It just so happens that the Wason card task was a central part of my own PhD research.
The problem here is that your secondary sources do not understand the difference between confirmation and verification. For Wason, the issue was verification. To verify a hypothesis, one must demonstrate definitively that it is true. To confirm it, one must merely present evidence that is consistent with it. Verification requires certainty. Confirmation does not. (There is a whole history about logical-positivism's shift from verfication to confirmation, Popper's countervailing falsificationism, and Wason's position in the history of philosophy of science behind this, that you probably don't want to know about.) In order to *verify* the vowel-even rule, you must pick up the E and the 7. Picking up the E alone might confirm the rule (or falsify it), but it cannot verify it. The 4 is, of course, irrelevant. Verification is only possible in extremely constrained situations, however (i.e., it is not a very realistic model of knowledge-gathering) so, over the decades, verification got softened to confirmation, and the whole confirmation-bias industry got started (around the time of Tversky & Kahneman's "classic" work). Wason and his student, Johnson-Laird, are often "read into" that history by later textbook writers (and not without some justification, but it is not a simple matter). Hope this helps, Chris --- Christopher D. Green Department of Psychology York University Toronto, ON M3J 1P3 Canada [email protected] http://www.yorku.ca/christo/ ========================= On 2012-11-06, at 11:41 AM, Julie Osland wrote: > > > > Dear tipsters > > > I need help with the confirmation bias and how the responses of the majority > of students faced with the original Wason Card Selection Task illustrate that > bias. > > > The example in the book is: > > Suppose that each of the cards below has a number on one side and a letter on > the other, and someone tells you: “If a card has a vowel on one side, then it > has an even number on the other side.” Which one(s) of the cards would you > need to turn over to decide whether the person is lying? E K 4 7 > > To be clear, I totally understand what the confirmation bias is [tendency to > search for and interpret information in ways that supports one’s existing > beliefs or expectations] and what the correct answer to the Wason Card Task > is, and why [E and 7—modus ponens and modus tollens, respectively]. > > According to secondary sources [a gen psych and a social psych text], Wason > and Johnson-Laird (1972) found the two most comment responses to be turning > over both cards E and 4, and turning over just card E. These secondary > sources say that these responses [E and 4, and just E] illustrate the > confirmation bias without explaining how these responses illustrate the bias. > Turning over the card E could result in finding a 4 –an outcome that would > confirm the rule, but it could result in finding a 7 if the rule is false. > Because this option could potentially confirm or disconfirm the rule I don’t > see this choice as a definite confirmation strategy. I can see how choosing > 4 would potentially confirm the rule, even though affirming the consequent is > not a valid argument. Turning over the 4 and finding an E would confirm the > hypothesis. Am I missing something obvious regarding as two how both the E > only and E and 4 combination are a clear example of the confirmation bias? > Please help. > > > > > > > -- > Dr. Julie A. Osland, M.A., Ph.D. > Assistant Professor of Psychology > Wheeling Jesuit University > 316 Washington Avenue > Wheeling, WV 26003 > > Office: (304) 243-2329 > e-mail: [email protected] > --- > > You are currently subscribed to tips as: [email protected]. > > To unsubscribe click here: > http://fsulist.frostburg.edu/u?id=430248.781165b5ef80a3cd2b14721caf62bd92&n=T&l=tips&o=21533 > > (It may be necessary to cut and paste the above URL if the line is broken) > > or send a blank email to > leave-21533-430248.781165b5ef80a3cd2b14721caf62b...@fsulist.frostburg.edu > > > --- You are currently subscribed to tips as: [email protected]. To unsubscribe click here: http://fsulist.frostburg.edu/u?id=13090.68da6e6e5325aa33287ff385b70df5d5&n=T&l=tips&o=21537 or send a blank email to leave-21537-13090.68da6e6e5325aa33287ff385b70df...@fsulist.frostburg.edu
