Hindsight bias
Hindsight bias, or alternatively the knew-it-all-along effect and creeping determinism, is the inclination to see events that have already occurred as being more predictable than they were before they took place. It is a multifaceted phenomenon that can affect different stages of designs, processes, contexts, and situations. Hindsight bias may cause memory distortion, where the recollection and reconstruction of content can lead to false theoretical outcomes. It has been suggested that the effect can cause extreme methodological problems while trying to analyze, understand, and interpret results in experimental studies. A basic example of the hindsight bias is when, after viewing the outcome of a potentially unforeseeable event, a person believes he or she "knew it all along." Such examples are present in the writings of historians describing outcomes of battles, physicians recalling clinical trials, and in judicial systems trying to attribute responsibility and predictability of accidents.


The hindsight bias, although never referred to as such, was not a new concept when it emerged in psychological
Psychology is the study of the mind and behavior. Its immediate goal is to understand individuals and groups by both establishing general principles and researching specific cases. For many, the ultimate goal of psychology is to benefit society...

 research in the 1970s. In fact it had been indirectly described numerous times by historians, philosophers and physicians. In 1973 Baruch Fischoff attended a seminar where Paul Meehl stated an observation that clinicians often overestimate their ability to have foreseen the outcome of a particular case, as they claim to have known it all along. Baruch, a psychology graduate student at the time, saw an opportunity in psychological research to explain these observations.

In the early seventies investigation of heuristics and biases was a large area of study in psychology, led by Amos Tversky
Amos Tversky
Amos Nathan Tversky, was a cognitive and mathematical psychologist, a pioneer of cognitive science, a longtime collaborator of Daniel Kahneman, and a key figure in the discovery of systematic human cognitive bias and handling of risk. Much of his early work concerned the foundations of measurement...

 and Daniel Kahneman
Daniel Kahneman
Daniel Kahneman is an Israeli-American psychologist and Nobel laureate. He is notable for his work on the psychology of judgment and decision-making, behavioral economics and hedonic psychology....

. Two heuristic
Heuristic refers to experience-based techniques for problem solving, learning, and discovery. Heuristic methods are used to speed up the process of finding a satisfactory solution, where an exhaustive search is impractical...

s developed by Tversky and Kahneman were of immediate importance in the development of the hindsight bias, and these were the availability heuristic
Availability heuristic
The availability heuristic is a phenomenon in which people predict the frequency of an event, or a proportion within a population, based on how easily an example can be brought to mind....

 and the representativeness heuristic
Representativeness heuristic
The representativeness heuristic is a psychological term describing a phenomenon wherein people judge the probability or frequency of a hypothesis by considering how much the hypothesis resembles available data as opposed to using a Bayesian calculation. While often very useful in everyday life, it...

. In an elaboration of these heuristics, Beyth and Fischoff devised the first experiment directly testing the hindsight bias. They asked participants to judge the likelihood of several outcomes of U.S. President Richard Nixon
Richard Nixon
Richard Milhous Nixon was the 37th President of the United States, serving from 1969 to 1974. The only president to resign the office, Nixon had previously served as a US representative and senator from California and as the 36th Vice President of the United States from 1953 to 1961 under...

’s upcoming visit to Peking (also known as Beijing
Beijing , also known as Peking , is the capital of the People's Republic of China and one of the most populous cities in the world, with a population of 19,612,368 as of 2010. The city is the country's political, cultural, and educational center, and home to the headquarters for most of China's...

) and Moscow
Moscow is the capital, the most populous city, and the most populous federal subject of Russia. The city is a major political, economic, cultural, scientific, religious, financial, educational, and transportation centre of Russia and the continent...

. Some time after President Nixon’s return, participants were asked to recall, or reconstruct the probabilities they had assigned to each possible outcome, and their perceptions of likelihood of each outcome was greater or overestimated for events that actually had occurred. This study is frequently referred to in definitions of the hindsight bias, and the title of the paper, “I knew it would happen”, may have contributed to the hindsight bias being interchangeable with the term “knew it all along” hypothesis.

