TVERSKY AND KAHNEMEN 1974

• DUAL PROCESS MODEL:

  • when we make a decision we either use system 1 or 2 thinking.
  • system 1: quick, relies on past experience or mental short cuts called heuristics
  • system 2: more rational, using logic and reasoning. slow.
• ANCHORING EFFECT: when people rely too heavily on the first piece of information they receive (the anchor) when making decisions
• heuristic: a rule of thumb that helps us to solve problems quickly but may not always be accurate.
• cognitive biases are systematic errors in thinking that affects the decisions and judgments that people make. we are prone to these because firstly we are cog misers- we don't have the time/desire/resources to make a decsion hence we use heuristics. biasesinfluence our excision making because o ego depletion-lack of self control or will power. when our cog load is too high we demonstrate cog biases (this means that we have too many things on our mind in our working memory and this doesn't allow us the mental resources to reason out a solution
• ANCHORING BIAS: the tendency to rely on the first piece of information that comes to mind. to rely too heavily on the first piece of information offers-the anchor when making decisions. during decision making, anchoring occurs when individuals use an initial piece of info to make judgments. the use of anchors has many different effects on behavour
• TVERSKY AND KAHNMEN 1974 STUDY

  high school students=particpants

  participants in ascending condition were asked to quickly estimate the value of 1*2*3*4*5*6*7*8 in 5 seconds

  those in descending condition were asked to quickly estimate the value of 8*7*6*5*4*3*2*1.

  • since we read from left to right, the researchers assumed that group 1 would use "1" as an anchor and predict a lower value that the group that started with "8" as an anchor.
  • estimation= first number seen would bias the estimate value by the participant
• researchers fund that the median for the ascending goroup was 512

  the median for descending group was 2240

  the actual value is 40320!!
• EVALUATION

  • very simple experiment, easily replicated, allows establishing the reliability of the results
  • study is highly controlled, has high internal validity- can be inferred that the anchor was the cause of the higher/lower estimates by the students
  • low ecological validity- situation is very artificial, its not often in life that we only have 5 seconds to estimate the value of something. its questionable to what extent the findings can be applied
• EVALUATION CONTINUATION

  • researchers used median to report the data- allowed the researchers to diminish influence of outliers on the reporting data
  • independent samples design: participant variability may have played role in results, it'd be better to have matched pairs design to have 2 grps with an equal level of math competency