Confirmation Bias

Confirmation bias involves the tendency – usually, but not necessarily, unconscious – for individuals to look for and accept information that confirms what they already know and believe.

In other words, it involves a cognitive tendency to place greater importance on “evidence” that generally supports a position we already hold.

This process has been famously simulated by Wason and Johnson-Laird’s (1972) “Four Card” puzzle, the objective of which is to solve an apparently simple “If X, Then Y” statement using just the aforementioned 4 cards.

The significance in relation to confirmation bias, as will hopefully be demonstrated if you run the sim in your classroom, is that the majority of your students will choose a solution that confirms what they already know, rather than testing that knowledge, as the puzzle requires.

The beauty of the sim is its apparent simplicity.

Students only have 4 cards from which to choose and the number of potential combinations is very small (reduced even further if they immediately realise they must initially choose a vowel).

In all probability, most students will choose A and 4, but a reasonable number should work-out the correct solution.

Sim Suggestion

Familiarise yourself with the PowerPoint Presentation version you plan to use.

1. Show the class the “Wason Card Problem” slide.

• If you only intend to show your students the correct answer you can use the manual Presentation version. In this version you can explain (or ask those who got it right to explain) the solution.

• If you want to take your students through the incorrect / correct answers to the problem, use the worked Presentation version.

2. Working individually, give your students a few minutes (5 minutes or less is probably enough time) to decide their solution to the statement (“If a card has a vowel on one side, it has an even number on the other”).

3. When the time’s up, ask all your students to stand-up, then sit down if, in turn, their answer consisted of choosing:

• A single card: it doesn’t matter which card. Selecting one card can only confirm what you already know.
• A and D
• 4 and 7
• D and 4
• D and 7
• A and 4

You can, if you want, explain why each of these combinations (if any students have chosen them) merely confirms the statement (“confirmation bias”).

At this point the only students left standing will have chosen the correct solution (A + 7).

This is likely to be a minority of the students in the class.

4. Explain (or ask those who got it right to explain) the solution.

While the sim is interesting in its own right (and if you teach both psychology and sociology classes it might be interesting to see what proportion of students in each class arrived at the correct solution. You could hypothesise that psychology students, because they are required to use mathematics more in their studies, are more-likely to arrive at the correct solution than sociology students).

In addition (or alternatively), you can introduce the simulation into areas like:

• The media: what are the implications of confirmation bias for the claim people actively seek-out information that confirms, rather than questions, their beliefs?

• Research methodology: what implications might confirmation bias have for research reliability?

• Science: how does confirmation bias show the importance of falsification in social / psychological research?

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