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Concept: Pessimism


Received academic wisdom holds that human judgment is characterized by unrealistic optimism, the tendency to underestimate the likelihood of negative events and overestimate the likelihood of positive events. With recent questions being raised over the degree to which the majority of this research genuinely demonstrates optimism, attention to possible mechanisms generating such a bias becomes ever more important. 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.

Concepts: Scientific method, Psychology, Critical thinking, Statistics, Motivation, Philosophy of life, Optimism, Pessimism


Depressive disorder is often associated with cognitive biases. In this study, we took a unique opportunity to investigate whether trait pessimism could predict vulnerability to stress-induced anhedonia in an animal model of depression. In a series of ambiguous-cue interpretation (ACI) tests, we identified animals displaying ‘pessimistic’ and ‘optimistic’ traits. Subsequently, the rats were subjected to chronic restraint, and the trait differences in response to stress were investigated using sucrose preference and ACI tests before, during and after the stress regime. Although stress resulted in anhedonia in both subgroups, it occurred faster and lasted longer in the ‘pessimistic’ compared to the ‘optimistic’ animals. Chronic stress exposure also increased the negative judgment bias in rats, although this effect was not dependent on the ‘pessimistic’ trait. For the first time, we demonstrated a link between cognitive judgment bias and vulnerability to stress-induced anhedonia in an animal model. We also introduced a cognitive biomarker, which may be of value for etiological depression studies.Neuropsychopharmacology accepted article preview online, 10 May 2013; doi:10.1038/npp.2013.116.

Concepts: Cognitive bias, Motivation, Major depressive disorder, Mood disorder, Dysthymia, Bias, Optimism, Pessimism


The present research examined whether the tendency to brace for the worst by becoming pessimistic as news approaches varies across people, namely people who differ in their trait-like outlooks on the future (dispositional optimism, defensive pessimism).

Concepts: Present, Time, Future, Motivation, Past, Optimism, Pessimism, Is the glass half empty or half full?


Recent advances in animal welfare science used judgement bias, a type of cognitive bias, as a means to objectively measure an animal’s affective state. It is postulated that animals showing heightened expectation of positive outcomes may be categorised optimistic, while those showing heightened expectations of negative outcomes may be considered pessimistic. This study pioneers the use of a portable, automated apparatus to train and test the judgement bias of dogs. Dogs were trained in a discrimination task in which they learned to touch a target after a tone associated with a lactose-free milk reward and abstain from touching the target after a tone associated with water. Their judgement bias was then probed by presenting tones between those learned in the discrimination task and measuring their latency to respond by touching the target. A Cox’s Proportional Hazards model was used to analyse censored response latency data. Dog and Cue both had a highly significant effect on latency and risk of touching a target. This indicates that judgement bias both exists in dogs and differs between dogs. Test number also had a significant effect, indicating that dogs were less likely to touch the target over successive tests. Detailed examination of the response latencies revealed tipping points where average latency increased by 100% or more, giving an indication of where dogs began to treat ambiguous cues as predicting more negative outcomes than positive ones. Variability scores were calculated to provide an index of optimism using average latency and standard deviation at cues after the tipping point. The use of a mathematical approach to assessing judgement bias data in animal studies offers a more detailed interpretation than traditional statistical analyses. This study provides proof of concept for the use of an automated apparatus for measuring cognitive bias in dogs.

Concepts: Critical thinking, Statistics, Cognitive psychology, Somatosensory system, Arithmetic mean, Dog, Optimism, Pessimism


Optimism is a cognitive construct (expectancies regarding future outcomes) that also relates to motivation: optimistic people exert effort, whereas pessimistic people disengage from effort. Study of optimism began largely in health contexts, finding positive associations between optimism and markers of better psychological and physical health. Physical health effects likely occur through differences in both health-promoting behaviors and physiological concomitants of coping. Recently, the scientific study of optimism has extended to the realm of social relations: new evidence indicates that optimists have better social connections, partly because they work harder at them. In this review, we examine the myriad ways this trait can benefit an individual, and our current understanding of the biological basis of optimism.

Concepts: Psychology, Sociology, Behavior, Motivation, Human behavior, Optimism, Pessimism, Is the glass half empty or half full?


