Experimental research on instrumental conditioning begins with Thorndike’s classic “puzzle box” experiments.
(1848-1894) n n
Influenced by Darwin’s theory of evolution: q
Evolution toward intelligent, problemsolving abilities may have begun early q
Consequently, such abilities should be apparent in animals other than us humans
Wrote Animal Intelligence (1882) q
Used anecdotal evidence to support the view that animals are capable of reasoning and problem -solving, such as dogs or cats learning to operate a door-latch to let themselves out.
n Anecdotal evidence not reliable n Nobody had actually observed the animals learning to operate a latch mechanism –
Romanes simply assumed that it had taken reasoning to solve the problem.
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n Only an experiment can show how animals actually go about solving problems such as the operation of a door-latch.
n Consequently, he built several “puzzle boxes,” made from old fruit crates, equipping each with different types of latch-mechanism.
n Dogs or cats would be placed inside the box and observed as they went about learning how to operate the latch.
Although crudely made, boxes like this one served their purpose.
Note the door at front center, complete with a latch that can be operated from inside.
Box A
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Place a bit of fish in a bowl outside of the puzzlebox.
Place a cat inside the box and latch the door behind it.
Start your stopwatch.
Observe what the cat does.
When the cat emerges from the box, stop the stopwatch, record the data, and let the cat eat a bit of the fish.
Repeat for trial 2, 3, and so on, until the cat is rapidly escaping from the box.
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This shows results for four cats in the same box previously pictured.
The gaps labeled with number days represent tests of retention.
“Of several responses made to the same situation, those which are accompanied or closely followed by satisfaction to the animal will, other things being equal, be more firmly connected with the situation, so that, when it recurs, they will be more likely to recur; those which are accompanied or closely followed by discomfort to the animal will, other things being equal, have their connections with that situation weakened, so that, when it recurs, they will be less likely to occur. The greater the satisfaction or discomfort, the greater the strengthening or weakening of the bond . “
Thorndike (1914)
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A “situation” is all those stimuli, both external and internal, that identify a given circumstance (in
Thorndike’s experiment, being hungry and confined in a puzzle box).
The situation elicits a variety of behaviors by virtue of associative connections between stimulus and response (some innate, some learned).
When a given response is accompanied or followed by “satisfaction,” its S-R connection to the situation is strengthened, thus increasing the probability of that behavior in that situation (positive law of effect).
Discomfort has the opposite effect, weakening the
S-R bond and thus decreasing the probability of the behavior (negative law of effect).
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n n n
Variation – A given “situation” elicits a certain population of behavioral acts, some of which occur with higher or lower probability than others.
Selection – Satisfiers and discomforters play the role of selection, determining which behaviors will be favored or disfavored.
Like Begets Like – Those behavioral acts selected occur more often in the population in succeeding trials (differential survival).
n Critics chastised Thorndike for using mentalistic terms like “satisfaction” and
“discomfort.” How could Thorndike know what was going on in the animal’s mind?
n However, Thorndike was ahead of his critics, as he had been careful to provide operational definitions in terms of objective behavior, as shown on the next slide.
By a satisfying state of affairs is meant one which the animal does nothing to avoid, often doing such things as attain and preserve it. By a discomforting or annoying state of affairs is meant one which the animal commonly avoids and abandons.
The satisfying and annoying are not synonymous with favorable and unfavorable to the life of either the individual or the species. Many animals are satisfied by deleterious conditions. Excitement, overeating, and alcoholic intoxication are, for instance, three very common and very potent satisfiers of man. Conditions useful to the life of the species in moderation are often satisfying far beyond their useful point: many conditions of great utility to the life of the species do n ot satisfy and may even annoy its members .
Thorndike (1914)
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