Forensic psychology
Forensic psychology

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Forensic psychology

2.2.2 Re-evaluating the statements

Figure 8

You know now that a question can suggest a response, that the co-witnessing effect tends to make evidence from two witnesses very similar, and that people tend to judge height and weight badly as the judgements are made relative to their own build.

To help you evaluate the statements taken by DI Bullet, in the next activity you look at potential ways that evidence can become biased. For each question, you will be provided with a specific statement that was obtained by DI Bullet in the audio you heard. Your job is to decide whether the statement is likely to have been biased by one of these three factors:

  • Biased as it was suggested by the question asked – for example, did DI Bullet ask a question in a way that suggested what the answer should be, or suggest information to the witness that they had not mentioned before?
  • Biased because of the co-witnessing effect – did the witness remember the information themselves, or had they heard another witness say something similar?
  • Biased as witnesses tend to over and underestimate height, weight, distance and time.

Alternatively, the evidence might not have been influenced by any of the above factors, in which case you should select:

  • Potentially unbiased.

The statements that appear in the quiz are all taken from the recording of DI Bullet you heard in DI Bullet: initial statements. Do feel free to re-listen to this audio as many times as you like.

Activity 2.2 Evaluating bias (DI Bullet)

Allow about 10 minutes

Q1. ‘Lila states that the suspects drove up and jumped out of a car.’ This piece of evidence is:

a. 

Biased as it was suggested by the question asked.


b. 

Biased because of the co-witnessing effect.


c. 

Biased as witnesses tend to over and underestimate height, weight, distance and time.


d. 

Potentially unbiased.


The correct answer is a.

a. 

Well done! DI Bullet asks ‘I understand you mentioned that the suspects drove up and jumped out of a car, could either of you describe it?’, so his question suggested that the suspects drove up and jumped out of a car.

Do re-listen to the audio of DI Bullet taking the statements, and consider how this piece of evidence was obtained.


Q2. ‘Seth states that the car was large and silver.’ This piece of evidence is:

a. 

Biased as it was suggested by the question asked.


b. 

Biased because of the co-witnessing effect.


c. 

Biased as witnesses tend to over and underestimate height, weight, distance and time.


d. 

Potentially unbiased.


The correct answer is b.

b. 

Well done! This piece of evidence was provided only after the witness had heard it stated by another witness.

Do re-listen to the audio of DI Bullet taking the statements, and consider how this piece of evidence was obtained.


Q3. ‘Lila states that the kidnapper was the driver.’ This piece of evidence is:

a. 

Biased as it was suggested by the question asked.


b. 

Biased because of the co-witnessing effect.


c. 

Biased as witnesses tend to over and underestimate height, weight, distance and time.


d. 

Potentially unbiased.


The correct answer is b.

b. 

This is correct. This piece of evidence was provided only after the witness had heard it stated by another witness.

Do re-listen to the audio of DI Bullet taking the statements, and consider how this piece of evidence was obtained.


Q4. ‘Lila states that the two masked perpetrators aimed guns at the guards, while the unmasked perpetrator cut free a case chained to one of the guards.’ This piece of evidence is:

a. 

Biased as it was suggested by the question asked.


b. 

Biased because of the co-witnessing effect.


c. 

Biased as witnesses tend to over and underestimate height, weight, distance and time.


d. 

Potentially unbiased.


The correct answer is d.

d. 

This is correct. This evidence does not involve any estimation about height etc., and the witness provided the statement without the information first being suggested in a question or having heard it first stated by another witness.

Do re-listen to the audio of DI Bullet taking the statements, and consider how this piece of evidence was obtained.


Q5. ‘Lila states that the driver was about 6 foot 4.’ This piece of evidence is:

a. 

Biased as it was suggested by the question asked.


b. 

Biased because of the co-witnessing effect.


c. 

Biased as witnesses tend to over and underestimate height, weight, distance and time.


d. 

Potentially unbiased.


The correct answer is c.

c. 

Well done! The witness is estimating the height of a suspect, and is likely to be biased by their own height.

Do re-listen to the audio of DI Bullet taking the statements, and consider how this piece of evidence was obtained.


Q6. ‘Seth states that the perpetrators looked stocky and like bouncers.’ This piece of evidence is:

a. 

Biased as it was suggested by the question asked.


b. 

Biased because of the co-witnessing effect.


c. 

Biased as witnesses tend to over and underestimate height, weight, distance and time.


d. 

Potentially unbiased.


The correct answer is b.

b. 

This is correct. This piece of evidence was provided only after the witness had heard it stated by another witness.

Do re-listen to the audio of DI Bullet taking the statements, and consider how this piece of evidence was obtained.


FPSY_1

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