Eyewitness identification

Eyewitnesses are often considered notoriously unreliable because there are many factors that can influence eyewitness testimony, but is this true? When reporting on a person from memory, certain details may be forgotten and others may be confused (Wright, Memon, Skagerberg & Gabbert, 2009). Therefore, research has focused on various factors that can influence the reliability of eyewitness identifications.

Estimator variables

So-called Estimator Variables are beyond the control of the criminal justice system (Semmler, Dunn, Mickes & Wixted, 2018). Some of these variables are self-explanatory as they influence how well eyewitnesses could view an offender. The distance between the witness and the perpetrator (Lindsay et al., 2008; Nyman et al., 2019), the length of time the witness was able to see the attacker (Carlson et al., 2016), the use of disguises (Papailiou, Yokum & Robertson, 2015), poor lighting (Nymnan et al., 2019a), and the presence of stress all negatively impact the witness's ability to see and remember all definable characteristics of the attacker, reducing the accuracy of identification.

Then there are specific variables that require explanation. There is a phenomenon known as the foreigner effect (own-race bias) According to this variable, eyewitnesses are more accurate in identifying perpetrators belonging to their own ethnic group than to another (Flaskerud, 2020). Secondly, there is the weapon focus effectweapon focus effect(Fawcett, Peace, & Greve, 2016). This is a phenomenon where witnesses are so preoccupied with the presence of a weapon that they forget to look at the perpetrator.

The time interval between the offence and the witness report is also important (length of retention interval), as memory deteriorates over time. This is also confirmed by various studies that showed that the accuracy of eyewitness identification decreases with increasing length of the retention interval (e.g. Palmer et al. 2013; Read et al., 1998; Sauer et al., 2010). Eyewitnesses should therefore be interviewed as soon as possible after a crime.

And what about witness confidence? Is it also a good indicator of the accuracy of eyewitness identification? This claim is difficult to substantiate, as there has not been much consensus on this fact. Research suggests, for example, that most witnesses are overconfident, while they are accurate only 60% of the time (Sauer, Brewer, Zweck & Weber, 2010). For confidence ratings to predict accuracy, it is important to consider the circumstances in which these ratings are made (Wixted, Read & Lindsay, 2016). In a controlled environment where the assessment truly reflects the witness's confidence in the testimony, such as in laboratories, they are indeed accurate. In real life, however, the witness's confidence could be influenced by external factors that distort the ratings. For example, if they are assured by another witness that they saw the same perpetrator.

System variables

The so-called system or control variables are in the control of the legal system, mostly the police. In police line-ups, a witness is presented with a suspect along with other people who are certain to be innocent and similar to the suspect. This can take the form of photos, videos or personal confrontations and can happen simultaneously or consecutively. Again, many studies have tried to make a case for one of the two approaches, but the results are inconclusive. The recent study by Seale-Carlisle, Wetmore, Flowe and Mickes (2019) found that, in practice, the use of simultaneous line-ups led to better results, both in identifying the perpetrator and in not identifying an innocent person, but these results need further investigation.

Apart from that, there are several problems in a police line-up. Sometimes the suspect(s) stand out from the others because they do not resemble each other, as was the case with the Leonard Callace line-up. He appeared with a full beard among five other people who only had moustaches (Colloff, Wade & Strange, 2016). Alternatively, a witness may feel pressured to choose a person even though he/she does not recognise or feel confident in his/her decision. Thus, a witness may indicate which person is most similar to the perpetrator, rather than identifying the perpetrator from memory, in order to please the police. This is particularly detrimental when the police are giving supportive feedback.

Numerous studies have examined the influence of police feedback in line-ups and found that witnesses can be easily influenced (Greenspan & Loftus, 2020). When feedback is given by the police, the confidence of the witness changes significantly and no longer reflects the true confidence of the witness. Of course, as one can imagine, this leads to witnesses who are very confident but provide false identifications, or to insecure witnesses who are perfectly capable of identifying their attacker. Therefore, in order to obtain reliable witnesses, feedback from the police should be limited.

Eyewitness accounts are an important part of crime detection work, but influencing factors in reliability should be examined.


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