INFLUENCE OF AFFECTIVE WORDS ON LEXICAL DECISION TASK IN MAJOR DEPRESSION

In cognitive science, lexical decision task is used to investigate vis ual word recognition and lexical access. The issue of whether or not i ndividuals who are depressed differ in their access to affectively lad en words and specifically to words that have negative affect was exami ned. Based on some aspects of the Resource Allocation Model (Ellis), i t was postulated that patients suffering from depression take more tim e to recognize items from an affective-loaded list. In order to compar e their behavior in a lexical decision task, patients suffering from d epression and healthy controls were studied. We hoped to find an inter action between the mood state of subjects and the categories (affectiv e or neutral) of words. Two groups of right-handed adults served as su bjects in our experiment. The first group consisted of 11 patients suf fering from depression (mean age: 40.2; sd: 6.8). All of this group me t the DSM-III-R and the Research Diagnostic Criteria for major depress ive disorder. Severity of their disease was rated using the 24-item Ha milton Depressive Rating Scale. All patients suffering from depression were without psychotropic medication. The control group was composed of 24 subjects (mean age: 32.7; sd: 7.9). A depressive word-list and a neutral word-list were built and a computer was used for the lexical- decision task. A longer reaction time to detect the non-word stimuli ( F1,33 = 11.19, p < 0.01) was observed with the patients by comparison to the normal subjects. In the analysis of the word stimuli, a group b y list interaction (F1,33 = 7.18, p < 0.01) was found. Either with the neutral (F1,33 = 7.01, p < 0.01) or the affective (F1,33 = 8.60, p < 0.01) stimuli the patients evidenced a longer reaction time but the af fective list increased the delay to response only in the patients (F1, 33 = 9.16, p < 0.01). Furthermore, the adjustment of the effect of wor d stimuli with that of the non-word stimuli indicated that the depress ed patients were significantly slower than the control subjects only w ith the affective list (F1,31 = 10.34, p < 0.01) since they responded slower to that list in comparison to the neutral words (F1,32 = 8.19, p < 0.01). This study indicates that in the cognitive organization of individuals suffering from depression, information may be processed di fferently than in the nondepressed organization.