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Explain one bias in thinking and decision-making with reference to one research study. (9)Confirmation bias is defined as the tendency to search for, interpret, favour, and recall information or evidence that substantiates one's pre-existing beliefs or hypotheses and this thinking bias can lead to poor decision-making. For example, we meet a man who says he is a mathematician. Due to our schema of stored knowledge about mathematicians, in general, we expect the man will be rather unemotional, lacking in social skills and have a strange sense of humour. Having spoken with him we may remember things that he said that confirm our beliefs, e.g. he was rather quiet and failed to laugh when I made a joke and we ignore information that contrasts with expectation, e.g. he spoke warmly about his daughter and maintained good eye contact. Unfortunately, this style of thinking may lead us to draw unhelpful conclusions, such that we do not seek out this man in future and miss out on a potential interesting new friend. This thinking strategy may have evolved to help us cope with the intensity and sheer volume of information received through the senses. In order to cope with this flood of incoming data, humans instinctively deploy ‘system one’ thinking, (Stanowich and West 2000) which is fast and occurs without conscious awareness. As we have no control over this style of thinking, we may be ‘forced’ to ignore information that does not fit with prior knowledge. Instead we focus on a limited array of details which we use to confirm our pre-existing sense of reality before putting in sufficient effort to discover contradictory evidence. Confirmation bias can clearly be understood within this framework and Fiske and Taylor’s (1984) description of humans as ‘cognitive misers’, who avoid expending time and effort on cognitive tasks and use heuristics or mental short cuts is particularly salient.One field in which confirmation bias can lead to devastating consequences is medicine, where misdiagnosis could lead to incorrect treatment, further health complications or even death. It has been argued that doctors often selectively attend to information which confirms a preliminary diagnosis, failing to attend to contradictory signs and symptoms which are suggestive of a different diagnosis or the alternative possibility, that the patient is in fact disease-free. For example, a patient may have been diagnosed with migraine following presentation with headaches, at which point the doctor may not pick up on signs of forgetfulness or co-ordination problems, which could denote a more serious issue such as a brain tumour. Confirmation bias may also mean that the doctor asks leading questions which mean that the patient is more likely to provide information that fits with the doctor’s expectations, e.g. do have any visual disturbance prior to the headache coming on?Mendel et al. (2011) aimed to show how confirmation bias can affect the validity of psychiatric diagnoses. Specifically they were interested in whether confirmation bias limited the search for new information once a preliminary diagnosis had been made, how this affected the final diagnosis and whether this negatively affected treatment recommendations. Mendel decided to compare psychiatrists and medical students, therefore the participant’s level of experience was the independent variable in this quasi-experimental study and it was hypothesised that the less experienced student group would be more prone to confirmation bias. 75 psychiatrists (44 men, 31 women, average age 35, with average of 6 years professional experience) were selected from two state and one university hospital and compared with 75 fourth-year medical students (31 men, 43 women, average age 25) who were completing a one-week internship in a psychiatric hospital. All participants were shown a vignette about a 65-year-old male patient with depressive symptoms who had been admitted to a psychiatric hospital due to an overdose. Participants had to make a preliminary diagnosis of either Alzheimer’s or severe depressive episode. 96% of the sample initially diagnosed depression. Next, the participants were given the option of receiving access to further information about the patient. They were given 12 summary statements, six relating to Alzheimer’s and six to depression and asked to tick which ones they would like to read in full. Summaries included sentences such as ‘A hint of the presence of Alzheimer’s disease could be that the patient shows memory problems’, if the participants ticked this option they would then be given more detailed notes of around 150–175 words. The detailed chunks of information were presented one at a time and participants were allowed as many pieces of further information as they wished before making their final diagnosis, at which point they were also asked to suggest a course of treatment. All the detailed information was strongly suggestive of Alzheimer’s and not depression, unlike the summary statement which were deliberately more balanced. The dependent variable was how many pieces of further information were requested and whether the participants’ information search was classified as confirmatory (they asked for at least one more piece of information, linked to their initial diagnosis), balanced (they asked for the same number of pieces of information linked to the two diagnoses), or disconfirmatory (they asked for at least one more piece of information linked to the alternative diagnosis).The number of pieces of additional information requested did not differ significantly between the psychiatrists and the students (the mean was 8/12 for both groups). However, psychiatrists were significantly more likely to ask for disconfirmatory items of information, than confirmatory items (p< 0.001) whereas the students’ information search was more balanced, although this was not significant, p=0.23. Overall, a total of 13% of psychiatrists and 25% of students showed confirmation bias when searching for new information and participants conducting a confirmatory information search were significantly less likely to make the correct diagnosis compared to participants searching in a disconfirmatory or balanced way. For example, 70% of psychiatrists and 63% of student who used the confirmatory style ended up making a wrongful diagnosis. The number of information items searched significantly predicted diagnostic accuracy, with participants selecting six or less items showing poorer diagnostic accuracy compared to participants selecting more than six items. Unsurprisingly, participants who chose the wrong diagnosis also prescribed different treatment options compared with participants who chose the correct diagnosis.This study clearly shows how confirmation bias can affect decision-making in the field of psychiatry and Mendel goes onto explain that confirmation bias is often more common on inexperienced thinkers compared with experts. This is possibly explained by cognitive dissonance theory, i.e. if people think that a certain outcome is the case e.g. the patient has depression, then being confronted with contradictory evidence (the patient is showing signs and symptoms of Alzeimer’s) creates an cognitive dissonance which is reduced without the apparent challenges of changing one’s original position, by searching for additional supportive evidence whilst ignoring information to the contrary. ................
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