Our brains are subject to cognitive biases that distort how we actually think. This includes how we ask questions, make observations, and gather information. Each of these is impacted by common experiences like what information we encounter first or what we presume is a correct answer.

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If we’re not checking our confirmation biases, our brains will implicitly make connections to support our suspicions or assumptions.

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The activity in this mini unit builds on Peter Cathcart Wason’s (1960) 2-4-6 Hypothesis Rule Discovery task. After you complete it, you will have the opportunity to compare results with your lab.

The original 2-4-6 Hypothesis Rule Discovery Task was created by Peter Cathcart Wason, a cognitive psychologist at University College, London. Noticing that the belief that humans reasoned by logical analysis failed to hold true, he sought to explain inconsistencies in reasoning.

In 1960, Wason conducted an experiment with 29 psychology undergraduates (17 men and 12 women). Most participants in the study tended to fall into a narrow hypothetical “trap”— in the original study, the first example was “2, 4, 6” and students formed a mental hypothesis like “even numbers ascending by 2” and then proceeded to propose examples that adhered to the hypothesis.

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As you probably figured out, in order to distinguish between a specific hypothesis like "even numbers ascending by 2" against other rules consistent with a "2, 4, 6" prompt, you needed to propose some examples that would NOT match candidate hypotheses. For example, trying a set of numbers such as "2, 6, 10" to test the “ascending by 2” portion of the hypothesis or inputting "1, 3, 5" to check the "even numbers" clause.

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To describe this tendency for humans to generate, and seek out, information that confirms their hypotheses, Wason coined the term “confirmation bias.” It has been studied (and confirmed!) in a variety of different populations and settings ever since.

When we typically hear about avoiding bias, we might think about ways of being a good person. Mitigating confirmation bias (CB), though, isn’t about personality, temperament, or tolerance. Instead, confirmation bias is a cognitive bias that fools us by selectively filtering data and distorting analyses to support favored beliefs or hypotheses.

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We’re all vulnerable to biases even on the level of our senses simply based on expectations and the physical realities of our visual processing. For instance, despite knowing that the two center circles shown below are the same size, one will always appear larger because of the way our brains make sense of the size difference of the bordering circles.

The next image below is not a video or gif. Nonetheless, the orientation of the circles tricks our brains into thinking we’re registering movement:

Confirmation bias is the tendency of people’s minds to seek out information that supports the views they already hold, and it is just as difficult to “unsee” or “reframe” as these visual tricks. Sometimes these initial views can result just from receiving some information first or from a trusted source. This is further compounded by the tendency to interpret later evidence in ways that support their pre-existing beliefs, expectations, or hypotheses.

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For instance: is this pig a darling or a monster? 

In the absence of any other information, it can be hard to tell. What’s more difficult to confirm, according to a 2014 study, is which pigs are actually aggressive and which are not. “Actually” being the operative word: the students in question viewed the exact same footage of pigs nosing around and playing, just with the images mirrored and accompanied by different labels. 

Despite watching the same video, study participants who viewed what they thought were pro-social pigs reported more positive interactions and fewer negative interactions, compared with those who viewed the “other” pigs. It turns out, when someone in a lab coat frontloads a belief that one recording you watch is of cuties and the second is of baddies, you’ll probably, totally, fully see baddies being bad and vice versa.

What does this mean? Are we so easily misled by labels? Well no, a whole body of literature on confirmation bias shows that our brains reorient our observations and experiences to fit the narratives already in our minds. Worse, once we hold a belief, it is easier for us to pay attention to and accept  new information that is consistent with those beliefs. More upsetting still, we’re suddenly skeptical of information that contradicts these beliefs.

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Another classic example that led to profound changes in scientific methods, which also improved reducing confirmation bias, is the late 1800s/early 1900s case of the horse Clever Hans. Paraded around and reported in The New York Times (1904) as a mathematical wonder, even his owner believed he was more than just a trick pony: he really believed that his horse could do basic arithmetic. 

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In 1907, however, Psychologist Oskar Pfungst demonstrated Hans was not performing these mental tasks because he understood math. Instead, good boy Hans was dutifully watching the reactions of his trainer and responding directly to involuntary cues in the trainer’s body language. His trainer was unaware that he was even signaling these cues. The Clever Hans effect continues to be important knowledge in the observer-expectancy effect and various studies in animal behavior and cognition.

When unchecked, CB is a major block to research and new discoveries. The last thing we want is to assume we’re right because we’ve read the evidence in our own favor. Similarly, we want to avoid being sloppy when justifying our successes. Citing the wrong reasons for the right answers is also a stumbling block to good science.

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Scientific research strives for the unbiased interpretation of experimental results, but confirmation bias distorts how we:

• Frame and ask questions.some text
  • Ex: Promoting inaccurate theories because flawed experiments won’t effectively test hypotheses and others may use these flawed results.
• Seek out information.some text
  • Ex: Undermining attempts to mitigate subjectivity, making it difficult to draw accurate conclusions.
• Collect observations.some text
  • Ex: Skewing perceptions of reality, leading scientists to favor evidence supporting their theories and disregard contradictory evidence.
• Make sense of data.some text
  • Ex: Impairing decision-making and rooting choices on compromised information.
  • Ex: Compromising peer review, potentially leading to research misconduct.

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Sometimes, the best way to mitigate CB is to try an experiment on yourself that can both prove and disprove your own hypothesis. Like the Wason exercise, self-checks in our research process encourage critical evaluation of data and help us maintain an open and transparent research atmosphere.

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Reflection/Discussion Question(s):

How might you design experiments that falsify your hypotheses? What other steps can you take right now to mitigate confirmation bias in your research?

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1. Confirmation Bias is one of many naturally-occurring cognitive biases that influence our thinking and observations.

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2. We have a tendency to behave in ways that confirm our hypotheses. To counteract this tendency, we can intentionally seek out examples that counter our hypotheses.

F.A.M. Tuyttens, S. de Graaf, J.L.T. Heerkens, L. Jacobs, E. Nalon, S. Ott, L. Stadig, E. Van Laer, B. Ampe, “Observer bias in animal behaviour research: can we believe what we score, if we score what we believe?”, Animal Behaviour, Volume 90, 2014, Pages 273-280, ISSN 0003-3472, https://doi.org/10.1016/j.anbehav.2014.02.007. 

Grobman, K. H. (2003). Confirmation Bias: A class activity adapted from Wason’s 2-4-6 Hypothesis Rule Discovery Task.Retrieved from:http://www.DevPsy.org/teaching/method/confirmation_bias.html