Cognitive neuroscience of false memory: the role of gist memory

Abstract

This thesis explores the role of gist memory and gist representation in the formation of false recognition, specifically in the Deese, Roediger and McDermott Paradigm. We found that normal individuals displayed a range of susceptibility to false recognition and true recognition and this was related to their scores on both the Autism Spectrum Quotient and the Toronto-Alexithymia Scale. More ‘male-brained’ participants exhibited less susceptibility to false recognition but also less veridical recognition. The reverse was true for more ‘female-brained’ participants. The idea of false recognition and gist memory lying along a continuum was further emphasised by work on individuals with Autism Spectrum Disorder. We found they were less susceptible to false recognition but also produced less veridical recognition. We also found differences in performance between two groups of autism individuals who also differed in age. The results of further manipulations using both picture and word paradigms suggested that gist memory could be improved in younger individuals with autism. We also examined a patient group with Functional Memory Disorder using the DRM paradigm and a confabulation task and found them less able to produce true recognition in the DRM compared with a control group. Their memory impairments could not be attributed to depression since none were clinically depressed, so we suggested that they represent the tale end of impairment to gist memory. We also explored gist memory in a patient with dense anterograde amnesia who showed reduced true recognition and a tendency to reduced false recognition, but through manipulation of the stimuli using word and pictorial material she could perform like controls due to improved item-specific discrimination. A new face recognition paradigm was also tested in which she showed a tendency towards increased false recognition in comparison with controls. Finally, we suggest the use of the DRM paradigm as a test for memory malingering since we found participants could not replicate the performance of amnesia patients without a cost in their response latencies. This is discussed through the case study of GC a man suspected of exaggerating his memory symptoms.