Wednesday, December 16, 2009

Twelve Angry Men, and the unreliability of eyewitness testimony

The assignment: Watch the movie "Twelve Angry Men" and talk about the unreliability of eyewitness testimony, citing specific examples

Eliyahu N Kassorla
Twelve Angry Men

The right to a jury trial is guaranteed in the sixth amendment. The framers believed that the right was so valuable that there needed to be a guarantee against its infringement. Eyewitness testimony, however, is much older than that. In our modern time, far too much reliability is entrusted with eyewitness accounts and their accuracy, and we are far too trusting of a jury of our peers.
Eyewitness testimony is very powerful. In many cases eyewitness testimony is often the deciding factor. Juries and judges alike are far too quick to accept an eyewitness at face value. Eyewitnesses may have ulterior motives such as immunity from prosecution if they are involved, for example. They may also have either indirectly witnessed an event and later “filled-in” the details using cognitive heuristics or utilized the constructive nature of memory to add details. Mental heuristics may have filled in large blocks of details, which the brain uses for filling in information.

In the famous Elizabeth Loftus’s study where the “Lost In The Mall” technique was developed, Loftus specifically showed us that memory is not as reliable as we would like it to be. Twenty five percent of subjects recalled an event that they were told had happened to them as children, stories that Loftus attributed to being recounted by an actual relative, as if it had actually happened (Loftus 1995). In the movie, much dialogue was utilized for discussing the fact that there were two witnesses who allegedly saw the crime: one while the crime was being committed, the lady seeing the crime through the L-Train; and one shortly after, the old man seeing the boy flee the apartment. However, the main character showed that the witnesses could not have possibly seen the event.
There also seems to be a special auditory pathway that encodes directly to memory, as people treat information received audibly as already having happened. (Loftus 1995, &c.). The testimony may have been prejudiced by news reports or police questioning.
Another problem is in cases where eyewitness testimony is the only form of evidence available. In the movie, all other evidence was circumstantial, such as the lost knife, of which a reproduction or the original was found at a local pawn shop. The fact that people may have seen things is not conclusive proof. In cases where there is no hard, physical evidence, there cannot be the sole reliance on the memory of witnesses. There are many possible sources of error in eyewitness testimony. Flashbulb memories, as described by E. Bruce Goldstein in his Cognitive Psychology textbook, describes a type of memory that has the same properties and detail recollection accuracy as normal memories, i.e. declining over time, but with the unique property of a disproportionately high confidence of the detail. It usually describes major events, such as the Challenger explosion, the assassination of President Kennedy, the Columbia incident, or, more recently, 9/11. In the movie, the witnesses recalled their memory as being “clear as day,” as one juror noted about the old woman’s testimony. Further, the accounts were very florid and detailed and the old woman remembered every detail, including peripheral details. These “reek” of a flashbulb memory. There is a known negative correlation between accuracy of memory and amount of peripheral details recalled. (Nessier 1982, Weaver 1993). The Yerkes-Dodson Law (Yerkes & Dodson 1908) relates the performance ability of both encoding and recall of memories against physiological or psychological arousal (Figure 1). In the movie, a central premise was the inability of the boy to remember key events; such as the name of the movie he saw (which he said was “uninteresting”) during the questioning by the police that occurred upon his return home and finding his father murdered; which is explained in light of the Yerkes-Dodson Law. Further, the encoding quality of the eyewitnesses must be called into question because they had allegedly seen the crime take place, and witnessing a crime is physiologically and psychologically arousing. Meiser-Stedman , 2002, writes that the “[o]nset of posttraumatic sympomatology may be strongly related to the quality of the memory laid down during the traumatic event.” The inaccuracies in memory during testimony may also be impacted by stress hormones, and high levels of psychological arousal, which are known to interfere in encoding details from STM to LTM. (Meiser-Stedman 2002).
In jury dynamics, and indeed in all groups, minority influence plays a very important role. At the beginning of the movie, the lone holdout from guilty verdict had no significant differences from other jury members. This underlies the similarity principle. Further, he caused a shift in the way of thinking of other members of the group, fragmenting the group and gradually convincing them of reasonable doubt. He turned them one by one by the use of logic and rational thought, forcing them to defend an untenable position. This allowed others to be free to express their doubts because there was already an objector in the group. In order to try and maintain the group using threats of ostracization, the loudmouth objector to dissent from a quick guilty verdict tried to expose those who voted against the group in the secret ballot, attempting to demean and denigrate the dissenters and force them into line with his beliefs. Further, placing the minority on defensive, the logic and ration of the arguments began to sway the swing voters, forcing then the more emotional arguments of the guilty (then-majority) verdict to have to be on the defensive. This utilized the central and peripheral route of persuasion established in the elaboration likelihood model. The logic and rationality of arguments takes the central route and the emotion uses the peripheral route. The central route path always forms a more stable and hardy cognition (Petty & Cacioppo 1986). The jury may be making use of the principle of cognitive conservation, where the likelihood of re-thinking, re-sorting, and re-categorizing something is directly related to the need to. As I said before, mental heuristics is the shortcut. One such heuristic is that "caught=cheating", and the witnesses utilize the auditory pathway creating a confirmation bias problem – where new information is categorized in such a way to confirm the cognition. Humans have a very good detector of cheating, as shown by various experiments on the Wason four-card selection task (as explained in Goldstein 2004). Another possible heuristic is that if the trial had ended without the case being dismissed, the defendant must be guilty. This underlies several logical errors: affirming the consequent and denying the antecedent, which both lead to invalid conclusions without speciousness. In the movie, several of the emotional arguments were based on these invalid syllogisms.
This leads directly to defendant characteristics other than race, such as socioeconomic status (SES), which is influenced by a key logical error: the ad hominem attack. One character described the poor as being criminals because they live in slums which breeds “animals”, therefore the defendant is a criminal. Further, the jurors were hardly peers of the defendant in the movie; all of them held prestigious jobs and had a family or outside life. The jurors who were trying to hurry up the deliberations kept reminding everyone, and nagging, that they had plans that day and wanted to make it quick. Of course, because of the confirmation bias and law of cognitive conservation, all but one supported the guilty verdict, overlooking the inaccuracies of the story, errors in logic, and a case based solely on circumstance and inference.


