Anchor effect

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Anchor effect ( english anchoring effect ) is a term used in cognitive psychology for the fact that people are influenced at deliberately chosen numerical values of currently existing environmental information without having them become aware of this influence. The surrounding information has an influence even if it is actually irrelevant for the decision. So it is an effect in which the judgment is based on an arbitrary anchor. The result is a systematic distortion in the direction of the anchor.

Anchors can work in two different ways:

  • As an unconscious suggestion, the anchor activates associations that suit it , which then influence the decision-making process, i.e. via the priming mechanism .
  • The anchor provides the starting point or starting value for a conscious train of thought that should lead to a rationally justified judgment. Then we speak of adjustment heuristic (Engl. Adjustment heuristic ).

Definition anchor

The anchor is specific information. The information can be formed by the person himself from the circumstances or obtained from another person, or it is present purely by chance. This information is crucial when assessing a situation and making a decision. It does not matter whether the information is actually relevant and useful for a rational decision.

Tversky / Kahneman provided evidence for the first time that even an arbitrarily placed anchor influences an individual in the decision-making process. If anchors have an impact on the decision despite their irrelevance, this is referred to in the literature as the “basic anchoring effect” (Brewer / Chapman; Wilson et al.).

On the basis of various studies and experiments, it was made clear that the anchoring effect is a very robust phenomenon in decision-making processes, which can occur in a wide variety of situations.

Measure of the effect of the anchor

A measure of how strongly an anchor affects the decision, the anchor index , can be calculated as follows: Difference in the selected numerical values ​​divided by the difference in anchor numbers. Usually the result is expressed as a percentage. Theoretically possible extreme values ​​would be:

  • The respondents are not influenced by the anchor numbers at all, but all give the same answer (for example the correct value). Then the difference in the numerator is zero and thus the anchor index is 0%.
  • The respondents are completely influenced by the anchor numbers; their answers are identical to these. Then the numerator is equal to the denominator, the quotient is 1 and thus the anchor index is 100%.

Examples

  • Test subjects should estimate the size of the tallest giant sequoia . Half of the group that got 1200 ft. Anchored estimated an average of 844 ft .; the other half, anchored 180 feet, estimated an average of 282 feet. Difference in estimates: 562; Difference in numbers of anchors: 1020; Quotient: 0.55; Anchor index: 55%.
  • Visitors to the Exploratorium were asked how much money they would donate to rescue seabirds from an oil spill . One group was given the anchor number 5 (wrapped in the question "Would you be willing to give $ 5?"); this group wanted to give an average of $ 20. Another group received the anchor 400; this group wanted to give an average of $ 143. Calculation: (143 - 20): (400 - 5) = 0.31 → anchor index 31%.

Studies and Examples

In the first study on anchoring by Tversky and Kahneman, the test subjects were given a random number (between 0 and 100) as a numerical anchor by turning a wheel of fortune. Then they should estimate whether the percentage of African UN member states is above or below this number. Then the test persons were asked to give an exact estimate, i.e. what percentage of the members of the United Nations are actually African countries. The results were astonishing, because the anchors previously obtained by turning the wheel of fortune had a significant influence on the estimates. The mean value of estimates given by people whose wheel of fortune number (anchor) was 65 was 45%. People who received an anchor of 10 estimated the proportion of African UN member countries at an average of only 25%. This study has shown that in number estimates, a previously transmitted random number influences the estimate.

Another example from Daniel Kahneman : When subjects are asked to first memorize the last two digits of their social security number and then estimate the number of doctors in New York, the correlation between the two numbers is about 0.4 - far more than that Would correspond to chance. Just thinking about the first number affects the second, even though there is no logical connection between the two.

Experts are also subject to the anchor effect

In the study by Northcraft / Neale it was investigated, among other things, whether the anchor effect had a weaker effect on test participants, who are experts in the field to be examined, than on test persons, whose knowledge of the topic to be examined is limited. Two groups of participants were formed to estimate real estate prices: students and real estate experts. The participants in both groups were given a ten-page information brochure about the property to be valued. The information contained therein contained all information about the facts necessary for the assessment and was identical for all test participants, only the specified list price differed. Above all, it should be checked whether the list price influences the estimates of the real value of real estate. The results of this study showed that both groups, both amateurs and experts, were strongly influenced in their decisions by the quoted list prices.

Birte Englich and Thomas Mussweiler were able to show that the verdict of judges, who all had more than 15 years of professional experience, was based significantly on the arbitrary recommendation of a layperson (computer science student in the first semester) or even on a random number (determined with marked dice). The strength of the anchor effect when rolling the dice was 50%.

Explanation

Amos Tversky and Daniel Kahneman considered the anchor effect to be caused by an insufficient adjustment of the judgment influenced by the anchor. In later studies, Thomas Mussweiler and Fritz Strack showed that the anchor task activates memory content that matches the anchor number and can be easily retrieved from memory for subsequent judgments (“selective availability”). Example: A judge has to determine the sentence for a rapist. A high number of anchors activates reminders of details of the crime that aggravate the offense, a low number of mitigating details.

relevance

Economy and work

The decision-distorting anchoring effect occurs in practice especially when decisions are made in connection with numerical information values. This is particularly true in economic areas in which decisions are often linked to numerical values.

