A few days ago, the New York Times posted a piece which argued that confirmation bias is a common failure of human thinking. Confirmation bias is the idea that one tends to interpret new facts in terms of one's existing preconceptions.
The author of the study, David Leonhardt, discusses confirmation bias by way of a mathematical example where the reader is asked to guess the rule determining the sequence "2, 4, 8" by testing additional examples. Thus, one can type in sequences like "4, 8, 16" or "10, 95, 387" and see if they follow the same rule as the sequence "2, 4, 8." If one enters a sequence like "4, 8, 16" into the boxes in Leonhardt's article, one receives a confirmation that it also follows the same rule as that which produced "2, 4, 8."
So, just what is this rule? Leonhardt states:
"...most people start off with the incorrect assumption that if we’re asking them to solve a problem, it must be a somewhat tricky problem. They come up with a theory for what the answer is, like: Each number is double the previous number."
The true rule, Leonhardt explains, is not that each number is double the previous number, but rather that each subsequent value is greater than the preceding value. That people assume the former rule is taken as evidence for confirmation bias. As stated, "Not only are people more likely to believe information that fits their pre-existing beliefs, but they’re also more likely to go looking for such information."
However, it strikes me that there are other, rather sensible reasons that people will assume the former rule that Leonhardt does not consider. One is found among the the well-known maxims of conversation, created by the famous philosopher of language, Paul Grice. These maxims, well-known to any introductory linguistics student, state that conversation is guided by constraints of quantity, quality, relation, and manner. As a default, we assume that speakers will give only enough information, be truthful with it, be relevant to the topic, and be clear, respectively. When speakers deviate from these expectations, we are annoyed with the conversation. In such cases, we might state "He was long-winded." or "He kept going off on tangents." Our ability to follow these maxims demonstrates our cooperation within a conversation. Hence, they fall under what Grice terms the cooperative principle.
Grice's maxim of quantity states that one should not make his/her contribution more informative than required. Thus, when someone asks for directions to a particular room in a building, one does not expect the speaker to provide instructions on how to open a door nor the history of certain rooms that the listener will likely pass. If additional details are provided, our interpretation is that they must somehow be relevant (incidentally, another maxim). So, just what might Grice have to do with Leonhardt's example here?
Consider the initial example that he provides: 2, 4, 8. The reader's expectation from this example is that it is as informative as necessary. If the author chose a sequence where each subsequent value is double the previous value, then this must be relevant to the question. After all, the expectation is that the author has provided this information and it must be important. When we hear that the rule is, "Haha!", not what we assumed, our reaction is one of surprise. Why provide this particular example if any random sequence, like 1, 5/3, 9, would have sufficed?
Providing too much information in this way would seem to be a case of conversational deception. The listeners/readers are led astray believing that the author was following the maxim of quantity and relevance when, in fact, the example was intended to be overly informative. So, are 78% of those who participate in this particular task guilty of confirmation bias? Perhaps some are, but Leonhardt would be wise to consider that most people are guided not by the expectation that the problem is tricky, but rather by the expectation that the author's example does not provide too much information. An entirely different outcome would be produced if the example were as simple as "1, 2, 3."
*Incidentally, the rule "Each number is double the previous number." is just a more specific case of the rule "Each number is greater than the previous number." The first entails the second.