When discussing finding and collecting psychological evidence at a crime scene, most people think about biological and physical evidence found on the crime scene or in the suspect's belongings, e.g. fingerprints, hair, a tooth, murder weapon, blood, CCTV footage, etc. However, many often forget about psychological evidence in a crime, which can provide valuable information.
- We are going to explore psychological evidence in the courtroom. First, we will provide a psychological evidence definition.
- We will also discuss various examples of psychological evidence.
- Then, we will delve into the different types of evidence in psychology, including psychological evidence at a crime scene.
- We will explore how psychological evidence is used in court.
- We will also cover the cognitive interview, the standard interview, and the application of police interview strategies.
Fig. 1 - Forensic psychology explores psychological evidence when investigating crime.
Psychological Evidence Definition and Examples
Psychological evidence in crime often relies on memory. The encoding specificity principle suggests cues enhance the retrieval of memory traces, especially if those cues are associated with the retrieved information. When interviewing suspects and victims, cues are often great for improving memory retrieval, but cues can influence a person's memory if the police interview is not conducted carefully.
The standard interview is a standard technique the police use, but the cognitive interview was developed as an alternative.
Psychological evidence includes the suspect's mental state, their written and spoken accounts of what they believed happened, their testimonies, and any medical diagnoses or prescriptions they may have been given by credible professionals. Specifically, we can define psychological evidence as follows.
Psychological evidence is anything regarding the suspect's mental state that proves they committed the crime.
We briefly mentioned examples of psychological evidence above; here is an overview of examples of psychological evidence:
- Testimonies
- Reports
- Written analysis
- Diagnostics on psychological or psychiatric matters
- Other fact witnesses
- Medical prescription of the suspect for any psychological condition
- Expert witnesses (e.g. a psychologist, psychiatrist, counsellor, or therapist)
Types of Evidence in Psychology
Evidence can be biological and psychological. Biological evidence involves analysing fingerprints, using DNA samples such as blood work and obtaining hair and skin cells.
The two main ways that psychological evidence can be obtained are through interrogations and interviews. There are distinct differences between interrogations and interviews.
Interrogations | Interviews |
Accusatory | Non-accusatory |
Used to obtain a confession that is admissible in court | Involve a dialogue consisting of questions and answers |
Involve a monologue by the detective to encourage the suspect only to talk when they're ready to speak the truth | A way to collect relevant information about the crime |
| Can evaluate the suspect's truthfulness and the need for interrogation |
Psychological Evidence at a Crime Scene
By using interrogations and interviews, we can attain helpful evidence of the crime, for instance, what exactly happened at the crime scene, who was present, and what the suspect's role was, amongst other things.
Psychological Evidence in Court
Psychological evidence that can be used in court includes the testimony of a witness to the crime. Witnesses usually take the stand, but an audio/videotape can be submitted in special circumstances, or they can give testimony behind a screen, e.g., in the case of child witnesses.
However, before the case is taken to trial, the police question witnesses to understand what happened at the crime scene.
Examples of Psychological Evidence
As you will have covered in the Memory topic, Loftus and Palmer (1974) found eyewitness testimony isn't always accurate and can be altered by the interview itself, particularly by misleading questions. These questions insinuate an answer, leading to distorting the witnesses' memory.
The Standard Interview
The standard interview is an interview that doesn't require training (Brewer, 2000). Interviewers can ask any questions they want if they feel it is relevant and will get them useful information. Gudjonsson (1992) highlighted the four stages involved in a standard interview:
Orientation
Listening
Questions/answers
Advice
The Cognitive Interview
The cognitive interview was developed to address issues with the standard interview, namely leading questions, interruption issues, and event sequencing. Geiselman et al. (1992) developed the cognitive interview (CI) to overcome the disadvantages of the standard interview. It takes many things into account, such as cue-dependent forgetting.
There are four steps to the CI.
Cognitive Interview Steps |
Step 1: Context reinstatement | The witness mentally put themselves in their position during the crime, imagining what it was like at the time and their internal state. |
Step 2: Narrative re-ordering | The witness tries to recall the event in a different order from how it occurred (e.g., backwards), so schemas don't alter what happened and form false memories. |
Step 3: Report everything | The witness reports everything they can remember in as much detail as possible. The smallest details can trigger important memories. |
Step 4: Recalling from different perspectives | The interviewer asks the witness to describe how the event would have looked from someone else's perspective, e.g. a different witness, the victim, or the suspect. |
Fisher et al. (1990) trained detectives from the Miami Police Department on using the CI to interview their potential suspects. Interviews were recorded with eyewitnesses and victims, and a further eyewitness confirmed or denied the statements procured in the interview.