In 1975 Fischoff developed another method for investigating the hindsight bias, which at the time was referred to as the creeping determinism hypothesis. This method involves giving participants a short story with four possible outcomes, one of which they are told is true, and are then asked to assign the likelihood of each particular outcome. Participants frequently assign a higher likelihood of occurrence to whichever outcome they have been told is true. Remaining relatively unmodified, this method is still used in psychological and behavioural experiments investigating aspects of the hindsight bias. Having evolved from the heuristics of Tversky and Kahneman into the creeping determinism hypothesis and finally into the hindsight bias as we now know it, the concept has many practical applications and is still at the forefront of research today. Recent studies involving the hindsight bias have investigated the effect age has on the bias, how hindsight may impact interference and confusion, and how it may affect banking and investment strategies.


The hindsight bias is defined as a tendency to change an opinion from an original thought to something different because of newly provided information. Since 1973, when Fischhoff started the hindsight bias research, there has been a focus on two main explanations of the bias: distorted event probabilities and distorted memory for judgments of factual knowledge. In tests for hindsight bias a person is asked to remember a specific event from the past or recall some descriptive information that they had been tested on earlier. In between the first test and final test they are given the correct information about the event or knowledge. At the final test he or she will report that they knew the answer all along when they truly have changed their answer to fit with the correct information they were given after the initial test. Hindsight bias has been found to take place in both memory for experienced situations (events that the person is familiar with) and hypothetical situations (made up events where the person must imagine being involved). More recently it has been found that hindsight bias also exists in recall with visual material. When tested on initially blurry images the subjects learn what the true image was after the fact and they would then remember a clear recognizable picture.

Cognitive models

To understand how a person can so easily change the foundation of knowledge and belief for events after receiving new information three cognitive models of hindsight bias have been reviewed. The three models are SARA (Selective Activation and Reconstructive Anchoring), RAFT (Reconstruction After Feedback with Take the Best) and CMT (Causal Model Theory). SARA and RAFT focus on distortions or changes in a memory process while CMT focuses on probability judgments of hindsight bias.

The SARA model explains hindsight bias for descriptive information in memory and hypothetical situations and was created by Rüdiger Pohl and associates. SARA assumes that people have a set of images to draw their memories from. They suffer from the hindsight bias due to selective activation or biased sampling of that set of images. Basically, people only remember small select amounts of information and when asked to recall it at a later time they will use that biased image to support their own opinions about the situation. The set of images is originally processed in the brain when first experienced. When remembered this image is reactivated, and the ability for editing and alteration of the memory is possible which takes place in hindsight bias when new and correct information in presented. Leading one to believe that this new information when remembered at a later time is the persons original memory. Due to this reactivation in the brain a more permanent memory trace can be created. The new information acts as a memory anchor causing retrieval impairment.

The RAFT model explains hindsight bias with comparisons of objects using knowledge based probability
Probability is ordinarily used to describe an attitude of mind towards some proposition of whose truth we arenot certain. The proposition of interest is usually of the form "Will a specific event occur?" The attitude of mind is of the form "How certain are we that the event will occur?" The...

 then applying interpretations to those probabilities. When given two choices a person will recall the information on both topics and will make assumptions based on how reasonable they find the information to be. An example would be comparing two cities to find which is larger. If either city is well known (ie. popular sporting team) while the other is not as recognizable, the person’s mental cues for the more popular city will increase. They will then 'Take the best' option in their assessment of their own probabilities. They recognize a city due to a sports team then assume that the city will be the most populated. Take the Best refers to a cue that is viewed as most valid and becomes support for the person’s interpretations. RAFT is a by-product of adaptive learning
Adaptive learning
Adaptive learning is an educational method which uses computers as interactive teaching devices. Computers adapt the presentation of educational material according to students' weaknesses, as indicated by their responses to questions. The motivation is to allow electronic education to incorporate...

