Does thinking make you biased? The case of the engineers and lawyers problem

Does thinking make you biased? The case of the engineers and lawyers problem Kinga Morsanyi (km574@cam.ac.uk) Department of Experimental Psychology, University of Cambridge Downing street, Cambridge, CB2 3EB, UK Simon J. Handley (S.Handley@plymouth.ac.uk) School of Psychology, University of Plymouth Drake Circus, Plymouth, PL4 8AA, UK Abstract In this study we examined the cognitive processes involved in engineers and lawyers-type problems, using a novel method (i.e., asking for liking ratings). We were particularly interested in how participants process information about personality descriptions and base rates, which are provided in the problems. In line with previous research, we found that people detect the conflict between descriptions and base rates. Nevertheless, when instructed to reason logically, instead of relying on base rates, participants resolved the conflict by showing higher preference for description-based responses. Keywords: conflict detection; dual-process theories: engineers and lawyers problem; heuristics and biases; instruction manipulation; liking ratings. Dual process theories of reasoning and decision making (e.g., Evans & Over, 1996; Stanovich, 1999) propose that higher order cognition is based on two qualitatively different types of process. Type 1 (i.e., heuristic) processes are assumed to operate fast and automatically with little demand of cognitive capacity, whereas Type 2 processes are slow, conscious, and demanding of computational resources. The tasks used in the heuristics and biases literature (see e.g., Kahneman, Slovic & Tversky, 1982) can be answered by giving a heuristic-based response, or a response which corresponds to a normative rule of probability (although some theorists have questioned the assumption that giving probability-based responses to these problems is more normative than giving description-based responses – see e.g., Hertwig & Gigerenzer, 1999). Kahneman and Frederick (2005) used these tasks as illustrations for Type 1 and 2 processes at work. For example, consider the classic engineers and lawyers problem (Kahneman & Tversky, 1973; see Table 1.). In the original (conflict) problem, base rate information, which strongly favors lawyers, is presented together with a stereotypical description of an engineer. When participants are asked to decide if the person is more likely to be an engineer or a lawyer, they tend to give the response which corresponds to the description . An interesting question is whether participants experience a conflict while they solve these tasks, or if they just give the first response that comes to mind. Dual-process theorists (e.g., Evans, 2006) assume that, as Type 1 processes operate quickly and automatically, all participants are inclined to give a Type 1 response by default. Nevertheless, some individuals (usually the ones of higher cognitive ability – see e.g., Stanovich & West, 2000) are able to inhibit this initial response tendency, and give a response which is based on Type 2 computations. Thus, participants who eventually give a normative response are expected to experience a strong conflict between Type 1 and 2 response tendencies. However, what happens in the case of the majority of the participants who give a heuristic response (which is supposed to be delivered by Type 1 processes)? Do they experience any inner struggle, or do they simply give the first response that comes to mind without ever considering probabilistic information? In a number of recent studies De Neys and colleagues (e.g., De Neys, Cromheeke & Osman, 2011; De Neys & Glumicic, 2008) used different versions of the engineers and lawyers problem (see Table 1 for illustrations). Besides the original version, they also developed a non-conflict task where base-rates and the description pointed to the same response, and they also used a neutral task where base rate information was presented together with a description which had no relevance to the choice options. Note that neutral problems typically elicit the response of “both options are equally likely” (which is considered a heuristic response). The reason that participants ignore base rates even when they are not provided with any other useful information is, presumably, that they try to base their response on the description (which they automatically assume to be relevant, although it is not). Thus, providing an irrelevant description is enough to draw participants’ attention from the base rates. De Neys and Glumicic (2008) stated that even people who eventually give a description-based response show signs of conflict detection, although they are not consciously aware of this. They demonstrated that whereas in verbal protocols there was no mention of experiencing a conflict, less explicit measures showed signs of differential processing of base rates in conflict and non-conflict problems. The purpose of the present study was to investigate further how people process base rate-information in the presence of base rate-congruent, incongruent, and neutral descriptions. In the experiment that we report below we used the problems developed by De Neys and Glumicic (2008) which we slightly modified to make them more appropriate for UK participants. However, instead of asking participants to generate a response, we provided them with a response (which we called a statement), and we asked them