Anchors can play a crucial role in negotiation situations. The subjective loss or profit situation z. B. often depends on the first offer, which can significantly influence the further negotiation process (Kristensen / Gärling; Moran / Ritov; Ritov). It could be shown that people can achieve more advantageous results in negotiations if they made the first offer. This knowledge makes it possible to use the knowledge of the anchoring effect to target reference and anchor points, and to control and influence negotiations. The anchor effect also occurs in the context of crowdsourcing. For example, displaying the average rating of other people, which served as an anchor, when assessing business model ideas in an online experiment, led people to orientate themselves more towards the anchor displayed. As a result, the variance of the following ratings was reduced. This anchor effect was more pronounced for high quality ideas than for lower quality ideas.

Another aspect of the anchoring theory that is relevant for business is suggestive anchors in work orders. Suggestive numerical targets that generate an anchoring can exert a significant influence on motivation and performance (Locke / Latham; Hinsz / Kalnbach / Lorentz).

An experiment by Russo and Schoemaker, actually conducted for the purpose of examining anchoring among experts, shows the effects of anchoring in business life. Experts had to give estimates of the best possible interest rates in six months. It turned out that they too were subject to the anchoring effect. This in turn illustrates the risk of false prognoses and false speculations on an economic level due to the anchoring effect that distorts judgment.

In the area of buying and selling decisions, the phenomenon of anchoring and adaptation represents a decision distortion that is relevant to the economy. In a number of studies, be it in retail or in the real estate and used car industry, numerical values ​​have a significant anchoring effect on buying and selling Sales prices or quantities sold can be proven (cf. Kristensen / Gärling; Mussweiler / Strack / Pfeiffer; Northcraft / Neale; Wansink / Kent / Hoch).

Law

The influence of numerical and causal anchors in court hearings is another practical aspect of anchoring. Chapman / Bornstein were able to prove in their study that the phenomenon of anchoring and adaptation also occurs in court judgments. Claims for damages, for example, serve as an anchor from which the amount actually paid out is determined.

See also

literature

  • Stepan Bahnik, Birte Englich, Fritz Strack: Anchoring effect, in: Rüdiger F. Pohl (Ed.): Cognitive illusions: Intriguing phenomena in thinking, judgment and memory. 2nd Edition. Routledge, London and New York 2017, ISBN 978-1-138-90341-8 , pp. 223-241.
  • Birte Englich: Anchor effects in a legal context. In: Hans Werner Bierhoff: Handbook of social psychology and communication psychology. Göttingen, Hogrefe 2006, ISBN 3-8017-1844-1 , pp. 309-313 (Handbuch der Psychologie, 3, PDF file; 2.27 MB ).
  • Birte Englich: Blind or Biased? Justitia's Susceptibility to Anchoring Effects in the Courtroom Based on Given Numerical Representations. In: Law & Policy , Volume 28 (4), 2006, ISSN  0265-8240 , pp. 497-514 ( PDF file; 136 kB ).
  • Daniel Kahneman : Thinking, fast and slow , Allen Lane Paperback, ISBN 978-1-84614-606-0 , therein Chapter 11: Anchors , pp. 119-128
  • Thomas Mussweiler and Fritz Strack : Comparing is Believing: A Selective Accessibility Model of Judgmental Anchoring. In: European Review of Social Psychology , Vol. 10, 1999, pp. 135-167.