Optimism and pessimism are associated with important outcomes including health and depression. Yet it is unclear if these apparent polar opposites form a single dimension or reflect two distinct systems. The extent to which personality accounts for differences in optimism/pessimism is also controversial. Here, we addressed these questions in a genetically informative sample of 852 pairs of twins. Distinct genetic influences on optimism and pessimism were found. Significant family-level environment effects also emerged, accounting for much of the negative relationship between optimism and pessimism, as well as a link to neuroticism. A general positive genetics factor exerted significant links among both personality and life-orientation traits. Both optimism bias and pessimism also showed genetic variance distinct from all effects of personality, and from each other.

Concepts: DNA, Genetics, Gregor Mendel, Motivation, Heritability, Optimism, Pessimism, Is the glass half empty or half full?


Extinction of learning is a common, yet under-reported limitation of judgment bias testing methods Repeated exposure to the ambiguous probe of a judgment bias paradigm encourages the animal to cease display of the required behaviours. However, there remains a need to repeatedly test animals to achieve statistical power. A delicate balance therefore needs to be struck between over- and under-exposure of the animals to the test conditions. This study presents the data of rats, a common animal subject of judgment bias testing. Rats were exposed to the ambiguous probe of a common, active-choice judgment bias test for 11 consecutive days. There was a significant increase in the latency to respond to the ambiguous probe following day 8, with no significant increase experienced for either the positive or less-positive probes. Following day 8 there was a significant increase in both optimistic and pessimistic latencies in response to the ambiguous probe. Therefore, repeated exposure to the ambiguous probe caused an increased latency in response even though optimistic interpretations were recorded. This implies that the use of response latency alone as a measure in judgment bias testing can falsely identify pessimism. Researchers should modify experimental design to include both choice and latency measures.

Concepts: Psychology, Animal, The Animals, Test method, Motivation, Optimism, Pessimism, Is the glass half empty or half full?


Investigate the relationship between optimism and pessimism and the cortisol awakening response (CAR) and past life review in healthy older people.

Concepts: Death, Cortisol, Motivation, Philosophy of life, Optimism, Pessimism, Is the glass half empty or half full?


This study aims to understand the role that optimism could play in the context of a health asset approach to promote adolescent health-related quality of life (HRQOL). Adolescents (n = 948), between 11 and 16 years old from a medium-sized rural town in Sweden, answered questionnaires measuring optimism, pessimism, and HRQOL. The findings indicate a significant decrease in optimism and a significant increase in pessimism between early and midadolescence. The study has allowed us to present associational evidence of the links between optimism and HRQOL. This infers the potential of an optimistic orientation about the future to function as a health asset during adolescence and by implication may provide additional intervention tool in the planning of health promotion strategies.

Concepts: Future, Quality, Adolescence, Motivation, Gross domestic product, Optimism, Pessimism, Is the glass half empty or half full?


In the present study, we have investigated the effects of the traits ‘optimism’ and ‘pessimism’ on cognitive flexibility in an animal model of depression based on chronic restraint stress. For this, first, we trained and tested the rats in a series of ambiguous-cue interpretation (ACI) tests, which allowed us to classify them as ‘optimistic’ or ‘pessimistic’. Subsequently, we re-trained and re-tested the animals in the Attentional Set Shifting Task (ASST), which allowed evaluation of the differences between ‘optimists’ and ‘pessimists’ in terms of cognitive flexibility. Finally, we subjected half of the ‘optimistic’ and half of the ‘pessimistic’ rats to chronic (2 weeks) restraint stress and assessed the interaction between cognitive judgement bias and stress in the ASST. Although we did not observe statistically significant effects of the investigated traits and stress on cognitive flexibility, the ‘pessimistic’ animals subjected to chronic restraint stress showed significantly longer latencies to approach experimental rewards than their ‘optimistic’ conspecifics. This effect may indicate a stress-induced motivational deficit that is specific to ‘pessimistic’ animals. The results of the present study, along with our previous reports, indicate that the trait ‘pessimism’ determines animals' vulnerability to stress.

Concepts: Statistical significance, The Animals, Motivation, Philosophy of life, Optimism, Pessimism, Is the glass half empty or half full?, Nihilism