Anchoring bias

• What is cognitive bias?


  Cognitive bias is a systematic error in thinking that occurs when people are processing and interpreting information in the world around them and affects the decisions and judgements that they make.
• What are the three reasons for forming cognitive biases?


  Humans are cognitive misers, and do not have the time, recourses or desire to make a decision, so heuristics are used

  Ego depletion, a lack of self-control or willpower

  When cognitive load is too high
• How do biases link to dual systems theory?


  A heuristic is a part of system 1, and is a mental shortcut that allows individuals to solve problems and make judgements quickly and efficiently. They shorten decision-making time, but also lead to cognitive biases and errors. they may lead to inaccurate judgements about how commonly things occur and how representative certian things may be, contributing to stereotypes and prejudice. According to DST, when a decision is made, it either uses system 1 or system 2. (system 1 being impulsive, fast and emotional, and system 2 being rational, logical, and slow)
• What is the representativeness heuristic?


  One specific type of heuristic is the representativeness heuristic, which involves making a decision to the most representative mental prototype ( for example, if an old lady reminds you of your grandmother you assume that they share many characteristics)
• What is anchoring bias?


  Anchoring bias is the tendency to rely too heavily on the first piece of information offered (the 'anchor') when making decisions.
• What did Plassman (2008) do?


  Plassman et al (2008) showed the effect of anchoring on wine tasting- giving participants wine to sample while being in an fMRI. The wines were differentiated using retail prices. The prices served as an anchor, as the $90 bottle of wine was reported to be a better wine, and activated the medial orbitofrontal cortex, which is involved in experiencing pleasure.
• What was Tversky and Kahneman (1974)'s aim?


  To investigate anchoring bias with a mathematical problem
• What was Tversky and Kahneman (1974)'s procedure?


  A sample of high school students were randomly assigned to two conditions:

  The ascending condition were asked to estimate the value of 1x2x3x4x5x6x7x8 in five seconds

  The descending condition were asked to estimate the value of 8x7x6x5x4x3x2x1 in five seconds

  The researchers assumed that the ascending group would use 1 as an anchor, as you read from left to right, and therefore estimate a lower value than the descending group, who would have used 8 as an anchor.
• What were Tversky and Kahneman (1974)'s findings?


  The median for the ascending group was 512, the median for the descending group was 2250. The actual value is 40320.
• What was Tversky and Kahneman (1974)'s conclusion?


  The first piece of information is relied on to make decisions. The findings support anchoring bias as the participants relied on the first piece of information to make decisions. It also supports the DST by finding evidence for system 1 thinking-fast and impulsive
• What are some strengths of Tversky and Kahneman (1974)'s study?


  It is a simple experiment that is easily replicated, allowing reliability to be established

  Highly controlled so high internal validity

  Supports DST and anchoring bias
• What are some weaknesses of Tversky and Kahneman (1974)'s study?


  Low ecological validity as is artificial

  The median was used to report the data- may not be representative

  Participant variability may have altered results
• What was Englich and Mussweiler (2001)'s aim?


  To determine the effect of a prosecutors suggestion for sentencing on the decision-making of a judge
• What was Englich and Mussweiler (2001)'s procedure?


  Englich and Mussweiler were interested in finding if the request for a certian length of sentence could influence the decision made by a judge.

  They conducted a pilot study on 24 senior law students, collecting advice from highly experienced trial judges. The average reccomended prison term suggested was 17.21 months, which was then used as a basis for determining anchors.

  Using an independent samples design, the researchers used the same case study for both conditions: One being the low anchor and the other being the high anchor.

  The sample was 19 trial judges (15 male and 4 female) with an average age of 29.37 and average 9.34 months of experience.

  The participants were given a case of alleged rape, the prosecutor in one condition demanding 2 months, and in the other, demanding 34 months.

  The participants were given the case materials along with copies of the penal code, asked to read through them and form an opinion on the case. After 15 minutes, they were given a questionnaire, half of them told that the prosecutor demanded 2 months and the other 34.

  They were also asked:

  Do you think the sentence was too low, adequate, too high?

  What sentence would you recommend?

  how certian are you about your sentencing decision? (1-9)

  How realistic do you think this case is? (1-9)
• What were Englich and Mussweiler (2001)'s findings?


  The average rating for the realism of the case was 7.17. The judges certainty was on average 4.53. The low anchor condition had an average sentence of 18.78 months, and the high anchor condition had an average sentence of 28.7 months.
• What was Englich and Mussweiler (2001)'s conclusion?


  Anchoring bias may affect decision making when issuing a sentence, as the participants relied on the first piece of information when making decisions. Also supports DST as evidences system 1 thinking (fast, impulsive) and system 2 thinking (slow, rational)
• What are some strengths with Englich and Mussweiler (2001)'s study?


  It was a true experiment, allowing a cause and effect relationship to be determined

  Pilot study established reasonable anchors and also supported DST as demonstrated system 2 thinking as opposed to the actual study demonstrating system 1 thinking
• What are some weaknesses with Englich and Mussweiler (2001)'s study?


  Participant variability may have been present

  Difficult to generalise as small sample used