Individual evidence

  1. ↑ Amos Tversky, Daniel Kahneman: Judgment under Uncertainty: Heuristics and Biases . In: Science . tape 185 , no. 4157 , September 27, 1974, ISSN  0036-8075 , p. 1124–1131 , doi : 10.1126 / science.185.4157.1124 , PMID 17835457 ( caltech.edu [PDF; accessed October 21, 2019]).
  2. ^ Noel T. Brewer, Gretchen B. Chapman: The fragile basic anchoring effect . In: Journal of Behavioral Decision Making . tape 15 , no. 1 , 2002, ISSN  1099-0771 , p. 65-77 , doi : 10.1002 / bdm.403 .
  3. ↑ Timothy D. Wilson, Christopher E. Houston, Kathryn M. Etling, Nancy Brekke: A new look at anchoring effects: Basic anchoring and its antecedents. In: Journal of Experimental Psychology: General . tape 125 , no. 4 , 1996, ISSN  1939-2222 , pp. 387–402 , doi : 10.1037 / 0096-3445.125.4.387 ( semanticscholar.org [PDF; accessed October 21, 2019]).
  4. ↑ a b Karen E. Jacowitz, Daniel Kahneman: Measures of Anchoring in estimation tasks . In: Personality and Social Psychology Bulletin . tape 21 , no. November 11 , 1995, ISSN  0146-1672 , pp. 1161-1166 , doi : 10.1177 / 01461672952111004 .
  5. ↑ a b Gregory B North Craft, Margaret A. Neale: Experts, amateurs, and real estate: An anchoring-and-adjustment perspective on property pricing decisions . In: Organizational Behavior and Human Decision Processes . tape 39 , no. 1 , February 1, 1987, ISSN  0749-5978 , p. 84–97 , doi : 10.1016 / 0749-5978 (87) 90046-X ( missouri.edu [PDF; accessed October 21, 2019]).
  6. ^ B. Englich, Th. Mussweiler: Sentencing under uncertainty: Anchoring effects in the court room. ( Memento of May 13, 2012 in the Internet Archive ) In: Journal of Applied Social Psychology , 31, 1535–1551 (PDF; 1.2 MB)
  7. ↑ Englich, B., Mussweiler, T., Strack, F. (2006): Playing dice with criminal sentences: The influence of irrelevant anchors on experts' judicial decision making. ( Memento of May 13, 2012 in the Internet Archive ) In: Personality and Social Psychology Bulletin , 32, 188–200 (PDF; 121 kB)
  8. ^ Fritz Strack, Thomas Mussweiler: Explaining the enigmatic anchoring effect: Mechanisms of selective accessibility. In: Journal of Personality and Social Psychology . tape 73 , no. 3 , 1997, ISSN  0022-3514 , pp. 437–446 , doi : 10.1037 / 0022-3514.73.3.437 ( ufl.edu [PDF; accessed on October 21, 2019]).
  9. ↑ Elliot Aronson , Timothy D. Wilson, Robin M. Akert: Social Psychology ; 4th edition 2004; Translated from the English by Eva Aralikatti. Pearson study. ISBN 3-8273-7084-1
  10. ^ A b Henrik Kristensen, Tommy Gärling: The Effects of Anchor Points and Reference Points on Negotiation Process and Outcome . In: Organizational Behavior and Human Decision Processes . tape 71 , no. 1 , July 1, 1997, ISSN  0749-5978 , p. 85–94 , doi : 10.1006 / obhd.1997.2713 ( gu.se [PDF; accessed on October 21, 2019]).
  11. ↑ Simone Moran, Ilana Ritov: Initial perceptions in negotiations: evaluation and response to? Logrolling? offers . In: Journal of Behavioral Decision Making . tape 15 , no. 2 , April 2002, ISSN  0894-3257 , p. 101–124 , doi : 10.1002 / bdm.405 ( huji.ac.il [PDF; accessed October 21, 2019]).
  12. ↑ Ilana Ritov: Anchoring in Simulated Competitive Market Negotiation . In: Organizational Behavior and Human Decision Processes . tape 67 , no. 1 , July 1, 1996, ISSN  0749-5978 , p. 16–25 , doi : 10.1006 / obhd.1996.0062 ( semanticscholar.org [PDF; accessed October 21, 2019]).
  13. ↑ T. Goerzen, D. Kundisch: When in Doubt Follow the Crowd: How Idea Quality Moderates the Effect of an Anchor on Idea Evaluation . In: ICIS 2017 Proceedings . October 30, 2017 ( aisnet.org ).
  14. ^ Edwin A. Locke, Gary P. Latham (1990): Work Motivation: The High Performance Cycle. In: Kleinbeck, Uwe; et al. (1990): Work motivation , Hillsdale, NJ, USA: Lawrence Erlbaum Associates, pp. 3-25
  15. ↑ Verlin B Hinsz, Lynn R Kalnbach, Nichole R Lorentz: Using Judgmental Anchors to Establish Challenging Self-Set Goals Without Jeopardizing Commitment . In: Organizational Behavior and Human Decision Processes . tape 71 , no. 3 , September 1, 1997, ISSN  0749-5978 , p. 287–308 , doi : 10.1006 / obhd.1997.2723 ( sciencedirect.com [accessed October 21, 2019]).
  16. ^ Edward J. Russo, Paul JH Schoemaker (1990): Decision Traps: The Ten Barriers to Brilliant Decision-Making and How to Overcome Them , Fireside, New York
  17. ^ Thomas Mussweiler, Fritz Strack, Tim Pfeiffer, Overcoming the Inevitable Anchoring Effect: Considering the Opposite Compensates for Selective Accessibility . In: Personality and Social Psychology Bulletin . tape 26 , no. November 9 , 2000, ISSN  0146-1672 , pp. 1142–1150 , doi : 10.1177 / 01461672002611010 ( researchgate.net [accessed October 21, 2019]).
  18. ↑ Brian Wansink, Robert J. Kent, Stephen J. Hoch: An Anchoring and Adjustment Model of Purchase Quantity Decisions . In: Journal of Marketing Research . tape 35 , no. 1 , 1998, ISSN  0022-2437 , p. 71–81 , doi : 10.2307 / 3151931 ( psu.edu [PDF; accessed October 21, 2019]).
  19. ↑ Gretchen B. Chapman, Brian H. Bornstein: The More You Ask For, the More You Get: Anchoring in Personal Injury Verdicts . In: Applied Cognitive Psychology . tape 10 , no. 6 , 1996, ISSN  1099-0720 , pp. 519-540 , doi : 10.1002 / (SICI) 1099-0720 (199612) 10: 63.0.CO; 2-5 ( communicationcache.com [PDF; accessed October 21, 2019]).