. Feedback information will update a person's knowledge base. This can lead to a person who is unable to retrieve the initial information since the information cue has been replaced by a cue that they thought was more fitting. The 'best' cue has been replaced and the person only remembers the answer that is most likely and believes that they thought this was the best point the whole time.

Both SARA and RAFT descriptions include a memory trace impairment or cognitive distortion
Cognitive distortion
Cognitive distortions are exaggerated and irrational thoughts identified in cognitive therapy and its variants, which in theory perpetuate certain psychological disorders. The theory of cognitive distortions was first proposed by Aaron T. Beck. Eliminating these distortions and negative thoughts is...

 that is caused by feedback of information and reconstruction of memory.

CMT is a non-formal theory based on work by many researchers to create a collaborative process model for hindsight bias that involves event outcomes. People try to make sense of an event that has not turned out how they expected by creating causal reasoning for the starting event conditions. This can give that person the idea that the event outcome was inevitable and there was nothing that could take place to prevent it from happening. CMT can be caused by a discrepancy between a person’s expectation of the event and the reality of an outcome. They consciously want to make sense of what has happened and selectively retrieve memory that supports the current outcome. The causal attribution can be motivated by wanting to feel more positive about the outcome and possibly themselves.

Are people liars or are they tricking themselves into believing that they knew the right answer? These models would show that memory distortions and personal bias play a role.

Memory distortions

Hindsight bias has similarities to other memory distortions such as misinformation effect
Misinformation effect
The misinformation effect refers to the finding that exposure to misleading information presented between the encoding of an event and its subsequent recall causes impairment in memory. This effect occurs when participants' recall of an event they witnessed is altered by introducing misleading...

 and false autobiographical memory. Misinformation effect occurs after an event is witnessed; new information received after the fact influences how the person remembers the event, and can be called post-event misinformation. This is an important issue with eyewitness testimony
Eyewitness testimony
Research in eyewitness testimony is mostly considered a subfield within legal psychology, however it is a field with very broad implications. Human reports are normally based on visual perception, which is generally held to be very reliable...

. False autobiographical memory
Autobiographical memory
Autobiographical memory is a memory system consisting of episodes recollected from an individual's life, based on a combination of episodic and semantic memory.-Formation:Conway and Pleydell-Pearce proposed that autobiographical...

 takes place when suggestions or additional outside information is provided to distort and change memory of events; this can also lead to false memory syndrome. At times this can lead to creation of new memories that are completely false and have not taken place. All three of these memory distortions contain a three-stage procedure. The details of each procedure are different but can result in some psychological manipulation
Psychological manipulation
Psychological manipulation is a type of social influence that aims to change the perception or behavior of others through underhanded, deceptive, or even abusive tactics. By advancing the interests of the manipulator, often at the other's expense, such methods could be considered exploitative,...

 and alteration of memory. Stage one is different between the three paradigm
The word paradigm has been used in science to describe distinct concepts. It comes from Greek "παράδειγμα" , "pattern, example, sample" from the verb "παραδείκνυμι" , "exhibit, represent, expose" and that from "παρά" , "beside, beyond" + "δείκνυμι" , "to show, to point out".The original Greek...

s although all involve an event, an event that has taken place (misinformation effect), an event that has not taken place (false autobiographical memory), and a judgment made by a person about an event that must be remembered (hindsight bias). Stage two consists of more information that is received by the person after the event has taken place. The new information given in hindsight bias is correct and presented up front to the person, while the extra information for the other two memory distortions is wrong and presented in a indirect and possibly manipulative way. The third stage consists of recalling the starting information. The person must recall the original information with hindsight bias and misinformation effect while a person that has a false autobiographical memory is expected to remember the incorrect information as a true memory.

