1. Categorization and Hypothesis Testing
Four attributes:
(1) Number of shapes (1, 2, 3)
(2) Number of borders (1, 2, 3)
(3) Kind of shape (rectangle, circle, cross)
(4) Colors of shapes (black, red, green)
How do people test hypotheses in a non-scientific context in order to form concepts?
Bruner, Goodnow, & Austin (1956) conducted the following experiment on concept formation:
The task of the participant was to find out about which attributes on a card constituted a category.
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2. Categorization and Hypothesis Testing
How do people test hypotheses in a non-scientific context in order to form concepts?
Bruner, Goodnow, & Austin (1956) conducted the following experiment on concept formation:
The task of the participant was to find out about which attributes on a card constituted a category.
In so-called selection experiments, the participants chose one card, and the experimenter gave feedback as to whether the card belonged to the category or not.
In so-called reception experiments, the participants got one card per trial and had to indicate whether the card belonged to the category or not. The experimenter provided feedback about the correctness of the answer.
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3. Categorization and Hypothesis Testing
Bruner et al. (1956) found the following four strategies their participants used:
Simultaneous Scanning
Successive Scanning
Conservative Focusing
Focus Gambling
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4. Simultaneous Scanning
The participants consider all attributes at once.
Simultaneous Scanning is a very conservative strategy; the category of a participant never contains attributes that do not belong to the target category (except for disjunctive categories).
„Three green crosses with two borders“
„Green crosses “ (Number of shapes and borders irrelevant)
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5. Successive Scanning
The participants considers only one attribute at a time.
The participant has a hypothesis about one attribute, such as „red“ for color. She or he draws red cards until a red card gets negative feedback.
She or he now goes over to another attribute, such as „two borders“, and draws cards until this hypothesis turns out to be false. The advantage of this strategy is that it is not demanding for memory. The disadvantage is that it is inefficient.
Moreover, the participant cannot use information from prior draws, unless the cards drawn from the deck are open or memory is perfect.
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6. Conservative Focusing
The participants change just one attribute on each trial.
In this example, the participant changes only the color. Is the feedback „no“, the participant can assume that the attribute color is not part of the category.
(cf. John Platt on testing scientific hypotheses)
(Former stimulus;
belongs to the category)
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7. Focus Gambling
The participant changes all except one attribute on each trial.
In this example, the participant changes all except the color. The advantage of this strategy lies in the fact that if the feedback is „yes“, the category color is probably „red“. However, the probability of an affirmative feedback is relatively low.
(cf. Karl Popper on the strategy of testing scientific hypotheses).
(Former stimulus;
belongs to the category)
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8. Positive Test Strategy
Bruner, Goodnow, & Austin (1956, p. 86) concluded from their studies:
“Human subjects — and the same may be true of other species as well — prefer a direct test of any hypothesis they may be working on. [Suppose that] a subject is faced with deciding whether a white door or a black door is the correct entrance to a reward chamber and adopts the hypothesis that the white door is correct. There are two ways of testing this hypothesis. The direct way is to try the white door. The indirect way is to try the black door.”
This is an example of a positive test strategy.
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