Aims and Context
- Cognitive psychology linked to memory
- What is memory? - retention and use of prior learning. After incident EM - 3 stages: Encoding(encoding info-event+people involv. in long term memory) Storage(store info 4 a period of time) and retrieval(retrieving info from storage). Memory = probs- EWT(refers to descriptions provided by individuals who have witnesses a crime/accident.
- EWT- important are of study in cog psy + memory stud. (used as evidence in criminal trials. validity of evid. can be affected by many pyschol factors. memory of event can be altered by info gained after - concerns - reliability. 1973 - 74% convicted relied on EWT. EWT can be infl. by leading questions(asked such way - promt answer - wearing scarf? vs. What colour scarf?) contrabutes concerns with EWT (Loftus and Palmer)
- Previous studies- Marshall - 69 - found that when airforce personell knew in adavance they'd estimate the speed of a vehicle (12mph) (answers ranged 10 - 50mph). wide range of speeds - peop not good at estimating speed - susceptable to leading Q. Filmore - 71 - diff words to effect how fastwe think the vehicles were moving - smashed, hit, contacted etc.
- Aims - The aims of their resea was to investigate the accuracy or inacc of mem. .In part wanted to invetsig the effect of lead Q on estimate - speed.
- EXP 1- see if lead Q distorted the accuracy of an eyewitness recall.
- EXP 2- see if leadQ created a response bias or if alter a persons mem.
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- EXP 1 -
- 45 participants. shown 7 film clips of diff traff acc taken from films made 4 police. Film segm ranged from 5 to 30 secs.
- After each clip participants had to fill in a questionnaire. Among Q was one crit Q: How fast were the cars going when they ____ eachother. insert diff verb each time to see if imp: hit,bumped,collided,contacted, or smashed.
- The order of film clips and Q were varied.
- EXP 2 -
- This stud. inv. 150 students.
- Part 1 - particip. shown a film of multp car crash. the actual acc lasted 4 secs.
- then asked set Q inc. the crit Q about speed. particip. divided into 3 groups. G1 asked - Smashed, G2 asked - Hit, G3 not askd crit Q (controll group)
- Part 2 - one wk later particip asked 2 return, asked further Q about the filmed accident. The crit Q asked 'did you see any brken glass?'-none in the actual film.
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Findings and Conclusions
- Findings - EXP 1 - The highest mean estimated speed - Q that included - smashed - 40.8mph. Lowest est speed - contacted - 31.8 mph. collided=39.3, bumped=38.1 + hit=34.0.
- Conclusions - EXP 1 - smashed most violent word used in the questions - higest mean est speed. contacted - least viol word used- lowest mean est speed. Relation between 'strength word' and est of speed. how Q was phrased had a sig effect on a witness's answer.
- So wording of Qs does affect mem. of an even, with more severe sounding verbs = higher est. L+P suggested 2 poss reasons for the results of EXP 1. 1= Response bias - diff speed ests. occurred b/c the crit word influences or biases a persons response. 2=Mem is altered - Crit word changes a persons mem. so they 'see' the accident diff...i.e. more or less severe. t prove this 2nd point L+P tested this - would peop remember details not true?purp= see which expl was correct.
- Findings - EXP 2 - in the 'smashed' condition 16 said had seen broken glass 34 =not, in 'hit' condition - 7 = yes 43 = no, controll- 6 = yes 44=no. The results show that the verb used in the original question influenced whether the participants thought they had seen broken glass.
- Conclusions - EXP 2 - 6 in 'smashed' reported having seen broken glass - words we assoc? Fewer in hit - word not assoc? Controll slightly less but not by much - it suggests that even without post event info being suggested to us our mems. of events may not be 100% accurate.
- The results showed that the way a Q is asked can influence the answer - not due to response bias b/c all partic asked if they had seen broke glass. thi sugg lead Q altered memory of the event
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- Lab studies -
- S1 - Allow control over extran variab (location, use of vids, Q asked and so allowed L+P to change IV- DV (cause and effect). S b/c allows them to say it was defo IV that effected the DV.
- S2 - standardised procedure can be repeated as a result - s b/c makes findings more reliable. Later studies have found similar to this = Loftus and Zanni - THE broken headlight vs A broken headlight.
- S3 - using a lab exp allow L+P to vary order of film clips in exp1 and vary posit of crit Q in exp2. S b/c reduce order effects and increase internal validity.
- S4 - the info p's asked to recall was meaningful - likely to ocur in real life - S b/c results represent. of the demands of our everyday mem. so findings can be generalised to real life.
- W1 - lacks ecol vali. not stress out by it - like real life and had no personal involvement in the judgment of speed-not how usually witness events. W b/c harder to generalise to real life
- W2 - aware they were in a study - demand characteristics. but effect reduced=embedding crit Q.
- Participants- students - young? better at remembering tasks? may have diff driving exp. and so diff estimates of speed.W b/c may not be representa of gen pop. Indep grouping used - S b/c reduces demand charcteris as participants only experience one cond. so less likely to guess res purp. Only 9 ppts used in each group in exp 1 - small sample - limited representation of gen pop. Each group small so may have sim characteristics then as res perfom diff to oth group.
- Ethics- L+P not get informed cons from particps- uneth b/c cause distress. but not tell ppts aim as this make stud. meaningless + any stress= mild = no injury caused.
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- Loftus and Zanni - lab exp - show particps film foot of multip car acc. Then asked did you see A/THE broken headlight? NO BROKEN HEADLHT. particps more than twice as likely to say yes to the THE Q rather than A (17% vs. 7%). 15 % particps decieved but the finds supp L+Ps finds on t effect of misleading post-event info. impacti on mem. rela simp task - if mislead this, how much more mislead on-comple? both stud. sim same strength being contro, precise, replic.
- Loftus - lab exp - show particps slides, theft of red purse. then asked 2 read account of t theft from an alleged prof of psy. it said purse=brown. 98% of ppts correctly remem it red. color basic feature. pers who saw event more likely 2 keep orig mem. intact so contra L+Ps stud. -shows the orig L+P stud may 've lacked relev + importance to the particps + this may have contra to differ findings. easier to gen these finds to real life than L+P.
- Loftus-150 ppts-film-car acc. Aft ppts put 2 groups, each ask 10Qs bout what seen. G1 ask qs direct link with film. G2 ask same exce for 1:hw fast was white sprts car goin when it pass barn? NO BARN!. aft 1 wk ppts asked 10Qs both:you see a barn? 17.3 of G2 said yes. 2.7 of G1 said yes! resul imply tht the barn added 2 G2s mems. now incorrectl remem as part of event. Sim 2 thos who remem brok glass-supp L+Ps orig finds as orig repres of eve changed.
- Christianson+Hubinette- question 110 witns who had witn 22 gen bank robs betw them. some been onlooks in bank at t time, some bank employ who directl threaten. victs more acc in their mems. and rememb more detail about clothe and behav than bystders. means peop are gd at rememb. stressful events if direct. this contra L+Ps finds as show how real life wits recal can be acc esp when inv. .in the lab stud. no involvement. but not tell us about post event info.
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