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Optimism bias

Optimism bias is a science topic covered in the lgStudy science library. This page brings together a partial reference excerpt, illustrations, worked examples, real-world applications and a short study plan, so you can understand Optimism bias rather than just read about it. In short: Optimism bias is the tendency of an individual to overestimate the likelihood of positive events and underestimate that of negative events. A cognitive bias, the optimistic bias is common across cultures, genders, ethnicities, nationalities, and age groups.

Key takeaways

  • Optimism bias belongs to science; place it in that map before memorising details.
  • Learn the definition first, then one example that makes the definition concrete.
  • Connect Optimism bias to a quantity you can measure, compute or draw — that is where exam questions come from.
  • Reproduce the core statement of Optimism bias from memory before moving on to harder problems.

Reference excerpt

Optimism bias is the tendency of an individual to overestimate the likelihood of positive events and underestimate that of negative events. A cognitive bias, the optimistic bias is common across cultures, genders, ethnicities, nationalities, and age groups. It has implications to individual and group decision making, public health, policy, economics, and law. The extent of optimism bias depends on a person's overall mood, their desired end state, the information they have about themselves and others, and their cognitive mechanisms. Generally, the optimism bias is stronger for underestimating negative events than overestimating positive events. It is also known as unrealistic optimism, comparative optimism, and optimist's delusion.

Operationalisation, methodology, and theory Optimism bias is typically measured through two determinants of risk: absolute risk, where individuals are asked to estimate their likelihood of experiencing a negative event, and comparative risk, where individuals are asked to estimate the likelihood of experiencing a negative event compared to others of the same age and sex. Problems can occur when trying to measure absolute risk, because it is difficult to determine the actual risk statistic for a person and compare it against their personal estimate. Direct comparisons ask whether an individual's own risk of experiencing an event is less than, greater than, or equal to someone else's risk. Indirect comparisons ask individuals to provide separate estimates of their own risk and that of others in experiencing the same event. After obtaining scores, researchers use the information to determine if there is a difference in the average risk estimate of the individual compared to the average risk estimate of their peers. Generally, in negative events, the mean risk of an individual appears lower than the risk estimate of others. This is then used to demonstrate the bias' effect. Optimistic bias can only be defined and measured at a group level, because at an individual level the positive assessment could be true. Likewise, difficulties can arise in measurement procedures, as it is difficult to determine when someone is being optimistic, realistic, or pessimistic. Research suggests that the bias comes from an overestimate of group risks rather than underestimating one's own risk.

Valence effects The valence effect refers to the influence of positive or negative framing on unrealistic optimism. Since 2003, Ron S. Gold and colleagues have studied this phenomenon by presenting the same event in different ways. For example, some participants receive information about conditions that promote a health-related event, such as developing heart disease, and are asked to rate the likelihood of experiencing it. Others receive matched information about conditions that prevent the same event and are asked to rate the likelihood of avoiding it. Their findings consistently show that unrealistic optimism is greater when events are framed with negative valence than with positive valence.

Neuroscience Functional neuroimaging suggests a key role for the rostral Anterior Cingulate Cortex (ACC) in modulating both emotional processing and autobiographical retrieval. It is part of brain network showing extensive correlation between rostral ACC and amygdala during imagining of future positive events and restricted correlation during imagining of future negative events. Based on these data, it is suggested that the rostral ACC has a crucial part to play in creating positive images of the future and ultimately, in ensuring and maintaining the optimism bias. It has also been reported in other animals, such as rats and birds.

Controlling factors Factors leading to the optimistic bias can be categorized into four different groups: desired end states of comparative judgment; cognitive mechanisms; information about the self versus a target; and underlying affect.

Desired end states of comparative judgment Many explanations for the optimistic bias come from the goals that people want and outcomes they wish to see.

Self-enhancement Self-enhancement theories suggest that optimistic predictions are satisfying, that it feels good to think that positive events will happen, and that people can control their anxiety and other negative emotions if they believe they are better off than others. As such, the theory predicts that people tend to focus on finding information that supports what they want to see happen. This also suggests that people might lower their risks compared to others to make themselves look better than average, a form of self-presentation.

