Working Memory Impairment of Individuals with Depressive Spectrum Disorders:The Performances on N-Back Tasks Using Emotion-Valenced Verbal and Nonverbal Stimuli

• Main Authors: De-Yao Tzeng, 曾德耀
• Other Authors: 陳淑惠
• Format: Others
• Language: zh-TW
• Published: 2007
• Online Access: http://ndltd.ncl.edu.tw/handle/09178170022148439158

碩士 === 國立臺灣大學 === 心理學研究所 === 95 === It has been often noted in literature that depressive individuals may suffer from broad deficits/bias in several areas of cognitive functions, which may be possibly due to the dysfunctions of working memory. Incorporated the possible moderators of working memory dysfunctions and/or impairments with the conception of depressive spectrum and mood-congruent memory, the main purpose of the present study was to investigate the impairment/bias of working memory of individuals with depressive spectrum disorders using N-Back task with verbal and nonverbal emotion-valenced stimuli. Specifically, the present study examined: 1) the main effect of depression severity; and 2) the interaction effects between depression severity and working memory loadings as well as between depression severity and the valences of stimuli. The present study includes two sub-studies. Study-I recruited the students of the National Taiwan University as samples who were assigned to depressive group (n = 23), dysphoric group (n = 25), and normal control group (n = 32) based on the diagnosis of MINI and BDI-II scores. The demographic and other relevant variables such as age, education level, VIQ, PIQ, and FSIQ were controlled. The Study-I, with a 3 × (3 × 3) mixed design, consisted of N-Back experiment One (verbal version) and experiment Two (nonverbal version). In that, the within-group independent variables included valences of stimuli (positive, neutral, and negative) and working memory loadings (0-Back, 1-Back, and 2-Back). The dependent variables were accuracy and reaction time. Study-II recruited clinical depressive patients (n = 18) as samples. The Study-II, with a (3 × 3) within group design, consisted of N-Back experiment One (verbal version) and experiment Two (nonverbal version). The results of Study-I, both verbal or nonverbal experiments, while indexed by accuracy, showed the main effects of working memory loadings and valences of stimuli, the interaction effects of working memory loadings with valences of stimuli and with depression severity. While indexed by reaction time, the results of Study-I revealed the main effect of working memory loadings and the interaction effects of working memory loadings with valences of stimuli and with depression severity. Differently, the results of Study-II showed the only main effect of working memory loadings in response to verbal or nonverbal stimuli. The discussion of the present study, whether the dependent variables were accuracy or reaction time, there were significant main effects of working memory loadings, indicating of successful manipulation of the N-Back task for loading of working memory. For clinical patients, neither 0-Back nor 1-Back was effortful-enough task; however, 2-Back appeared to be an effortful-enough task. The present study partly supported the mood-congruent memory, but there were opposite trends about sad and happy stimuli in verbal and nonverbal experiments. Finally, we discussed the contributions and clinical applications of the present study, addressed the possible limitations, and provided some approaches to carry on further researches.