Pezdek, Finger, & Hodge, (1997). Planting false childhood memories: The role of event plausibility. Psychological Science, 8, 437-441.
Introduction
In their brief review of the literature on the creation of false memories, the authors point out a distinction between planted vs. changed false event-memories. Research has shown that it is relatively easy to manipulate the details of what children remember from an experienced event (i.e., change an existing memory) via post-event suggestion (Ceci et al.). Yet Pezdek et al. do not feel that research has clearly shown that any old event can be completely planted or erased from memory. Research has shown that some college students will falsely remember being lost in the mall (Loftus & Pickrell), or that they spilled punch on the parents of the bride at a wedding they attended when they were five (Hyman, Husband, & Billings). However, Pezdek et al. state that it is inappropriate to generalize the fact that if some people will accept relatively innocuous memories as being true, that some people will also accept suggested memories of traumatic CSA as being true as well. As such, research needs to show whether there is a difference between accepting plausible vs. implausible suggestions (of course this implies that in some cases memories of abuse are implausible). So the present study is based upon the assumption that if a fabricated event is to be planted and accepted as a memory, it must be both plausible and script-relevant.
(Incidentally, some of the participants in Hyman et al.'s study would not accept the suggested memory as true because they knew that they had never been to a wedding when they were five, thus it was an implausible suggestion).
Hypothesis: "Only events that seem plausible and that one has script relevant knowledge for can be suggestively planted in memory".
Assumptions this is based upon:
-- Things deemed true are more likely to be remembered
-- Things deemed true are more easily remembered
-- Things that you already have general script knowledge for are easier to remember
Experiment 1
Catholic and Jewish school girls were asked to read five scenarios summarizing childhood events; three of the scenarios were true, and two were false. One false scenario depicts dropping the ceremonial bread during a Jewish prayer session, and the other scenario depicts following the wrong family back to the church pew after receiving communion. For Catholic participants, the communion scene was considered "Very Plausible" and the prayer scene was considered "Less Plausible", and vice versa for the Jewish participants. After reading the scenarios, the participants were asked to:
-- rate the clarity of their memory
-- rate their confidence that they could remember more if given some time
-- elaborate on the scenarios one week later
Results
They used a non-parametric
c 2 test to test the likelihood of later elaborating upon either the "more plausible" or "less plausible" event, and it was significant:
-- 10 participants elaborated upon the "more plausible" event, while only 1 participant elaborated upon the "less plausible" event
They also did a qualitative analysis and found that across participants:
-- true recall elaborations included more words
-- true recall elaborations included more idea units
-- true recall elaborations had higher clarity and confidence ratings
Conclusion: More plausible suggestions were more likely to be accepted as memories
Experiment 2
Confederate college students interviewed a younger sibling or close relative about one true event and two false events that supposedly happened to the younger sibling, when he/she was around 5, while the confederate was present. An older sibling was used as the interviewer because Pezdek et al. felt that an older sibling who was there should be viewed as a reliable and trustworthy source. The plausible false event was of getting lost in the mall, while the implausible false event was receiving an enema after suffering from constipation.
Results
3 out of 20 siblings accepted the plausible event of getting lost in the mall, no siblings accepted the implausible event of receiving an enema.
They suggested that so few participants accepted either suggested event as being true because the confederate-interviewers were not trained well enough in using suggestive techniques.
I would argue, however, that the results turned out as they did because an older sibling is not a reliable source of such implausible information-- my older siblings love to tease me, as such it is completely plausible to me that they might try to get me to believe something that was false!
Conclusions and things to think about
The authors state that the finding:
Plausible suggested events are more likely to be accepted as true memories than are implausible suggested events confirms their hypothesis -- "Only events that seem plausible and that one has script relevant knowledge for can be suggestively planted in memory".