Cosmides, L. (1989). The logic of social exchange: Has natural selection shaped how humans reason? Studies with the Wason selection task. Cognition, 31, 187-276.

Goldstein, E. Bruce (2004). Cognitive Psychology. Wadsworth Publishing

Loftus, E., & Pickrell, J. (1995). The formation of false memories. Psychiatric Annals, 25(12), 720-725.

Meiser-Stedman, R. (2002). Towards a cognitive-behavioral model of ptsd in children and adolescents. Clinical Child and Family Psychology Review, 5(4), 217-230

Neisser, U. (1982). Memory observed: remembering in natural contexts. San Francisco: Freeman.

Petty, R.E., & Cacioppo, J. T. (1986). Communication and persuasion: Central and peripheral routes to attitude change. New York: Springer/Verlag.

Weaver, C.A., III. (1993). Do you need a "flash" to form a flashbulb memory? Journal of Experimental Psychology: General, 122, 39 -46

Yerkes, R.M. & Dodson, J.D. (1908), The relation of strength of stimulus to rapidity of habit-formation. Journal of Comparative Neurology and Psychology, 18, 459-482
Figure 1

(Yerkes, R.M. & Dodson, J.D. (1908), The relation of strength of stimulus to rapidity of habit-
formation. Journal of Comparative Neurology and Psychology, 18, 459-482)

1 comment:

  1. Nice job, I am reviewing "12 Angry Men" for my MBA program to study influence techniques. Was interesting to see it approached from another perspective!