Miss Leslie Van Der Leer

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Research interests

Rational reasoning is often considered optimal, but sometimes it may pay to be irrational. In the optimism bias, people think that positive events are more likely than the evidence warrants. For example, law students, aware of high divorce rates, think their own marriage will last indefinitely. Furthermore, people tend to think that choosing their own numbers increases their chances of winning a lottery, despite the fact that the draw is not influenced by their choice of ticket numbers. Such positive illusions may be advantageous insofar as they maintain a positive self-view and prevent depression, which has been linked to a sense of a loss of control. Hence, in these situations, deviating from rational thinking could be beneficial.

However, sometimes deviating from rationality can lead to symptoms like delusions in schizophrenia, which are false beliefs held with strong conviction despite evidene on the contrary. A common finding is that delusional patients tend to jump to conclusions on the basis of too little evidence. If someone walks behind them, they might think that person is following them and plotting against them. A rationally reasoning person would consider the probability of this explanation versus the probabilities of other plausible explanations. In this case, deviating from rational reasoning does not seem beneficial as it can cause stress and discomfort to patients and people around them.

Overall, in my PhD I investigate how people update various irrational beliefs, focusing on delusion-proneness, evolutionary biases, unrealistic optimism, and self-deception. 


Weekly workshops and lab classes for PS1010 (Research methods in psychology). 

Educational background

BSc (Hons) in Physiology and Cognitive Neuroscience, with a minor in Psychology and a minor in Methods & Statistics - University College Utrecht (UCU), Utrecht, the Netherlands.

MSc in Cognitive Neuroscience - University College London (UCL), London, United Kingdom.

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  • Reviewer

    Activity: Ongoing editorial work / peer reviewPeer review of manuscripts

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    Activity: Conference contributionParticipation in conference

  • Poster presentation

    Activity: Conference contributionParticipation in conference

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