Criminal Practical Investigation

Question 1

Aim

Answer 1

To see if leading questions affect the answers given by participants who have viewed a video of a car accident.

Question 2

Variables

Answer 2

IV: whether leading questions are used (‘the’) or not (‘any’)

DV: whether participants recall seeing broken glass or not

Question 3

Alternative hypothesis

Answer 3

There will be a significant increase in the number of participants who answer ‘yes’ to having seen broken glass in the leading question condition compared to the non leading question condition.

Question 4

Null hypothesis

Answer 4

There will be no significant increase in the number of participants who answer ‘yes’ to having seen broken glass in the leading question condition compared to the non leading question condition; any increase will be due to chance.

Question 5

Participants

Answer 5

> 23 Ps
females and males
aged 10-69

Question 6

Sampling method

Answer 6

Opportunity

Question 7

Participant design (& justification)

Answer 7

Independent measures

Ps only take part in one condition to avoid realising the aim when given the second questionnaire

Question 8

Apparatus

Answer 8

> Loftus & Palmer’s car crash film clip

> 2 types of questionnaires: ‘the’ and ‘any’

Question 9

Procedure

Answer 9

1: Ps asked to take part
2: Ps watch video clip once
3: Ps allowed as long as they want to complete one of the two questionnaires
4: Ps given debrief

Question 10

Ethics

Answer 10

> Ps gave consent

> Ps given debrief & reminded of right to withdraw

> Informed consent not gained

Question 11

Results

Answer 11

YES - ‘the’: 7 Ps
YES - ‘any’: 5 Ps
NO - ‘the’: 5 Ps
NO - ‘any’: 6 Ps

Question 12

Statistical analysis

Answer 12

x2 = (O-E)2 / E
E = row total x column total / overall total
x2 = 0.3823

Question 13

Conclusion

Answer 13

> no significant difference

> accept null hypothesis

Question 14

EVALUATION: Generalisability

Answer 14

+ age range of 59 yrs - representative of people of many ages

• small sample size
• Ps all from same area of UK

Question 15

EVALUATION: Reliability

Answer 15

+ laboratory conditions & standardised procedure - controlled extraneous variables

Question 16

EVALUATION: Application

Answer 16

+ advice to police/court - eyewitness testimony is reliable

Question 17

EVALUATION: Validity

Answer 17

+ quantitative data means no researcher bias & objective research

• low ecological validity due to lab experiment - could have led to demand characteristics
• low task validity - unlike real life situation (stressful, emotional, in shock, unprepared)
• independent measures P design - P variables (age, gender)

Question 18

EVALUATION: Ethics

Answer 18

+ consent
+ right to withdraw
+ brief & debrief
+ confidential (no record of name)

• no informed consent
• video could have been stressful to some Ps

Question 19

Improvements for the future

Answer 19

> larger sample - increased validity

> gain presumptive consent - increased ethics