They found that the CI had a 46% increase in recall and a 90% increase in accuracy, lending credence to the efficacy of the CI. Later, Fisher and Gieselman (1992) revised their CI to see if they could further improve it and found 45% improvements compared to the standard interview.
Review of the Cognitive Interview – Memon and Higham (1999)
Memon and Highman (1999) sought to critique the cognitive interview in their article, discussing four themes:
Effectiveness of the components of the cognitive interview
Isolating the effective components of the CI
The enhanced CI
Comparison interviews
Fig. 2 - Different interview styles can be used to investigate crime.
Components of the Cognitive Interview
Memon and Higham (1999) highlight the frequently used components of the CI. Mental reconstruction of the external and internal contexts during the crime involves mental and physical states, including the presentation of the scene, and emotions felt during the time.
All five senses (sight, sounds, smell, etc.) are discussed for effectively retrieving memories and implementing cues.
Witnesses reporting everything they can remember without dismissing any information will yield additional recall of memories and aid in combining multiple witness statements to create an overall picture. A recollection from different points of view, where witnesses effectively view the crime from a different person's perspective, using multiple retrievals cues to increase the detail of information.
However, different perspectives can cause issues with the fabrication of information and cause some confusion (Memon and Koehnken, 1992). Milne (1997) found that perspective-shifting is not particularly effective in increasing information recollection compared to other CI techniques.
A recollection from different starting points is used to aid retrieval and accuracy of memories (as well we determine the truthfulness of those being interviewed). Gieselman and Callot (1990) found recalling forwards once and then backwards once was more effective.
Isolating the Effective Components of the Cognitive Interview
The different components of the CI were tested separately to find the most effective one. Memon et al. (1996a) interviewed 5–8-year-old child participants acting as witnesses of a staged event using one of the CI components: context reinstatement (CR), change perspective (CP), or change order (CO).
The 4th was a control group and was simply told to 'try harder'. They found that across all four groups, there were no differences in recall performance.
They also replicate these results in a second experiment with 5–9-year-olds (Memon et al. 1996a Experiment 2). These findings suggest the CI is effective because witnesses, when prompted, have additional retrieval attempts, which elicit new details.
Milne (1997) tested adults with the full CI (all four components) and its separate components (CR, CP, CO, and report everything, RE). She found that out of the four components, there were no differences in correct or incorrect details compared to the control condition. Overall, the full CI condition produced more recall than the separate components, except for the context reinstatement condition.
Context Reinstatement appears to be the most effective component of CI.
Enhanced Cognitive Interview (ECI)
The enhanced cognitive interview (ECI) combines the four CI components with additional strategies to improve the CI process further, as mentioned briefly above.
Transfer of control is used to build rapport, reduce interruptions, and encourage elaborate responses through open questions and timing of questions to aid the retrieval of memories. This naturally facilitates each component of the CI; by building rapport, the witness is relaxed and open to further CI techniques.
They also mentioned how the components of the ECI, improved communication and improved retrieval of information, work in interaction with each other to get maximum effectiveness (McCauley and Fisher, 1995).
Several studies providing evidence for the memory enhancement technique 'imagery' efficacy are also listed and discussed in this review section. Forming a mental image probed by questions elicits more detail and better retrieval. Imagery effects on information retrieval include reality monitoring and task demands; however, repeated requests to imagine pictures caused participants to create false reports (Johnson et al., 1979).
When asking witnesses to create images, caution is advised.
Comparison Interviews
The CI has been compared with the Standard Interview, the Guided Memory Interview, the Structured Interview (SI), and hypnosis. Hypnosis isn't focused on due to a lack of evidence that it is effective for improving recall. Research often compares the CI to the Standard Interview.
However, psychologists argue this isn't an appropriate comparison because they are too different.
- The CI requires proper training, while the Standard Interview doesn't.
- The Standard Interview can't control for individual differences of the interviewer, but since the CI has a standardised procedure, the issue doesn't apply.
The CI was developed as a replacement for the Standard Interview to be used by the authorities, and original research sought to prove that it was better than the Standard Interview. But now, since that has been established, it's no longer appropriate in future research to compare it to the Standard Interview when evaluating its effectiveness but to evaluate its components instead.
