Congruence bias
Encyclopedia
Congruence bias is a type of cognitive bias
similar to confirmation bias
. Congruence bias occurs due to people's overreliance on direct testing of a given hypothesis
, and a neglect of indirect testing.
, a subject is presented with two buttons, and is told that pressing one of those buttons, but not the other, will open a door. The subject adopts the hypothesis that the button on the left opens the door in question. A direct test of this hypothesis would be pressing the button on the left; an indirect test would be pressing the button on the right. The latter is still a valid test because once the result of the door's remaining closed is found, the left button is proven to be the desired button. (This example is parallel to Bruner, Goodnow, and Austin's example in the psychology classic A Study of Thinking.)
We can take this idea of direct and indirect testing and apply it to more complicated experiments in order to explain the presence of a congruence bias in people. In an experiment, a subject will test his own usually naive hypothesis again and again instead of trying to disprove it.
The classic example of subjects' congruence bias is found in Wason (1960, 1968b). Here, the experimenter gave subjects the number sequence "2, 4, 6," telling the subjects that this sequence followed a particular rule and instructing subjects to find the rule underlying the sequence logic. Subjects provided their own number sequences as tests to see if they could ascertain the rule dictating which numbers could be included in the sequence and which could not. Most subjects respond to the task by quickly deciding that the underlying rule is "numbers ascending by 2," and provide as tests only sequences concordant with this rule, such as "3, 5, 7," or even "pi plus 2, plus 4, plus 6." Each of these sequences follows the underlying rule the experimenter is thinking of, though "numbers ascending by 2" is not the actual criterion being used. However, because subjects succeed at repeatedly testing the same singular principle, they naively believe their chosen hypothesis is correct. When a subject offers up to the experimenter the hypothesis "numbers ascending by 2" only to be told he is wrong, much confusion usually ensues. At this point, many subjects attempt to change the wording of the rule without changing its meaning, and even those who switch to indirect testing have trouble letting go of the "+ 2" convention, producing potential rules as idiosyncratic as "the first two numbers in the sequence are random, and the third number is the second number plus two." Many subjects never realize that the actual rule the experimenter was using was simply just to list ascending numbers, because of the subjects' inability to consider indirect tests of their hypotheses.
Wason attributed this failure of subjects to an inability to consider alternative hypotheses, which is the root of the congruence bias. Jonathan Baron
explains that subjects could be said to be using a "congruence heuristic," wherein a hypothesis is tested only by thinking of results that would be found if that hypothesis is true. This heuristic, which many people seem to use, ignores alternative hypotheses.
To avoid falling into the trap of the congruence bias, Baron suggests that the following two heuristics be used:
Cognitive bias
A cognitive bias is a pattern of deviation in judgment that occurs in particular situations. Implicit in the concept of a "pattern of deviation" is a standard of comparison; this may be the judgment of people outside those particular situations, or may be a set of independently verifiable...
similar to confirmation bias
Confirmation bias
Confirmation bias is a tendency for people to favor information that confirms their preconceptions or hypotheses regardless of whether the information is true.David Perkins, a geneticist, coined the term "myside bias" referring to a preference for "my" side of an issue...
. Congruence bias occurs due to people's overreliance on direct testing of a given hypothesis
Hypothesis
A hypothesis is a proposed explanation for a phenomenon. The term derives from the Greek, ὑποτιθέναι – hypotithenai meaning "to put under" or "to suppose". For a hypothesis to be put forward as a scientific hypothesis, the scientific method requires that one can test it...
, and a neglect of indirect testing.
Examples
Suppose that in an experimentExperiment
An experiment is a methodical procedure carried out with the goal of verifying, falsifying, or establishing the validity of a hypothesis. Experiments vary greatly in their goal and scale, but always rely on repeatable procedure and logical analysis of the results...
, a subject is presented with two buttons, and is told that pressing one of those buttons, but not the other, will open a door. The subject adopts the hypothesis that the button on the left opens the door in question. A direct test of this hypothesis would be pressing the button on the left; an indirect test would be pressing the button on the right. The latter is still a valid test because once the result of the door's remaining closed is found, the left button is proven to be the desired button. (This example is parallel to Bruner, Goodnow, and Austin's example in the psychology classic A Study of Thinking.)
We can take this idea of direct and indirect testing and apply it to more complicated experiments in order to explain the presence of a congruence bias in people. In an experiment, a subject will test his own usually naive hypothesis again and again instead of trying to disprove it.
The classic example of subjects' congruence bias is found in Wason (1960, 1968b). Here, the experimenter gave subjects the number sequence "2, 4, 6," telling the subjects that this sequence followed a particular rule and instructing subjects to find the rule underlying the sequence logic. Subjects provided their own number sequences as tests to see if they could ascertain the rule dictating which numbers could be included in the sequence and which could not. Most subjects respond to the task by quickly deciding that the underlying rule is "numbers ascending by 2," and provide as tests only sequences concordant with this rule, such as "3, 5, 7," or even "pi plus 2, plus 4, plus 6." Each of these sequences follows the underlying rule the experimenter is thinking of, though "numbers ascending by 2" is not the actual criterion being used. However, because subjects succeed at repeatedly testing the same singular principle, they naively believe their chosen hypothesis is correct. When a subject offers up to the experimenter the hypothesis "numbers ascending by 2" only to be told he is wrong, much confusion usually ensues. At this point, many subjects attempt to change the wording of the rule without changing its meaning, and even those who switch to indirect testing have trouble letting go of the "+ 2" convention, producing potential rules as idiosyncratic as "the first two numbers in the sequence are random, and the third number is the second number plus two." Many subjects never realize that the actual rule the experimenter was using was simply just to list ascending numbers, because of the subjects' inability to consider indirect tests of their hypotheses.
Wason attributed this failure of subjects to an inability to consider alternative hypotheses, which is the root of the congruence bias. Jonathan Baron
Jonathan Baron
Jonathan Baron is a Professor of Psychology at the University of Pennsylvania in the science of decision-making.-Life and career:Baron was born in Boston, Massachusetts, in 1944, and received a B.A. from Harvard in 1966 and a Ph.D. from Michigan in 1970, both in psychology...
explains that subjects could be said to be using a "congruence heuristic," wherein a hypothesis is tested only by thinking of results that would be found if that hypothesis is true. This heuristic, which many people seem to use, ignores alternative hypotheses.
To avoid falling into the trap of the congruence bias, Baron suggests that the following two heuristics be used:
- Ask "How likely is a yes answer, if I assume that my hypothesis is false?" Remember to choose a test that has a high probability of giving some answer if the hypothesis is true, and a low probability if it is false.
- "Try to think of alternative hypotheses; then choose a test most likely to distinguish them — a test that will probably give different results depending on which is true." An example of the need for the heuristic could be seen in a doctor attempting to diagnose appendicitis. In that situation, assessing a white blood cell count would not assist in diagnosis, because an elevated white blood cell count is associated with a number of maladies.