For a false autobiographical memory to be created, the person must believe a memory that is not real. To seem real, the information given must be influenced by their own personal judgments. There is no real episode of an event to remember, so this memory construction must be logical to that person's knowledge base. Hindsight bias and misinformation effect recall a specific time and event, this is called an episodic memory
Episodic memory
Episodic memory is the memory of autobiographical events that can be explicitly stated. Semantic and episodic memory together make up the category of declarative memory, which is one of the two major divisions in memory...

 processes. These two memory distortions both use memory-based mechanisms that involve a memory trace that has been changed. Hippocampus
The hippocampus is a major component of the brains of humans and other vertebrates. It belongs to the limbic system and plays important roles in the consolidation of information from short-term memory to long-term memory and spatial navigation. Humans and other mammals have two hippocampi, one in...

 activation takes place when an episodic memory is recalled. The memory is then available for alteration by new information. The person believes that the remembered information is the original memory trace, not an altered memory. This new memory is made from accurate information and therefore the person does not have much motivation to admit they were wrong originally by remembering the original memory. This can lead to motivated forgetting
Motivated forgetting
Motivated forgetting is a debated concept referring to a psychological defence mechanism in which people forget unwanted memories, either consciously or unconsciously. There are times when memories are reminders of unpleasant experiences that make people angry, sad, anxious, ashamed or afraid...


Motivated forgetting

Following a negative outcome of a situation people do not want to accept blame
Blame is the act of censuring, holding responsible, making negative statements about an individual or group that their action or actions are socially or morally irresponsible, the opposite of praise. When someone is morally responsible for doing something wrong their action is blameworthy...

. Instead of accepting their role in the event, they view themselves as caught up in a situation that was unforeseeable and therefore they are not the culprit, which is referred to as defensive processing, or view the situation as inevitable and there was nothing that could be done to prevent it which is retroactive pessimism. Defensive processing involves less hindsight bias as they are playing ignorant on the event. Retroactive pessimism makes use of hindsight bias after a negative, unwanted outcome. Events in life can be hard to control or predict. It is no surprise that people want to view themselves in a more positive light and not take responsibility for situations they could have altered. This leads to hindsight bias in the form of retroactive pessimism to inhibit upward counterfactual thinking
Counterfactual thinking
Counterfactual thinking is a term of psychology that describes the tendency people have to imagine alternatives to reality. Humans are predisposed to think about how things could have turned out differently if only..., and also to imagine what if?....

 to succumb to an inevitable fate. This memory inhibition
Memory inhibition
In psychology, memory inhibition is the ability not to remember irrelevant information. Memory inhibition is a critical component of an effective memory system. For example, imagine if, when a person tried to remember where he had parked his car, every place he had ever parked his car came to mind;...

, preventing a person from recalling what really happened may lead to failure to accept one's mistakes and therefore unable to learn and grow to prevent a similar mistake from taking place in the future. Hindsight bias can also lead to overconfidence in one's decisions without considering other options. They see themselves as a person who remembers correctly, even though they are just forgetting that they were wrong. Avoiding responsibility is common among the human population. Examples will be discussed below to show the regularity and severity of hindsight bias in society.


Research shows that people still exhibit the bias even when they are informed about it. Researchers attempt to decrease the bias in participants has failed, leading one to think that hindsight bias has an automatic source in cognitive reconstruction. This supports the Causal Model Theory and the use of sense-making to understand event outcomes. The only observable way to decrease hindsight bias in testing is to increase accountability of the participant's answer.


Schizophrenia is a mental disorder characterized by a disintegration of thought processes and of emotional responsiveness. It most commonly manifests itself as auditory hallucinations, paranoid or bizarre delusions, or disorganized speech and thinking, and it is accompanied by significant social...

 is an example of a disorder that directly affects the hindsight bias. The hindsight bias has a stronger effect on schizophrenic individuals compared to individuals from the general public.

The hindsight bias effect is a paradigm that demonstrates how recently acquired knowledge influences the recollection of past information. Recently acquired knowledge has a strange, but strong influence on schizophrenic individuals in relation to information previous learned. New information combined with the lack of acceptable influence of past reality-based memories can disconfirm behaviour and delusional belief, which typify in patients suffering from schizophrenia. This can cause faulty memory, which can lead to hindsight thinking and believing in knowing something they don't. Delusion-prone individuals suffering from schizophrenia can falsely jump to conclusions . Jumping to conclusions can lead to hindsight, which strongly influences the delusional conviction in schizophrenic individuals. In numerous studies, cognitive functional deficits in schizophrenic individuals impair their ability represent and uphold contextual processing.

