<p>According to the heuristics and biases approach, the representativeness heuristic (RH) is one of the heuristics available for assessing subjective probabilities (A. Tversky & D. Kahneman, 1974). A subjective probability assessed by the RH is determined by how representative the target object is of the target category. Several aspects of the RH are argued to cause systematic biases, for example: (<i>i</i>) When the RH is used, the category is represented by one single prototypical exemplar. This feature is argued to cause biases such as misperception of chance and insensitivity to sample size. (<i>ii</i>) The RH assesses the inverse rather than the conditional probability. This feature is argued to cause biases such as the conjunction fallacy and base-rate neglect.</p><p>The present thesis focuses on the cognitive aspects of the RH. Three studies were conducted. Overall, data indicated that the RH does not play a major role when subjective probabilities are assessed. Study I indicated that subjective probabilities are not typically determined by how representative the target object is of the target category. Study II indicated that the category is not represented by one single prototypical exemplar when subjective probabilities are assessed. Study III indicated that conjunction fallacies are not caused by the RH. </p><p>The results presented in Studies I-III cast serious doubts on the claim that subjective probabilities are routinely assessed using the RH. Rather, Studies I-II suggested that subjective probabilities are based on exemplar memory and Study III suggested that the conjunction fallacy is caused by people combining component probabilities in a an inappropriate way. In the General Discussion, it is suggested that people use a weighted average rule when combining component probabilities into conjunction probabilities. A simulation showing the ecological relevance of the weighted average rule is presented.</p>

According to the heuristics and biases approach, the representativeness heuristic (RH) is one of the heuristics available for assessing subjective probabilities (A. Tversky &amp; D. Kahneman, 1974). A subjective probability assessed by the RH is determined by how representative the target object is of the target category. Several aspects of the RH are argued to cause systematic biases, for example: (i) When the RH is used, the category is represented by one single prototypical exemplar. This feature is argued to cause biases such as misperception of chance and insensitivity to sample size. (ii) The RH assesses the inverse rather than the conditional probability. This feature is argued to cause biases such as the conjunction fallacy and base-rate neglect. The present thesis focuses on the cognitive aspects of the RH. Three studies were conducted. Overall, data indicated that the RH does not play a major role when subjective probabilities are assessed. Study I indicated that subjective probabilities are not typically determined by how representative the target object is of the target category. Study II indicated that the category is not represented by one single prototypical exemplar when subjective probabilities are assessed. Study III indicated that conjunction fallacies are not caused by the RH. The results presented in Studies I-III cast serious doubts on the claim that subjective probabilities are routinely assessed using the RH. Rather, Studies I-II suggested that subjective probabilities are based on exemplar memory and Study III suggested that the conjunction fallacy is caused by people combining component probabilities in a an inappropriate way. In the General Discussion, it is suggested that people use a weighted average rule when combining component probabilities into conjunction probabilities. A simulation showing the ecological relevance of the weighted average rule is presented.

