demonstrated that frequencies group into separate sound sources if they are varied together (common fate).
Howard Gardner's five features of Cognitive Science:
In 1976 the Sloan Foundation established a "Particular Program" in Cognitive Science,
infusing a large amount of money to give a boost to the field. In the State of the Art Report
prepared in 1978, the authors claimed that "what has brought the field into existence is a common
research objective: to discover the representational and computational capacities of the mind and
their structural and functional representation in the brain." The cover of the report shows major
links between the subfields of Cognitive Science.
"Here is the central hypothesis of cognitive science: Thinking can best be understood in terms of
representational structures in the mind and computational procedures that operate on those
structures" [Thagard p. 10].
Philosophy
Descartes held in 1641 "that the mind was a metaphysical entity that interacted with the material
body and that thinking was a property of the mind, not the body."
Dualism: mind and brain are separate things. "A person therefore lives through two collateral
histories, one consisting of what happens in and to his body, the other consisting of what
happens in and to his mind. The first is public, the second private. The events in the first
history are events in the physical world, those in the second are events in the mental world."
Hobbes (1656) held the contrary view, that thinking was a material process and could in principle
be performed by a machine.
Descartes's position, that the mind and body are two entities of different substance, is
called dualism. The most celebrated modern attack on dualism was published in 1949 by
Gilbert Ryle, in which he identifies dualism as a category mistake.
"Such in outline is the official theory. I shall often speak of it, with deliberate abusiveness,
as 'the dogma of the Ghost in the Machine'. I hope to prove that it is entirely false, and false
not in detail but in principle. It is not merely an assemblage of particular mistakes. It is one
big mistake and a mistake of a special kind. It is, namely, a category-mistake." [Ryle p. 26]
If there is a separation between physical and mental, how is there communication between the two? A
category mistake is trying to compare two things that belong to different categories: Where is NYU?
"What this reflects, on Ryle's view, is the category mistake of assimilating behavioral concepts
to notions about mentality, the mistaken supposition that there must be a 'ghost in the machine,' an
intelligent inner pilot guiding the complex movements of the human body. But this Ryle argued, is
like meeting Uncle Joe and Grandma and Mom while wondering where the family really is. Resolution
of our conceptual difficulties in this regard, he supposed, lies not in the reduction of mental
predicates to material ones, but rather a simple recognition that statements about perception,
memory, belief, and other mental states are nothing more significant than a series of short-hand
ways of describing human behavior of identifiable sorts. Cartesian dualism is an elaborate myth."
[www.philosophypages.com]
Serial Order
The Hixon Symposium met at Cal Tech in September of 1948. Karl Lashley presented "The Problem of Serial
Order in Behavior" in which he pointed out that sequences of stimulus and response could not possibly account
for the complexity of behavior. Typing errors, speaking errors. "The organization is best thought of as
hierarchical: there are the broadest overall plans, within which increasingly fine-grained sequences of
actions are orchestrated." [Gardner p. 13]
Lashley: "Attempts to express cerebral function in terms of the concepts of the reflex arc, or of associated
chains of neurons, seem to me doomed to failure because they start with the assumption of a static nervous
system. Every bit of evidence available indicated a dynamic, constantly active system, or, rather, a composite
of many interacting systems."
Searle's Chinese Room. "This thought experiment is supposed to prove the impossibility of what Searle
calls 'strong AI,' the thesis that 'the appropriately programmed digital computer with the right inputs and
outputs would thereby have a mind in exactly the sense that human beings have minds.'" Systems Reply: that the CR does understand Chinese.
Shannon and information theory
"information can be thought of in a way entirely divorced from specific content or subject matter as simply
a single decision between two equally plausible alternatives." Communication system consists of an information
source, which "selects a desired message out of a set of possible messages. . . The transmitter changes this
message into the signal which is actually sent over the communication channel from the transmitter to the
receiver . . . the receiver is a sort of inverse transmitter, changing the transmitted signal back into a
message, and handing this message on to the destination." (Weaver p. 7) Changes in the transmitted signal are called noise.
Information is a measure of one's freedom of choice when one selects a message. (Weaver p. 9) Not to be confused
with meaning. If one has two choices, the information associated with this situation is unity (arbitrary designation).
The amount of information is defined to be measured by the logarithm of the number of available choices. 21 = 2 ,
or 1 bit of information. 22 = 4, or 2 bits. Second law of thermodynamics: entropy always increases. Information
equivalent to entropy, situation with low information has low entropy. "The ratio of the actual to the maximum entropy
is called the relative entropy of the source. If the relative entropy of a certain source is, say .8, this roughly
means that this source is, in its choice of symbols to form a message, about 80 per cent as free as it could possibly
be with these same symbols. One minus the relative entropy is called the redundancy." Weaver p. 13 The redundancy of English is roughly 50%.
Materialism: "there is only one sort of stuff, namely matter - the physical stuff of physics, chemistry,
and physiology - and the mind is somehow nothing but a physical phenomenon." [Dennett p. 33]
Functionalism: "if you reproduced the entire 'functional structure' of the human wine taster's
cognitive system (including memory, goals, innate aversions, etc.), you would thereby reproduce all the
mental properties as well, including the enjoyment, the delight, the savoring that makes wine-drinking something
many of us appreciate." [Dennett p. 31]
Brain in the Vat
Would it be possible for evil scientists to float our brain in a vat and make us think that we were interacting with a real world?
"But what am I, now that I suppose that there is a certain genius which is extremely powerful, and, if I may say so,
malicious, who employs all his powers in deceiving me? Can I affirm that I possess the least of all those things which
I have just said pertain to the nature of the body? I pause to consider, I revolve all these things in my mind, and I
find none of which I can say that it pertains to me." [Descartes]
Virtual reality is difficult because there is no way to generate all plausible responses to free user actions and no
way to store all plausible responses. Virtual reality therefore enforces either a restricted range of action or
passivity on the part of the user, as do hallucinations.
Hallucinations can be generated, Dennett suggests, when the brain supplies more or less random answers to purposive questions.