Memon and Higham proposed that although the Standard Interview was an appropriate tool for comparison in the early days of research into the CI, it is no longer applicable. They advise against using the Standard Interview to compare and evaluate the efficacy of the CI.
Guided Memory Interview (GMI)
The GMI uses the principles of context reinstatement and encourages the witness to reinstate contexts, so their memory is guided. Malpass and Devine (1981) tested the effectiveness of the GMI and found that it was more effective in eyewitness identification (EWI) accuracy than simply prompting with lineup instructions.
However, while techniques of the GMI resemble the CR and imagery component of the recent CI, research has shown that the CI doesn't lead to increased accuracy in EWI. The GMI study by Malpass and Devine (1981) may be because they used detailed probing, which resulted in enhanced memory, which wasn't present in CI or other GMI studies, so they failed to find enhanced memory effects.
Another point mentioned was that if the event was recent, CR might not enhance memory much, but if there's been a gap, it will be useful in enhancing memory (Smith, 1988).
Therefore, the GMI may be a good comparison for the CI since they share the CR component. However, it may not be a good comparison because it doesn't include other important techniques of the enhanced CI that make it effective, e.g. building a good rapport with witnesses.
Structured Interview (SI)
The SI encourages the interviewer to build a rapport with the witness, give them time to respond and give them a chance to give narrative descriptions. It's expansive, non-interrupting, and confidence-building and uses good questioning techniques: open questions, actively listening, and suitable non-verbal behaviour.
- Koehnken et al. (1994) first compared the SI to the CI.
- Memon et al. (1997b) suggest that both the CI and SI produce effective results with proper training.
The main difference between SI and CI is the cognitive techniques in CI, which suggests SI is good for determining the efficacy of the techniques in SI.
Different Measures of the Performance of Memory and its Effect on Findings
In the majority of the studies, the performance of memory is measured by the number of interview statements that are correct or incorrect. However, one problem with this is that it doesn't account for the memory of unreported information, which should be the aim when evaluating the effectiveness of any interview.
An example of this could be that when the interviewee is asked only to tell the truth, they may leave out information they aren't 100% sure about.
So, further research needs to be conducted to improve the interview's techniques and, therefore, increase the amount of reported information that could be useful.
Interviewer Variables and Training Quality's Effect on Interview Performance
A criticism of the early CI studies is that the quality and amount of time of training given to the interviewers weren't controlled, and they were receiving different amounts. Differences in the interviewer's motivation, attitude and prior experience may play a significant role in what kind of results will be gained from the CI.
Therefore, Memon and Kelling suggested a few things for the training process:
- Interviewers should be given proper training for techniques involved in CI. The recommendation would be a 2-day training programme.
- Another way would be to focus on training the CI detectives who are already good interviewers and giving those who are bad interviewers other roles in police work, assuming that training the good ones will improve them.
Application: Police Interview Strategies
A framework has been suggested for conducting interviews with witnesses.
P.E.A.C.E. Interview Framework
The P.E.A.C.E. interview framework stands for Plan, Engage, Account, Closure, and Evaluate.
| The P.E.A.C.E Interview |
| P | Plan and prepare | Even as much as determining the aim(S) of the interview. Any potential barriers, e.g. language or a vulnerable witness, should be planned to be overcome. |
| E | Engage and explain | The interviewer should explain the purpose and process to the witness and build a rapport to put them at ease. |
| A | Account: classification and challenge | A full account of the event is obtained from the witness without interruption, then there should be techniques used to re-attempt recalling the same or similar, relevant information. |
| C | Closure | End in a good way so the witness won't be opposed to another interview. |
| E | Evaluate | The information gathered should be evaluated to determine if it's enough or if there are any inconsistencies. |
Psychological Evidence - Key takeaways
- Psychological evidence is anything regarding the suspect's mental state that proves they committed the crime.
- The Standard Interview (SI) is a common technique the police use when interviewing witnesses.
- CI is more effective than SI and uses four key components: context reinstatement, narrative re-ordering, reporting everything, and recollection from different perspectives.
- Memon and Higham (1999) reviewed and evaluated many areas of the CI using four key themes: components of the cognitive interview, isolating the effective components of the CI, the enhanced CI, and comparison interviews.
An application of research is police interview strategies such as the PEACE Interview Framework, which includes: planning and preparing, engaging and explaining, accounting, closure, and evaluate.
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