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Tyrimo tikslas - palyginti vadovų racionalaus/intuityvaus kognityvinių stilių sąsajas su reprezentatyvumo ir pasiekiamumo euristikų panaudojimo dažnumu priimant sprendimus tyrime pateiktose užduotyse. Tyrime dalyvavo 152 Kauno mieste ar rajone dirbantys gyventojai (moterys ir vyrai), kurie buvo suskirstyti į dvi grupes: 1) vadovaujamas pareigas užimantys darbuotojai (N=85), vadovaujantys skirtingam darbuotojų skaičiui, iš kurių buvo 49 (57.6 proc.) moterys ir 36 (42.4 proc.) vyrai; 2) nevadovaujamas pareigas užimantys darbuotojai (N= 67), iš kurių buvo 38 (56.7 proc.) moterys ir 29 (43.3 proc.) vyrai. Tiriamieji turėjo užpildyti anonimines anketas, kuriose buvo panaudotos 2 skalės matuojančios racionalų/intuityvų kognityvinį stilių ir 3 užduotys, kuriose pasireiškia reprezentatyvumo ir pasiekiamumo euristikų panaudojimas. Tyrimo rezultatai parodė, kad reprezentatyvumo euristiką panaudoja dažniau vadovai turintys dominuojantį intuityvų kognityvinį stilių, bei didesnį darbo stažą turintys vadovai pasižymintys dominuojančiu racionaliu kognityviniu stiliumi. Tačiau tyrime reikšmingų skirtumų nebuvo rasta tarp lyties, amžiaus, kognityvinio stiliaus ir reprezentatyvumo euristikos panaudojimo dažnio. / The aim of the research is to compare the correlation between rational/intuitive cognitive styles and usage rate of representativeness and availability heuristics in managers' decision making according to the presented tasks. 152 people (men and women) working in Kaunas city or district have participated in the research. The participants were divided into two groups: 1) people working in management positions (N=85) supervising a different number of employees, this group consists of 49 (57.6 %) women and 36 (42.4 %) men; 2) people working in non-management positions (N= 67), 38 (56.7 %) women and 29 (43.3 %) men among them. Respondents had to fill in anonymous questionnaires which included two scales measuring rational/intuitive cognitive style and thee tasks revealing the usage of representativeness and availability heuristics. The results of the research show that representativeness heuristics is used more often by managers with dominating intuitive cognitive style and managers with higher work experience with dominating rational cognitive style. The research however did not reveal any significant distinctions in sex, age, cognitive style and usage rate of representativeness heuristic.

Previous research on human judgment and decision making has demonstrated systematic and predictable biases of judgment in experimental settings. One example of this is the tendency to intuitively violate the conjunction rule - a simple rule of probability. This was well illustrated in the famous Linda-problem. (Tversky &amp; Kahneman, 1983). According to the dual-process theory of reasoning, (Kahneman, 2011) reasoning fallacies such as the conjunction fallacy occurs when people fail to use analytic reasoning and instead overly rely on their intuition. The dual process theory proposes that cognitive processes underlying our intuitive impulses and our conscious reasoning constitutes two different modes in the mind –system 1 and system 2- and that the intuitive system 1 are not able to compute probabilities. Furthermore, it is assumed that processes that are labeled system 1 are fast whereas system 2 are thought to be slow. We tested these time course assumptions of dual process theory in a within-subject design by comparing response time latencies between conjunction fallacy judgments and accurate probability judgments. The results showed that inducing accurate responding did not result in delayed response latency. This indicates that making accurate probability judgments does not require more processing time which goes against what would be expected by the dual-process framework. / Tidigare forskning om mänskligt beslutsfattande och bedömningar har i experiment påvisat systematiska och förutsägbara bias. Ett exempel på detta är tendensen att intuitivt gå emot konjuktionsregeln- en enkel regel gällande sannolikhet. Detta illustrerades väl i det berömda Linda- problemet (Tversky &amp; Kahneman, 1983). Enligt två-systemsteorin (Kahneman, 2011) om problemlösning, uppstår bedömningsfel såsom konjuktionsfelet när människor inte använder sig av analytiskt tänkande och istället förlitar sig för mycket på sin intuition. Två-systemsteorin menar att de kognitiva processer som ligger till grund för våra intuitiva impulser och vårt medvetna resonerande utgör två olika aktörer i vårt tänkande- system 1 och system 2- och att det intuitiva system 1 inte kan beräkna sannolikheter. Processer som betecknas som tillhörande system 1 är enligt två-systemsteorin snabba medan system 2 föreställs vara ett långsamt system. I denna studie testades antagandet om tidsåtgång för de två systemen i en inomgruppsdesign genom att jämföra responstider mellan bedömningar där konjunktionsfelet begåtts och bedömningar där det inte begåtts. Resultaten visar att korrekta sannolikhetsbedömningar inte resulterar i långsammare responstider. Detta indikerar att det inte tycks vara mer tidskrävande att göra riktiga sannolikhetsbedömningar, vilket motsäger två-systemsteorins antagande om snabbt och långsamt processande.