The confirmation bias in the forensic sciences.

James and Nicki always wanted to work in the forensic sciences. Whilst reading towards their undergraduate degrees they would borrow as many books from the library as they could on forensics and watch the popular television programmes about ‘forensic experts.’ One day when looking though an interesting book about case studies in forensics Nicki came across an interesting case study.

In 1988, Barry Laughman confessed during interrogation to the charges of rape and murder of his neighbour. The following day tests revealed that the person who committed the crime had Type A blood whilst Laughman had Type B. Aware that Laughman had confessed to the crimes the state forensic chemists proposed four theories (none of which were scientific) to dismiss the mismatch. Laughman was in due course convicted and sentenced to 16 years in prison. He was eventually released in November 2003 after a re-examination of the DNA evidence.

The case of Barry Laughman gives us a clear example of the influence of confirmation bias in the forensic sciences. The confirmation bias is shown when an individual ignores evidence that goes against what they believe whilst trying to confirm the belief (Dror, 2006). In Barry’s case the Virginian state forensic chemist ignored contradictory evidence and persisted in dismissing the mismatch in DNA evidence.

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The confirmation bias causes problems in all areas of decision-making. In the forensic sciences errors in decision-making, as caused by the confirmation bias can have severe consequences innocent people can spend a lifetime in prison, and the actual criminal can go on to reoffend. In the forensic sciences, the confirmation bias has been reported by the National Academy of Sciences (2009) in firearms, hair and fibre analysis, blood splatter, hand-writing and fingerprints (Kossin et al., 2013; Garrett et al., 2011).

In a recent study investigators found an interesting example of how the confirmation bias can influence the outcome of a forensic analysis (Ulery et al., 2012). The investigators gave forensic fingerprint examiners the same evidence twice, at approximately 10% of the time the examiners reached different conclusions (Ulery et al., 2012). Three of the reasons as to why the examiners reached differing conclusions are (i) examiners often receive direct communication from the police (e.g., letters, phone calls etc), (ii) cross-communication between examiners, and (iii) examiners overstating the strength of evidence.

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There are measures that can be taken to prevent the confirmation bias. The FBI’s Latent Print Unit revised their Standard Operating Procedures (SOP) (Cole et al., 2005). They adopted a programme of masked verification whereby fingerprint comparisons that involve a single print are masked-verified (i.e., in isolation with no further information about the print). The change in SOP prevents the second examiner from inferring the first examiner’s conclusion when two examiners individually examine the evidence (Office of the Inspector General, 2011).

Other measures that can be undertaken to prevent the confirmation bias include training all forensic examiners so that they know about cognitive biases. Just two of the courses help to install knowledge of cognitive biases are the FBI’s week-long Facial Comparison and Identification Training and the Australian government’s 2-day long facial comparison course. The linear examination of evidence by multiple examiners (Heyer et al., 2013), cross-laboratory verification (Kossin et al., 2013) and peer verification (Heyer et al., 2011) can all help in reducing the impact of the confirmation bias in the forensic sciences.

So, like James and Nicki if you are interested in working in the forensic sciences it is important to learn about the influence of cognitive biases on decision-making. Some private forensic companies have begun to provide training for their employees, and some governments have started to provide training. With adequate training one day we may be able avoid false convictions.


The recognition heuristic in advertising

The recognition heuristic in advertising

Anton and Sarah were shopping for their weekly groceries in their local supermarket. They bought their regular fresh fruits, vegetables, meat and dairy. As they started down the cleaning aisle Anton and Sarah were trying to decide which furniture polish to buy. They looked at the choice of polishes that were stocked in the aisle. There was a supermarket own-brand choice, two little known choices and a well-known brand. Anton remembered the well-known brand of furniture polish from a television advertisement with a comical cartoon character. There was little difference between the prices so Anton and Sarah decided to opt for the well-known brand that they remembered from the television advertisement.

Like the furniture polish brand companies spend great fortunes on making their products well-known. Millions is spent on brand communication with the goal of achieving the aided and unaided awareness of products. In 2007 and 2008 two large brands, Proctor and Gamble and Unilever spent $5.2 billion and $7.8 billion respectively. The substantial resources that are committed to promoting brand awareness shows the importance of establishing and retaining the awareness of a brand.

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Because of the importance of brand awareness many companies and academics have sought to understand the decision processes that are involved when a consumer chooses one brand over another. In industry, a major US automobile brand invested substantial resources to study how they might persuade customers to choose their brand over their competitors. They found that although their brand had excellent new vehicles as judged by independent raters two thirds of US consumers did not consider their brand (Hauser et al., 2011). The automobile company lacked a memorable advertising campaign.

In academia, researchers at the Max Planck Institute have suggested a rule-of-thumb (i.e., heuristic) that attempts to explain why consumers choose one brand over another (Gigerenzer & Goldstein, 1999, 2011). In a now famous experiment where participants were given the names of two cities (e.g., Oxford or Lannion), and then asked to judge which of the two cities had the largest population, participants reliably choose the city they knew (i.e. Oxford) over the city that they did not (i.e. Lannion). The researchers recorded this rule-of-thumb as… If one of two objects is recognized and the other is not, then infer that the recognized object had the higher values with respect to the criterion. The researchers called this rule-of-thumb the recognition heuristic. In consumer psychology, the recognition heuristic works equally well when consumers are asked to choose one brand over another (Thoma et al., 2013; Oeusanthornwattana & Shanks, 2010).

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In purchases with higher stakes (compared to simply buying a product in a shop) such as stock market investments the recognition heuristic is also of use. Imagine that you wish to invest a particular amount of money in stocks. If one person recognises a stock name over another they are more likely to choose the known stock over the unknown stock. Having a recognised stock name can increase the number of investors in a certain stock (Erdfelder et al., 2011).

In the case of Anton and Sarah shopping for their furniture polish it is clear why they choose the well-known brand over the unknown polish. The advertising campaign of the branded furniture polish with the comical cartoon character aided in the recognition of this brand thereby resulting in one more sale. If you multiple Anton and Sarah’s purchase by thousands or millions then you can clearly see the huge amounts of money that are involved. Many of us, like Anton and Sarah stick to brands we know simply because we know them, we buy the same cleaning products and food stuffs because of successful brand awareness campaigns that act on the recognition heuristic. Perhaps if we wish to avoid making unconscious choices based on the recognition heuristic we could simply try a different product, afterall the new product is not as we expect we can change back to our regular shopping pattern next time.