That delusion-prone people frequently jump to conclusions ranks among the key discoveries in the scientific literature on delusions. However, believing the matter has not been sufficiently investigated, a group of researchers from Royal Holloway, University of London set out to clarify the link between delusion and the tendency to jump to conclusions. While their findings are not surprising, they are certainly entertaining: “Most people jump to conclusions, but more delusion-prone individuals ‘jump further,’” wrote the authors in their conclusion.
Delusions (that are not due to a medical condition or substance abuse) may seem believable at face value, and delusional people may appear normal as long as you don’t touch upon their delusional themes, Psychology Today states. According to the DSM–IV–TR, “delusional conviction occurs on a continuum and can sometimes be inferred from an individual’s behavior.” These are contemporary perspectives, but they are rooted in the work of Karl Jaspers, a German psychiatrist and philosopher, who believed delusions to be distinct from normal beliefs. Delusions are “impervious to counterargument,” he argued, because such a change in “belief fixation” amounted to “an alteration of the personality.” His criteria for true delusion were:
- certainty (held with absolute conviction)
- incorrigibility (not changeable by compelling counterargument or proof to the contrary)
- impossibility or falsity of content (implausible, bizarre or patently untrue).
Making the Leap
For the current study, researchers led by PhD student Leslie van der Leer enlisted the help of roughly a hundred students at Royal Holloway, University of London. The students completed tests measuring their intelligence, their level of risk aversion and their proneness to delusion. Then the students participated in an “incentivized probabilistic reasoning task” in which a combination of rewards and penalties generated an optimal decision point. The experiment worked like this: the students had to look at a fish, and then say whether it had been caught in one of two different lakes. Since they received a reward for every correct answer and penalized for each question they asked, there existed an optimal point when the number of questions did not eat up all the money of a correct answer. And because there was a perfect moment at which to make the decision, the researchers could see when each participant made the leap to a hasty conclusion.
Analyzing the data, the researchers found the results to be expected. The participants who were most delusion-prone made earlier decisions than those less prone to delusion.
“People who suffer from delusions have unjustified, and sometimes bizarre, beliefs about themselves and the world,” explained Dr Ryan McKay, from the Department of Psychology at Royal Holloway. “A tendency to gather insufficient evidence when forming beliefs, and making decisions, is thought to be a core cognitive component of delusion formation.” Noting the results of the experiment confirm this view, McKay added, “This indicates that they would rush to make choices in their everyday lives, relating to anything from money or jobs to family and friends, which could lead to less successful outcomes for them.”
Though it confirmed the status quo, the study also contained one minor surprise. Since in the past researchers only compared the decisions of delusion-prone people to those of non-delusion-prone people, this study arrived at a new insight simply by comparing all the participants to an objective measure. “Even low delusion-prone people jumped to conclusions — so most people jump to conclusions, but delusion-prone people jump further,” McKay said.
Source: van der Leer L, Hartig B, Goldmanis M, McKay R. Delusion‐Proneness and ‘Jumping to Conclusions:’ Relative and Absolute Effects. Psychological Medicine. 2014.