The Myth of the Optimism Bias?

This article was originally posted by ‘Neuroskeptic’ on on 3 June 2016. The article discusses research on optimism bias, as carried out by a team of psychological researchers including Birkbeck’s Professor Ulrike Hahn.

OptimismAre humans natural, irrational optimists? According to many psychologists, humans show a fundamental optimism bias, a tendency to underestimate our chances of suffering negative events. It’s said that when thinking about harmful events, such as contracting cancer, most people believe that their risk is lower than that of ‘the average person’. So, on average, people rate themselves as safer than the average. Moreover, people are also said to show biased belief updating. Faced with evidence that the risk of a negative outcome is higher than they believed, people don’t increase their personal risk estimates properly.

But now a group of researchers, led by first author Punit Shah of London, hascriticized the theory of biased belief updating and, by extension, the whole optimism bias model. Shah et al. say that optimism bias may be a mere statistical artifact, a product of the psychological test paradigms used to assess it. They argue that even perfectly rational, unbiased individuals would seem ‘optimistic’ in these tests. Specifically, the authors say that the apparent optimism is driven by the fact that negative events tend to be uncommon.

The new work builds on a 2011 paper by Adam J. L. Harris and Ulrike Hahn, also authors of the present paper. The 2011 article criticized the claim that people show an optimism bias by rating themselves as safer than the average. The new paper takes aim at biased belief updating. Here’s how Shah et al. describe their argument:

New studies have now claimed that unrealistic optimism emerges as a result of biased belief updating with distinctive neural correlates in the brain. On a behavioral level, these studies suggest that, for negative events, desirable information is incorporated into personal risk estimates to a greater degree than undesirable information (resulting in a more optimistic outlook).


However, using task analyses, simulations and experiments we demonstrate that this pattern of results is a statistical artifact. In contrast with previous work, we examined participants’ use of new information with reference to the normative, Bayesian standard.


Simulations reveal the fundamental difficulties that would need to be overcome by any robust test of optimistic updating. No such test presently exists, so that the best one can presently do is perform analyses with a number of techniques, all of which have important weaknesses. Applying these analyses to five experiments shows no evidence of optimistic updating. These results clarify the difficulties involved in studying human ‘bias’ and cast additional doubt over the status of optimism as a fundamental characteristic of healthy cognition.

I asked Shah and his colleagues to explain the case against the optimism bias in belief updating in a nutshell. They said

All risk estimates have to fit into a scale between 0% and 100%; you can’t have a chance of getting a heart attack at some point in your life of less than 0% or greater than 100%. The problems for the update method arise from the fact that the same ‘movement’ in percentage terms means different things in different parts of the scale.


Someone whose risk decreases from 45% to 30% has seen their risk cut by 1/3, whereas someone whose risk increases from 15% to 30% has seen their risk double -much bigger change. So the same 15% difference means something quite different if you have to revise your beliefs about your individual risk downwards (good news!) or upwards (bad news!) toward the same percentage value. The moment people’s risk estimates are influenced by individual risk factors (a family history of heart attack increases your personal risk by a factor of about 1.6), people should change their beliefs to different amounts, depending on the direction of the change. The update method falsely equates the 15% in both cases.


If the difference in belief change simply reflects these mathematical properties of risk estimates then one should see systematic differences between those increasing and those decreasing their risk estimates regardless of whether they happen to be estimating a negative or a positive event. But in the first case, this will look like ‘optimism’, in the second case it will look like ‘pessimism’. This is the pattern our experiments find…


The evidence base thus seems far less stable than previously considered. There is, using various paradigms, plenty of evidence for optimism in various real-world settings such as sports fans predictions and political predictions, but these just show that certain people might be optimistic in certain situations, not that there is a general optimistic tendency across situations that would be required to say people are optimistically biased. It is also important to note that because this belief updating paradigm has been used in so many neuroscience studies, it means those neuroscience data are also uninterpretable.

Read the original article on

Read the original article on

In my view, Shah et al. make a strong case that the evidence for optimism bias needs to be reexamined. Their argument makes a crucial prediction: that people should show a ‘pessimistic’ bias (the counterpart of the optimism bias) when asked to rate their chance of experiencing rare, positive events. In the new paper, the authors report finding such a pessimistic bias in a series of experiments. But perhaps they should team up with proponents of the optimism bias and run an adversarial collaboration to convince the believers.

  • Punit Shah, Adam J. L. Harris, Geoffrey Bird, Caroline Catmur, & Ulrike Hahn (2016). A Pessimistic View of Optimistic Belief Updating Cognitive Psychology
. Reply . Category: Categories, Science . Tags: , ,

Make fear your friend

This post was contributed by Professor Naz Derakhshan of Birkbeck’s Department of Psychological Sciences


“Fear is often thought of as a negative emotion, but a new idea in psychology suggests that using it the right way can turn it into an incredibly positive force in your life.”


