Depression: A Breakdown of Perceptual Defence?

SummaryThe effect of depressed mood on the tachistoscopic recognition of neutral/unpleasant words was investigated in a group of 18 depressed inpatients and in 17 normal controls. A 50% recognition threshold for 30 neutral words was calculated for each subject, in order to exclude the effects of depressive slowness on the experimental task. Each subject was tachistoscopically presented with a series of experimental words (30 neutral/30 unpleasant) at his 50% level, and the ratio of neutral to unpleasant words recognised calculated. Depressed subjects tended to recognise a higher ratio of unpleasant to neutral words.

Perception of Memorized Words and Nonwords

In this experiment we tried to explain why a word is perceived more accurately than a nonword. We compared the accuracy of the tachistoscopic recognition of words with memorized words and of nonwords with memorized nonwords. We used the method of the critical interstimulus interval (Turvey, 1973). The results showed that the over-all performance was better in the word conditions than in the nonword conditions, but the influence of the memorizing factor was virtually nonexistent. This is in contradiction with two proposed hypotheses, the “feature redundancy theory” because the memorizing factor was not significant and Massaro's (1973) assumptions that the difference between words and nonwords is due to redundancy. Although words and nonwords were equated for redundancy, there remained a difference in processing time. Words and nonwords seem to be processed in essentially different ways. The word advantage seems to be dependent upon the subjects' strategy to consider the presented words as a whole.