Hindsight bias, also known as the knew-it-all-along effect or 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 not hitherto named as such, was not a new concept when it emerged in psychological research in the 1970s. In fact it had been indirectly described numerous times by historians, philosophers and physicians. In 1973 Baruch Fischhoff attended a seminar where Paul E. 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 and Daniel Kahneman. Two heuristics identified by Tversky and Kahneman were of immediate importance in the development of the hindsight bias, and these were the availability heuristic and the representativeness heuristic. In an elaboration of these heuristics, Beyth and Fischhoff 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’s upcoming visit to Peking (now romanized as Beijing) and Moscow. 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 phrase "knew it all along" hypothesis.
In 1975 Fischhoff 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.
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The hindsight bias is defined as a tendency to change a recollection 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. The role of surprise can help explain the malleability of hindsight bias. There are three ways in which surprise influences the reconstruction of pre-outcome predictions: (1) Surprise is used as a direct metacognitive heuristic to estimate the distance between outcome and prediction, (2) surprise triggers a deliberate sense-making process, and (3) it also biases this process by enhancing the retrieval of surprise-congruent information and expectancy-based hypothesis testing.  Along with the emotion of surprise, personality traits affect hindsight bias. A new integrative lens model is an approach to figure out the bias and accuracy in human inferences due to their individual personality traits. This model integrates on accurate personality judgments and hindsight effects as a by-product of knowledge updating. During the study, there were three processes that had the potential to explain the occurrence of hindsight effects in personality judgments. Those three processes are changes in an individual’s cue perceptions, changes in the utilization of more valid cues, and changes in consistency with which the cue knowledge is applied. After two studies, it was clear that there were hindsight effects for all five personality dimensions. Evidence was found that both the utilization of more valid cues and changes in cue perceptions, but not changes in the consistency with which cue knowledge is applied account for the hindsight effects. During both studies, participants were presented with target pictures and were asked to judge each target’s levels of the Big Five. The Big Five represents all five personality dimensions.  Another topic that affects the function of hindsight bias is the auditory function of humans. To test the affects of auditory distractions on hindsight bias, four experiments were completed. Experiment one included plain words, experiment two included words with warning, experiment three included full sentences, and experiment our included less-degraded words. By using these different techniques, it offers a different range of detection. By knowing the identities of words caused people to overestimate others’ naïve ability to identify moderately to highly degraded spoken versions of those words. People who know the outcome of an event tend to overestimate their own prior knowledge or others’ naïve knowledge of the event. Speakers tend to overestimate the clarity of their message while listeners overestimate their understanding of communication. This hindsight bias creates a feeling of inevitability. This auditory hindsight bias occurs despite people’s effort to avoid it.  Not only do hindsight bias affect adults, but also children. Hindsight bias in adults and in children shares a core cognitive constraint. That constraint is a tendency to be biased on one’s current knowledge when attempting to recall or reason about a more naïve cognitive state, regardless of whether that more naïve state is one’s own earlier naïve state or someone else’s. Children have a theory of mind, which is their mental state of reasoning. Hindsight bias is a fundamental problem in cognitive perspective taking. After reviewing developmental literature on hindsight bias and other limitations, it was found that some of children’s limitation in the theory of mine may stem from the same core component as hindsight bias. This key factor brings forth underlying mechanisms. A developmental approach is necessary for a comprehensive understanding of the nature of hindsight bias in social cognition. 
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 is 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 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 (i.e. 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. 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 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 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. False autobiographical memory 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 and alteration of memory. Stage one is different between the three paradigms 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 an 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 process. These two memory distortions both use memory-based mechanisms that involve a memory trace that has been changed. Hippocampus 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 
Following a negative outcome of a situation, people do not want to accept blame. 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 that 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 of 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 do not want to take responsibility for situations they could have altered. This leads to hindsight bias in the form of retroactive pessimism to inhibit upward counterfactual thinking, instead interpreting the outcome as succumbing to an inevitable fate. This memory inhibition, preventing a person from recalling what really happened, may lead to failure to accept one's mistakes and therefore to be 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. Such people see themselves as persons who remember 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.[vague]
Related disorders 
Schizophrenia 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 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 (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 (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 suggests that hindsight bias, in terms of guilt and responsibility from traumatic events of war, has an effect on war veterans' personal perception 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 undertaking, but accidents occurring within the health care 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, case analysis, medical malpractice 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. Physicians 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 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. The defense is particularly susceptible to these effects since their actions are the ones being scrutinized by the jury. Due to the hindsight bias, defendants will be judged as being capable of preventing the bad outcome. Though much stronger for the defendants, hindsight bias also affects the plaintiffs. 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 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. Judges 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
- Causal attribution
- Counterfactual thinking
- False memory syndrome
- Misinformation effect
- Representativeness heuristic
- Motivated forgetting
- Memory conformity
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