Influence of affective words on lexical decision task in major depression

In cognitive science, lexical decision task is used to investigate visual word recognition and lexical access. The issue of whether or not individuals who are depressed differ in their access to affectively laden words and specifically to words that have negative affect was examined. Based on some aspects of the Resource Allocation Model (Ellis), it was postulated that patients suffering from depression take more time to recognize items from an affective-loaded list. In order to compare their behavior in a lexical decision task, patients suffering from depression and healthy controls were studied. We hoped to find an interaction between the mood state of subjects and the categories (affective or neutral) of words. Two groups of right-handed adults served as subjects in our experiment. The first group consisted of 11 patients suffering from depression (mean age: 40.2; sd: 6.8). All of this group met the DSM-III-R and the Research Diagnostic Criteria for major depressive disorder. Severity of their disease was rated using the 24-item Hamilton 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 by list interaction (F1,33 = 7.18, p < 0.01) was found.