Rodrigo Moro

On the nature of the conjunction fallacy

In a seminal work, Tversky and Kahneman showed that in some contexts people tend to believe that a conjunction of events (e.g., Linda is a bank teller and is active in the feminist movement) is more likely to occur than one of the conjuncts (e.g., Linda is a bank teller). This belief violates the conjunction rule in probability theory. Tversky and Kahneman called this phenomenon the “conjunction fallacy”. Since the discovery of the phenomenon in 1983, researchers in psychology and philosophy have engaged in important controversies around the conjunction fallacy. The goal of this paper is to explore the most important of these controversies, namely, the controversy about the nature of the conjunction fallacy. Is the conjunction fallacy mainly due to a misunderstanding of the problem by participants (misunderstanding hypothesis) or is it mainly due to a genuine reasoning bias (reasoning bias hypothesis)? A substantial portion of research on the topic has been directed to test the misunderstanding hypothesis. I review this literature and argue that a stronger case can be made against the misunderstanding hypothesis. Thus, I indirectly provide support for the reasoning bias hypothesis.

Sets or frequencies? How to help people solve conditional probability problems

Since the 1970s, the Heuristics and Biases Program in Cognitive Psychology has shown that people do not reason correctly about conditional probability problems. In the 1990s, however, evolutionary psychologists discovered that if the same problems are presented in a different way, peoples performance greatly improves. Two explanations have been offered to account for this facilitation effect: the natural frequency hypothesis and the nested-set hypothesis. The empirical evidence on this debate is mixed. We review the literature pointing out some methodological issues that we take into account in our own present experiments. We interpret our results as suggesting that when the mentioned methodological problems are tackled, the evidence seems to favour the natural frequency hypothesis and to go against the nested-set hypothesis.

La teoría de juegos conductual, el dilema del viajero alternativo y la maximización de pagos

Dentro del area de teoria de juegos conductual nos enfocamos en un contexto especifico, el del juego que denominamos Dilema del viajero alternativo. En este contexto hemos observado que los participantes tienden a elegir estrategias estrictamente dominadas. Para explicar tendencias similares en otros juegos, los investigadores del area han apelado a sesgos cognitivos o bien a factores motivacionales. Proponemos un factor psicologico denominado sesgo en la accesibilidad de objetivos para explicar las tendencias en cuestion. Ese factor involucra tanto aspectos cognitivos como motivacionales. Presentamos una sintesis de resultados experimentales que favorecen dicha explicacion sobre otras alternativas mas frugales.