So starts a three page health feature article in the February edition of Top Sante. Showcasing the expertise of Birkbeck’s Prof Naz Derakhshan, the article posits that  fear can be turned into a positive force in our lives – all we need to do is listen to it, trust in it, and learn from it. In other words, we need to befriend it.

“Instead of thinking of fear solely as a negative emotion, embrace it as an
important warning system,’ says Professor Derakhshan in the article. “Being afraid of something is a signal that its consequence is important to you so it should be attended to.”
Click below to read the full piece, which includes some handy tips on how to welcome fear as a positive friend in your life, and how to ultimately become its boss.
Make Fear Your Friend - page 1 (article copyright of Top Sante)

Make Fear Your Friend – page 1 (article copyright of Top Sante)


Make Fear Your Friend - page 2 (article copyright of Top Sante)

Make Fear Your Friend – page 2 (article copyright of Top Sante)


Find out more

. 1 comment . Category: Categories, Science . Tags: , , ,

Adolescents and multitasking

This post was contributed by Dr Iroise Dumontheil of Birkbeck’s Department of Psychological Sciences, and co-author of the newly published study “Multitasking during social interaction in adolescence and early adulthood”. The paper, published in Royal Society Open Science, can be read hereClick here to read the news article

Presentation of multitasking paradigm (published in Royal Society Open Science)

Presentation of multitasking paradigm (published in Royal Society Open Science) * Caption below

Humans are social beings. We have evolved to function in groups of various size. Some researchers argue that the complexity of social relationships which require, for example, remembering who tends to be aggressive, who has been nice to us in the past, or who always shares her food, may have been an evolutionary pressure leading to the selection of humans with bigger brains, and in particular a bigger frontal cortex (see research by Robin Dunbar).

However, we do not always take into account the perspective or knowledge of a person we are interacting with. Boaz Keysar and later Ian Apperly developed an experimental psychology paradigm which allows us to investigate people’s tendency to take into account the perspective of another  person (referred to as the “director”) when they are following his instructions to move objects on a set of shelves. Some of the slots on the shelves have a back panel, which prevent the director, who is standing on the other side of the shelves, from seeing, and knowing, which objects are located in the slots. While all participants can correctly say, when queried, which object the director can or cannot see, adult participants, approximately 40% of the time, do not take into account the view of the director when following his instructions.

In a previous study, Sarah-Jayne Blakemore (UCL), Ian Apperly (University of Birmingham) and I, demonstrated that adolescents made more errors than adults on the task, showing a greater bias towards their own perspective.  In contrast,  adolescents performed to the same level a task matched in terms of general demands but which required following a rule to move only certain objects, and did not have a social context (read the study here).

The Royal Society Open Science journal is publishing today a further study on this topic, led by Kathryn Mills (now at the NIMH in Bethesda) while she was doing her PhD with Sarah-Jayne Blakemore at UCL. Here, we were interested in whether loading participants’ working memory, a mental workspace which enables us to maintain and manipulate information over a few seconds, would affect their ability to take another person’s perspective into account. In addition, we wanted to investigate whether adolescents and adults may differ on this task.

What would this correspond to in real life? Anna is seating in class trying to remember what the teacher said about tonight’s homework. At the same time her friend Sophie is talking to her about a common friend, Dana, who has a secret only Anna knows. In this situation, akin to multitasking,  Anna may forget the homework instruction or spill out Dana’s secret, because her working memory system has been overloaded.

Thirty-three female adolescents (11-17 years old) and 28 female adults (22-30 years old) took part in a variant of the Director task. Between each instruction given by the director, either one or three double-digits numbers were presented to the participants and they were asked to remember them.

Overall, adolescents were less accurate than adults on the number task and the Director task (combined, in a single “multitasking” measure) when they had to remember three numbers compared to one number. In addition, all participants were found to be slower to respond when the perspective of the director differed from their own and when their working memory was loaded with three numbers compared to one number, suggesting that multitasking may impact our social interactions.

Find out more

*Image caption: Presentation of multitasking paradigm (image published in Royal Society Open Science paper). For each trial, participants were first presented with either (a) one two-digit number (low load) or (b) three two-digit numbers (high load) for 3 s. Then participants were presented with the Director Task stimuli, which included a social (c) and non-social control condition (d). In this example, participants hear the instruction: ‘Move the large ball up’ in either a male or a female voice. If the voice is female, the correct object to move is the basketball, because in the DP condition the female director is standing in front of the shelves and can see all the objects, and in the DA condition, the absence of a red X on the grey box below the ‘F’ indicate that all objects can be moved by the participant. If the voice is male, the correct object to move is the football, because in the DP condition the male director is standing behind the shelves and therefore cannot see the larger basketball in the covered slot, and in the DA condition the red X over the grey box below the ‘M’ indicates that no objects in front of a grey background can be moved. After selecting an object in the Director Task, participants were presented with a display of two numbers, one of which corresponding to the only number (e) or one of the three numbers (f), shown to them at the beginning of the trial. Participants were instructed to click on the number they remembered being shown at the beginning of the trial.

. Reply . Category: Categories, Science . Tags: ,