OCR Core studies
Cognitive psychology: Loftus and Palmer (1974)
Reconstruction of automobile destruction
INFORMATION: Loftus and Palmer examined whether the phrasing of a question influences speed estimates.
EXPERIMENT 1 Method: Design: Lab experiment using between-participants design (different verb for each group). The
independent variable (IV) was the verb used (smashed, collided, bumped, contacted, hit). The dependent variable (DV) was the speed
estimate. Participants: 45 students (various size groups). Apparatus/materials: 7 films (5-30 seconds long) and a questionnaire
which asked participants to give an account of the accident and answer specific questions. Procedure: 1. Films presented in differing
orders to each group. 2. Questionnaire completed which included the critical speed question “About how fast were the cars going
when they [hit] each other?” Results: Highest mean speed estimate for ‘smashed’ (40.8mph) and lowest for ‘contacted’ (31.8mph)
(p<0.005). Conclusion: Phrasing affects speed estimate. The participant may not be sure if it is 30 or 40mph and the verb ‘smashed’
biases them to respond with the higher estimate. Alternatively, the question causes a change in their memory; they may ‘remember’
details that did not occur. Experiment 2 tests this.
EXPERIMENT 2 Method: Design: Lab experiment using between-participants design (different question for each group). IV was
the critical question. DV was whether participants recall seeing broken glass. Participants: 150 students (various size groups).
Apparatus/materials: 1 film less than 1 minute long (accident lasts 4 seconds) and questionnaire asking participants to describe
accident in their own words and answer questions. Procedure: 1. Film of multiple car accident presented. 2. Questionnaire completed
which included the critical speed question: 50 participants asked how fast cars going when ‘smashed’; 50 asked how fast when ‘hit’;
and 50 not asked speed question (control). 3. 1 week later, participants asked 10 questions. A randomly placed critical question asked
“Did you see any broken glass?” (yes/no answer). There was no broken glass, but it does fit with high speed accidents, so expect
participants to say yes more often with the word ‘smashed’ than with ‘hit’. Results: Mean speed estimate more for smashed
(10.46mph) than hit (8mph) (p<0.05). Probability of saying yes 0.32 for ‘smashed’, 0.14 for ‘hit’; participants did give more yes
responses and higher speed estimates for ‘smashed’.
CONCLUSION: Phrasing of a question influences recall. They propose that two types of information go into memory: one from
perception of the original event and one from external information supplied after (leading question). These merge over time, so we
experience one ‘memory’. The verb ‘smashed’ labels the event, causing a shift in memory.
Experimental design,
method & sampling
Apparatus/materials
Controls
Qualitative/quantitative
measures
Ethics
Individual/situational
explanations
Ecological validity
Confounding variables
Usefulness of research
and application to
everyday life
Generalisations
Two laboratory experiments, both between-participants. Experiments were
done using students from Washington University.
Films of car accidents and questionnaires.
This study was very well controlled. For example, in experiment 2, one group
of participants were not asked the critical ‘broken glass’ question. Good
control over variables is possible as it was conducted in a laboratory; doing
this study outside would lack control over all variables (but increase
ecological validity).
Quantitative data: estimations of car speed and perception of broken glass.
Data analysed using statistical tests (ANOVA, t-test, chi-squared test).
Qualitative data: none.
Would it be ethical to conduct this experiment in a real-life setting?
Possibly situational variables relating to demand characteristics.
Low ecological validity as it was conducted in a laboratory. There would be
differences between seeing a car accident on film and seeing it in real life
(e.g., other distractions, high emotional involvement).
Order effects controlled by random sequence of presentation of films to each
group. Demand characteristics: student participants may work out the aim of
the research.
The findings show that memory is easily distorted, which has implications for
eyewitness testimony in police statements and courts. The evidence shows
that leading questions can bias the eyewitnesses’ answers.
The participants were all students; they may not be representative of the
population as a whole.