Criminal Practical Investigation Flashcards
Aim
To see if leading questions affect the answers given by participants who have viewed a video of a car accident.
Variables
IV: whether leading questions are used (‘the’) or not (‘any’)
DV: whether participants recall seeing broken glass or not
Alternative hypothesis
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.
Null hypothesis
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.
Participants
> 23 Ps
females and males
aged 10-69
Sampling method
Opportunity
Participant design (& justification)
Independent measures
Ps only take part in one condition to avoid realising the aim when given the second questionnaire
Apparatus
> Loftus & Palmer’s car crash film clip
> 2 types of questionnaires: ‘the’ and ‘any’
Procedure
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
Ethics
> Ps gave consent
> Ps given debrief & reminded of right to withdraw
> Informed consent not gained
Results
YES - ‘the’: 7 Ps
YES - ‘any’: 5 Ps
NO - ‘the’: 5 Ps
NO - ‘any’: 6 Ps
Statistical analysis
x2 = (O-E)2 / E E = row total x column total / overall total x2 = 0.3823
Conclusion
> no significant difference
> accept null hypothesis
EVALUATION: Generalisability
+ age range of 59 yrs - representative of people of many ages
- small sample size
- Ps all from same area of UK
EVALUATION: Reliability
+ laboratory conditions & standardised procedure - controlled extraneous variables
EVALUATION: Application
+ advice to police/court - eyewitness testimony is reliable
EVALUATION: Validity
+ 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)
EVALUATION: Ethics
+ consent
+ right to withdraw
+ brief & debrief
+ confidential (no record of name)
- no informed consent
- video could have been stressful to some Ps
Improvements for the future
> larger sample - increased validity
> gain presumptive consent - increased ethics