Self-presentation Self-presentation theories suggest that people unconsciously attempt to establish and maintain a desired personal image in social situations, and that the optimistic bias is a representative of self-presentational processes. Studies also suggest that individuals who present themselves in a pessimistic and more negative light are generally less accepted by the rest of society.

Personal control/perceived control People tend to be more optimistically biased when they believe they have more control over events than others. Studies have suggested that the greater perceived control someone has, the greater their optimistic bias. Stemming from this, control is a stronger factor when it comes to personal risk assessments, but not when assessing others. The relationship between the optimistic bias and perceived control is moderated by a number of factors, such as nationality, age, occupation, research methodology, and situation. An opposing factor to perceived control is prior experience. Prior experience is typically associated with less optimistic bias; some studies suggest this is from a decrease in the perception of personal control, or by making it easier for individuals to imagine themselves at risk. In public health and safety contexts, people are more likely to think that they will not be harmed in a car accident if they are driving the vehicle. Someone believes that they have a lot of control over becoming infected with HIV, they are more likely to view their risk of contracting the disease to be low.

Cognitive mechanisms The optimistic bias is possibly also influenced by cognitive mechanisms that guide judgments and decision-making processes.

… excerpt ends here. Continue reading the full article.

Worked examples

Example 1 — a first encounter with Optimism bias

Start with the simplest possible case. Write down what Optimism bias claims or describes in one sentence, then invent the smallest concrete situation in which that sentence is true. In science, the smallest case is usually a single object, a single equation or a single measurement. Check that every symbol or term in your sentence has a meaning in that case.

Example 2 — changing one variable

Take the situation from Example 1 and change exactly one quantity: double it, halve it, or set it to zero. Predict what should happen to Optimism bias before you calculate. Comparing your prediction with the result is the fastest way to find out whether you understand the idea or only the words.

Example 3 — an exam-style question

Typical questions about Optimism bias ask you to (a) state it precisely, (b) apply it to given data, and (c) explain a limitation. Practise writing all three answers in under five minutes; the third part is what separates a full-mark answer from an average one.

Applications of Optimism bias

In research
Optimism bias appears in science research whenever the underlying quantities have to be modelled precisely. Papers usually cite it as a starting assumption and then explore where it breaks down.
In technology and industry
Engineering practice reuses Optimism bias in design rules, simulations and safety margins. Knowing the idea lets you read a specification sheet and understand why the numbers look the way they do.
In the classroom
Optimism bias is common in secondary-school and first-year university syllabi. It links to neighbouring topics Cognitive biases, Forecasting, Optimism, so understanding it makes those chapters shorter.
In everyday life
Look for Optimism bias outside the textbook — in sport, cooking, traffic, electronics or the sky above you. An example you found yourself is remembered far longer than one you were given.
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How to study Optimism bias in 20 minutes

  1. Read the reference excerpt below once, without taking notes.
  2. Close the page and write down what Optimism bias means in your own words.
  3. Compare your version with the excerpt and mark what you missed.
  4. Work through the three examples above with pen and paper.
  5. Explain Optimism bias out loud to somebody else — or to Teacher Smith in the lgStudy chat.

Frequently asked questions

What is Optimism bias in simple terms?

Optimism bias is the tendency of an individual to overestimate the likelihood of positive events and underestimate that of negative events. A cognitive bias, the optimistic bias is common across cultures, genders, ethnicities, nationalities, and age groups.

Why does Optimism bias matter?

Because it connects several science ideas at once: it gives you a definition you can apply, a quantity you can calculate, and a way to check whether a result is plausible.

How should I study Optimism bias?

Read the excerpt, restate it from memory, then work through the examples and applications listed on this page. The five-step study plan above takes about twenty minutes.

What does this page cover?

It gives you a compact reference excerpt plus original lgStudy explanations, examples, applications and study material on Optimism bias.

Tags

  • Cognitive biases
  • Forecasting
  • Optimism
  • Social psychology

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