Post-traumatic stress disorder

Post-traumatic stress disorder
Post-traumatic stress disorder
Posttraumaticstress disorder is a severe anxiety disorder that can develop after exposure to any event that results in psychological trauma. This event may involve the threat of death to oneself or to someone else, or to one's own or someone else's physical, sexual, or psychological integrity,...

 is the re-experiencing and avoidance of trauma-related stressors, emotions and memories from a past event or events that has cognitive dramatizing impact on an individual.

PTSD can be attributed to the functional impairment of the prefrontal cortex
Prefrontal cortex
The prefrontal cortex is the anterior part of the frontal lobes of the brain, lying in front of the motor and premotor areas.This brain region has been implicated in planning complex cognitive behaviors, personality expression, decision making and moderating correct social behavior...

 (PFC) structure. Dysfunctions of cognitive processing of context and abnormalities that PTSD patients suffer from can affect hindsight thinking such as in combat soldiers perceiving they could have altered outcomes of events in war. The Prefrontal Cortex (PFC) and dopamine
Dopamine is a catecholamine neurotransmitter present in a wide variety of animals, including both vertebrates and invertebrates. In the brain, this substituted phenethylamine functions as a neurotransmitter, activating the five known types of dopamine receptors—D1, D2, D3, D4, and D5—and their...

 (DA) systems are parts of the brain that can be responsible for the impairment in cognitive control processing of context information. The PFC is well-known for controlling the thought process in hindsight bias that something will happen when it evidently does not. Brain impairment in certain brain regions can also affect the thought process of an individual who may engage in hindsight thinking.

Cognitive flashbacks and other associated features from a traumatic event can trigger severe stress and negative emotions such as unpardonable guilt. For example, studies were done on trauma-related guilt characteristics of war veterans with chronic PTSD 8. Although there has been limited research, significant data proves that hindsight bias, in terms of guilt and responsibility from traumatic events of war, has an effect on war veteran’s personal events of wrongdoing. They blame themselves and in hindsight, perceive that they could have prevented what happened.

Health care system

Accidents are prone to happen in any human
Humans are the only living species in the Homo genus...

 undertaking, but accidents occurring within the health care
Health care
Health care is the diagnosis, treatment, and prevention of disease, illness, injury, and other physical and mental impairments in humans. Health care is delivered by practitioners in medicine, chiropractic, dentistry, nursing, pharmacy, allied health, and other care providers...

 system seem more salient and severe due to their profound effect on the lives of those involved, sometimes resulting in the death of a patient. Hindsight bias has been shown to be a disadvantage of nearly all methods of measuring error and adverse events within the healthcare system. These methods include morbidity and mortality conferences and autopsy
An autopsy—also known as a post-mortem examination, necropsy , autopsia cadaverum, or obduction—is a highly specialized surgical procedure that consists of a thorough examination of a corpse to determine the cause and manner of death and to evaluate any disease or injury that may be present...

, case analysis, medical malpractice
Medical malpractice
Medical malpractice is professional negligence by act or omission by a health care provider in which the treatment provided falls below the accepted standard of practice in the medical community and causes injury or death to the patient, with most cases involving medical error. Standards and...

 claims analysis, staff interviews and even patient observation. Furthermore, studies of injury or death rates as a result of error and virtually all incident review procedures used in healthcare today fail to control for hindsight bias, severely limiting the generalizability and integrity of the research. Physician
A physician is a health care provider who practices the profession of medicine, which is concerned with promoting, maintaining or restoring human health through the study, diagnosis, and treatment of disease, injury and other physical and mental impairments...

s who are primed with a possible diagnosis before evaluating the symptoms of a patient themselves are more likely to arrive at the primed diagnosis than physicians who were only given the symptoms of the patient. According to Harvard Medical Practice Studies, 44,000–98,000 deaths in the United States
United States
The United States of America is a federal constitutional republic comprising fifty states and a federal district...

 each year are a result of safety incidents within the healthcare system. Many of these deaths are viewed to be preventable after the fact, clearly indicating the presence and importance of a hindsight bias in this field.

