Please read carefully the following names: John Lennon, Regula Meredith, George Bush, Woody Allen, Lara Holmes, Steven Spielberg, Anne Chirac, Helen Myers, Louis Armstrong, Elvis Presley, Elisabeth Dole, Lea Wright, Lory Hansen, Vivien Cosby, Leigh Ann Donovan, Kathy Lee, David Beckham, Charlie Chaplin, Tony Blair Availability The study by Tversky and Kahneman (1973):Tversky and Kahneman (1973): Did the list contain more names of men or of women? Did you come at a decision? Then look: There were 9 men and 10 women. Contributor© POSbase 2003

Two dependent variables:dependent variables  Free recall of the names Free recall  Estimate whether there were more male or female names Availability The authors presented a tape-recorded list with 39 names.  Condition 1: 19 famous male names and 20 less famous female names  Condition 2: 19 famous female names and 20 less famous male names © POSbase 2003

 Among the 99 participants who compared the frequency of men and women in the lists, 80 erroneously believed that the class consisting of the more famous names was more frequent.  A sign test revealed that both differences were significant Availability The results were clear-cut:  Of 86 participants in the recall condition, 57 recalled more famous than less famous names, and only 13 recalled fewer famous names than less famous names. © POSbase 2003

The availability heuristic is one of the famous heuristics proposed by the two authors, along with the representativeness heuristic and anchoring and adjustment.representativeness heuristicanchoring and adjustment Availability The authors concluded that people use the availability heuristic: Famous names were more likely to come to mind; therefore, the participants overestimated the class consisting of the more famous names. © POSbase 2003

You will be given several letters of the alphabet, and you will be asked to judge whether these letters appear more often in the first or in the third position, and to estimate the ratio of the frequency with which they appear in these positions (Tversky & Kahneman, 1973, p. 211f). They presented the letters K, L, N, R, and V, all of them occurring more frequently in the third than in the first letter position in English words. Availability In another classic experiment that demonstrates the availability heuristic, Tversky and Kahneman (1973) asked participants to judge letter frequencies: © POSbase 2003

Availability Two dependent variables: Decision whether a certain letter is more likely to appear in the first or in the third position. Estimate of the ratio of these two values, e.g., R’s in the first position divided by R’s in the third position. Results: 105 from 152 participants judged the first position to be more likely for the majority of letters. Each of the five letters was judged to be more frequent in the first rather than in the third position, with a median ratio of about 2:1, despite the fact that each letter was more frequent in the third position. © POSbase 2003

Availability As it is easier to retrieve letters in the first position than letters in the third position, the authors explained the preference for the first position with the use of the availability heuristic. Sedlmeier et al. (1998) critically examined the availability heuristic by extending the letter frequency study, but did not find an effect of availability on frequency estimates, whereas Wänke et al. (1995) did find an effect. However, availability is not the only way to come to frequency estimates (Brown, 1995; Hasher and Zacks, 1979). Availability is the ease of recall, but it is often confounded with amount of recall, an issue further analyzed by Schwarz et al. (1991).Schwarz et al. (1991) © POSbase 2003

Availability There are many applications of the availability heuristic in the literature:  Frequency estimates of lethal events (Lichtenstein et al., 1978)Lichtenstein et al., 1978  Estimates of temporal distance of events (Brown et al., 1985)Brown et al., 1985  Spontaneous generation of numbers (Kubovy, 1977)  Stereotype formation (Rothbart et al., 1978)  Estimates of one’s own contribution to group work (Ross & Sicoly, 1979)Ross & Sicoly, 1979  Weighing of evidence (Reyes et al., 1980)  Sex Typing (Bem, 1981)  Unrealistic optimism (Weinstein, 1980)  The fundamental attribution error (Ross, 1977) © POSbase 2003