Stealing the past: Disputed memories in twins

Abstract

This thesis investigated a new false memory phenomenon: disputed memories, in which two people dispute ownership of a memory. For example, in one case two twins recalled being sent home from school for wearing too short a skirt although only one of them was actually sent home. The first study compared twins' ratings of disputed and non-disputed memories and found that disputed memories were rated significantly higher on a number of phenomenological properties thought to be central to recollection. Study 2 used the cue-word technique in an attempt to elicit disputed memories in a naturalistic way. Twenty sets of twins disputed a total of thirty-six events, twenty-one of which were only discovered to be in dispute during the study. In the third study non-twins were asked whether they had every experienced a disputed memory. The results suggest that they do but at a lower frequency than twins, with six of the sixty-nine participants reporting one disputed memory. Study 4 asked parents to provide brief descriptions of events from the lives of their twins to examine whether the participants would claim their co-twin's events as their own. The results suggest that they sometimes do, with two disputed memories reported from six sets of twins, but the method was somewhat unreliable as parents attributed some events to the incorrect twin. In Study 5 six sets of twins who took part in Study 1 were asked to re-rate their disputed and non-disputed memories after a two-year delay. The results suggested that disputed memories may have some quality that renders them less susceptible to decay over time as ratings for disputed memories on all of the scales remained relatively stable whilst ratings for non-disputed memories were significantly lower on re-test. Overall, results from the five studies suggest that disputed memories represent a new kind of confabulation that is relatively common amongst twins. A number of existing theories of autobiographical memory, such as source monitoring, unconscious plagiarism and imagination inflation, offer some insight as to what factors may be involved in their creation.