Judicial system

Hindsight bias results in being held to a higher standard in court
A court is a form of tribunal, often a governmental institution, with the authority to adjudicate legal disputes between parties and carry out the administration of justice in civil, criminal, and administrative matters in accordance with the rule of law...

. The defense is particularly susceptible to these effects since their actions are the ones being scrutinized by the jury
A jury is a sworn body of people convened to render an impartial verdict officially submitted to them by a court, or to set a penalty or judgment. Modern juries tend to be found in courts to ascertain the guilt, or lack thereof, in a crime. In Anglophone jurisdictions, the verdict may be guilty,...

. Due to the hindsight bias, defendant
A defendant or defender is any party who is required to answer the complaint of a plaintiff or pursuer in a civil lawsuit before a court, or any party who has been formally charged or accused of violating a criminal statute...

s will be judged as being capable of preventing the bad outcome. Though much stronger for the defendants, hindsight bias also affects the plaintiff
A plaintiff , also known as a claimant or complainant, is the term used in some jurisdictions for the party who initiates a lawsuit before a court...

s. In cases where there is an assumption of risk, hindsight bias may contribute to the jurors perceiving the event as riskier due to the poor outcome. This may lead the jury to feel that the plaintiff should have exercised greater caution in the situation. Both of these effects can be minimized if attorneys put the jury in a position of foresight
Foresight (psychology)
Foresight is the ability to predict, or the action of predicting, what will happen or what is needed in the future.Studies suggest that much of human daily thought is directed towards potential future events. Because of this and its role in human control on the planet, the nature and evolution of...

 rather than hindsight through the use of language and timelines. Encouraging people to explicitly think about the counterfactuals was an effective means of reducing the hindsight bias. In other words, people became less attached to the actual outcome and were more open to consider alternative lines of reasoning prior to the event. Judge
A judge is a person who presides over court proceedings, either alone or as part of a panel of judges. The powers, functions, method of appointment, discipline, and training of judges vary widely across different jurisdictions. The judge is supposed to conduct the trial impartially and in an open...

s involved in fraudulent transfer litigation cases were subject to the hindsight bias as well, resulting in an unfair advantage for the plaintiff. This shows that jurors are not the only ones sensitive to the effects of the hindsight bias in the courtroom.

See also

  • Availability heuristic
    Availability heuristic
    The availability heuristic is a phenomenon in which people predict the frequency of an event, or a proportion within a population, based on how easily an example can be brought to mind....

  • Causal attribution
  • Counterfactual thinking
    Counterfactual thinking
    Counterfactual thinking is a term of psychology that describes the tendency people have to imagine alternatives to reality. Humans are predisposed to think about how things could have turned out differently if only..., and also to imagine what if?....

  • False memory syndrome
  • Misinformation effect
    Misinformation effect
    The misinformation effect refers to the finding that exposure to misleading information presented between the encoding of an event and its subsequent recall causes impairment in memory. This effect occurs when participants' recall of an event they witnessed is altered by introducing misleading...

  • Representativeness heuristic
    Representativeness heuristic
    The representativeness heuristic is a psychological term describing a phenomenon wherein people judge the probability or frequency of a hypothesis by considering how much the hypothesis resembles available data as opposed to using a Bayesian calculation. While often very useful in everyday life, it...

  • Motivated forgetting
    Motivated forgetting
    Motivated forgetting is a debated concept referring to a psychological defence mechanism in which people forget unwanted memories, either consciously or unconsciously. There are times when memories are reminders of unpleasant experiences that make people angry, sad, anxious, ashamed or afraid...

External links

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