Date of Award

1996

Degree Type

Dissertation

Degree Name

Doctor of Philosophy

Abstract

Previous research (e.g., MacLeod & Mathews, 1990) has found that anxious individuals show an attentional bias towards negative information, but evidence for such a bias in depressed individuals is equivocal. Conversely, there are fairly consistent findings that depressed individuals display a recall bias for negative information, whereas the findings for anxious individuals are mixed. However, task demands from this research may not have allowed anxious and depressed subjects to process information to the same extent. In the present study, 15 clinically depressed, 15 clinically anxious, 16 community control, 17 mildly depressed, 19 mildly anxious, and 17 nonclinical control subjects were tested on three attentional (modified dot probe, lexical decision, and negative priming) and two memory (word recall, and word completion) tasks using positive and negative words that were related to anxiety, depression, or a control condition. Clinically anxious and clinically depressed subjects both showed that some types of negative information (e.g., anxiety related) were more accessible than positive, but others were not (e.g., depression related, control). Also, clinically depressed subjects showed a tendency to disproportionately attend to negative information in general, whereas clinically anxious subjects avoided it. However, clinically depressed subjects were found to be slower to process information, and this effect could not be accounted for by motor retardation alone. It was concluded that clinically anxious and clinically depressed individuals recognize and respond to negative information in a similar fashion, except that clinically depressed individuals are slower in general to carry out these processes. The results from the two memory tasks indicated that clinically depressed subjects show a recall advantage for negative information. Clinically anxious subjects showed a similar, but less robust pattern. On all tasks, nonclinical samples showed similar, but less pervasive robust effects as their clinical counterparts. Overall, the results suggest that anxiety and depression are characterized by similar attentional biases, except that depressed individuals are slower processors. This difference may produce divergent patterns in later cognitive processes (e.g., memory) or their products.

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