Eyewitness evidence is
arguably one of the most frequent and important types of evidence encountered
in a criminal case. Eyewitness testimony has demonstrated to have an enormous
impact in the criminal field as it contributes immensely to the conviction of
an individual. However, eyewitness error is one of the leading causes of
wrongful convictions. For example, the United States has seen more than 250 DNA
exonerated cases (where DNA has proved the innocence of a convicted prisoner),
and alarmingly, eyewitness error occurred in more than 75% of these cases, thus
making it the primary contributing factor to wrongful convictions (Wise et al.,
2009; Innocence Project, n.d.).
Our
memories are malleable, such that they can be altered or influenced by
post-event information like behavioural cues. Behavioural cues can be verbal (wording
of a question) or nonverbal (such as gestures). A great deal of research has
shown the tremendous impact verbal influence has on eyewitness memory. To
illustrate this further, let us briefly turn to a study by Elizabeth Loftus and
John Palmer (1974). In this study, participants were required to watch a short
video of a car accident and answer questions following the clip. One of the
tasks was to identify how fast the cars were going. However, when the researchers
manipulated the verb (e.g. “how fast were the cars going when they smashed/bumped/hit/contacted?”),
participants who were asked how fast the cars were going when they smashed estimated the cars to be
traveling approximately 40.8 mph. Interestingly, when participants were asked
how fast the cars were going when they contacted,
the estimation of speed dropped to 31.8 mph (Loftus & Palmer, 1974). This
research is critical as it demonstrates how simple manipulation of the verb in
a sentence can impact an individual’s memory and response, supporting the
flexibility of our memories and how they can be influenced by verbal cues.
Nonverbal
Influences: What the research tells us.
Without
question, most of the scientific research regarding eyewitness memory focuses
on verbal influences. Therefore, it is imperative that we turn our attention to
nonverbal influences (gestures) in order to determine if such behavioural cues
have a similar effect on eyewitness memory. In fact, when accompanying the
question “did the suspect have facial hair?” with a beard gesture, witnesses incorporated
the information presented through the gestures into their original memory of
the event, such that they reported seeing a beard (Gurney, 2015). Through his
research, Daniel Gurney (2015) successfully demonstrates that nonverbal influences
are comparable to verbal influences, such that misinformation (false
information) can be conveyed through gestures and speech. In his study, Gurney
(2015) had 92 participants watch a video of a staged crime. The clip showed a
girl waiting at a bus stop when a man entered and stole a phone from the bag on
the ground beside her. A few bystanders were present in order to have the scene
appear as real as possible. Next, participants were asked critical questions
about the video regarding the victim’s appearance, the stolen item, where the
suspect put the item, etcetera, while being provided with verbal or nonverbal
suggestions.
These suggestions included factual information
(information congruent with the crime scene) or misleading information (information
that was false). The verbal questioning conditions presented the critical
information through speech. For example: “the item stolen was a phone” (factual), or “the item stolen
was an iPod” (misleading). The
nonverbal questioning conditions presented the critical information through
gestures, while the speech remained unbiased. For example: “an item was stolen”
+ phone gesture (factual), or “an
item was stolen” + iPod gesture
(misleading). A control condition was used, which involved the interviewer
asking unbiased questions without any gestures, for example, “an item was
stolen”. Participants were required to respond with a “correct”, an
“incorrect”, or an “I don’t know” response.
Factual Information vs. Misleading
Information:
The
results indicate that individual responses were affected by the type of
questioning. Therefore, when presented with factual information, participants
were more likely to give a correct response. Nonetheless, when presented with
misleading information, participants were more likely to give an incorrect
response. This is crucial to note because, with regards to eyewitness
testimony, officers do not usually know the correct facts (hence statements
gathered from witnesses). Therefore, if officers fail to ask open ended questions,
they could potentially influence the memory of the eyewitness. For example, if
an individual witnessed the crime shown in the experiment and could not
remember what was stolen out of the bag, but the officer asked if it was an
iPod (instead of asking openly, “what was stolen?”), it is probable that the
eyewitness could have been influenced, leading them to recall that the stolen
item was an iPod, thus providing inaccurate conclusions. Interestingly, the
verbal and nonverbal misleading groups differed significantly from the control
group. What this means, is that unbiased questioning in the control group
elicited more correct responses,
whereas misleading questions or gestures led to more incorrect responses. So in order to increase the likelihood of
obtaining correct or accurate responses, it is best to ask unbiased questions,
allowing the eyewitness to freely recall the event from memory without any
behavioural influences.
So, is there a difference between verbal
and nonverbal influences?
No. Verbal
and nonverbal influences do not differ significantly from each other. However, the
absence of variation among the two should not to be overlooked. In fact, what
this means is that nonverbal cues (gestures) are just as likely to influence memory
as verbal cues. This is imperative to understand because whereas speech is
easier to control and standardize, gestures are harder to inhibit. We have
already seen a well-established verbal misinformation effect, such that when presented
with misleading information, people are more likely to give an
incorrect/inaccurate response. So, if gestures are just as likely to influence
responses, this increases the impact of behavioural influence on eyewitness
memory. Further, it has been suggested that people integrate information from
gestures into speech; eyewitnesses may use information from gestures to
reconstruct their memory. For example, when presented with the statement “my
brother went to the gym” with a “shooting a basketball” gesture, listeners
actually extracted the “basketball” information from the gesture, but also
remembered it as part of the speech (Gurney, 2015). Gestures are an important
part of human communication and may be automatic or implicit, occurring outside
of our awareness, thus harder to control.Therefore, suggesting the ability of gestures to
influence one’s memory, making them critical candidates for influence in
eyewitness memory and error, potentially leading to wrongful convictions.
Going Forward:
This information
can prove to be useful for law enforcement, should they be provided with this
knowledge. Having said that, education and training programs can be created to
raise awareness of behavioural influence. Further, understanding how easily
memory can be altered by not only verbal cues, but nonverbal cues as well, is
crucial for law enforcement, especially when eyewitness testimonies have a
major effect on convicting an individual. Such programs can aid officers in
asking open ended questions, along with helping them develop strategies in
attempt to control the use of gestures. However, as mentioned previously,
gestures sometimes occur without awareness, proving to be difficult to
eliminate or inhibit. As such, it might be more beneficial to create a standardized
method to ensure the reduction or elimination of
behavioural influences, thereby reducing eyewitness error, ultimately reducing wrongful convictions.
-
Brittany Haynes
References:
Gurney, D.J., (2015). What’s left unsaid: How
nonverbal influence compares with verbal influence. Psychiatry, Psychology and Law, 22 (3), 465-473. doi: http://dx.doi.org/10,1080/13218719.2014.985624
Loftus, E.F., & Palmer, J.C., (1974).
Reconstruction of automobile destruction: An example of interaction between
language and memory. Journal of Verbal
Learning and Verbal Behavior, 13
(5), 585-589. Retrieved from PsycINFO
Wise, R.A., Pawlenko, N.B., Safer, M.A., & Meyer,
D., (2009). What US prosecutors and defence attorneys know and believe about
eyewitness testimony. Applied Cognitive
Psychology, 23, 1266-1281. doi:10.1002/acp.1530
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