False memory and depression

The main aim of the present thesis was to investigate the effects of depression on the creation of false memories. Across four experiments the parameters of the Deese (1959), Roediger and McDermott (1995) paradigm (DRM) were manipulated. The DRM paradigm is a robust method for inducing false memories in participants and has been used widely to investigate false memory over the past 20 years (see Gallo, 2006). In the first experiment an effect of induced mood on performance in the DRM/ was established. That is, participants in an experimentally induced positive mood were more likely to falsely recognise neutral words than participants in an experimentally induced negative mood. This provided further justification for investigating mood and the creation of false memories and led onto expanding the research to participants diagnosed with depression. Experiment 2 used a recognition task with positive, negative and depression relevant word lists and compared participants diagnosed with depression and matched controls. This experiment demonstrated that participants with depression were no less accurate for true recognition than matched controls, across all word types. However elevated levels of false recognition for depression relevant words in participants diagnosed with depression was discovered. Experiment 3 used a directed forgetting task in combination with the DRM paradigm. Here it was discovered that participants diagnosed with depression were more likely to falsely recall the critical lure if they were directed to forget the related word list, significantly more so than matched controls. In addition participants diagnosed with depression were significantly more likely to recall the critical lure later in the recall sequence than matched controls under forget instructions only. The final empirical study investigated personal relevance and arousal of the particular words and lists used. Participants diagnosed with depression produced lowered levels of true recognition compared to non- depressed matched controls, but no significant difference between false recognition levels was found. There was a trend towards mood congruent effects however, where participants were more likely to misidentify depression relevant critical lures if they were diagnosed with depression. Overall, participants were also more likely to correctly and falsely recognise words if they were negatively valenced. The over arching conclusions of the research conducted within this thesis are that participants with depression are not necessarily displaying global deficits in terms of memory production, however their memory traces are vulnerable to certain manipulations of experimental design, particularly for tasks that require greater levels of cognitive control. In addition, it appears that mood congruent words and concepts may be more vulnerable to false memory errors in participants diagnosed with depression.EThOS - Electronic Theses Online ServiceGBUnited Kingdo