Myriads of studies have been devoted to the behaviors and brain responses of the depressed individuals. Some of the previous research has examined the verbal memory of the patients, while others employed imaging techniques to investigate the brain function of the depressed group. Many studies have looked into the responses to negative and positive stimuli of the depressed. One of the studies exploring the relation between verbal memory and depression was conducted by Elderkin-Thompson and his colleagues (Elderkin-Thompson et al., 2007). In the experiment, researchers asked senior citizens with depression to perform memory and executive tests. Compared with the control group, the depressed group had trouble memorizing words and failed in the appropriate semantic clustering as a strategy for the task. In addition, the depressed group was also found to be impaired in executive function, manifested by lower scores in Wisconsin Card Sorting Test (WCST), a test unrelated to list-learning. With semantic clustering and WCST both mediating the effect, the researchers concluded that
executive dysfunction accounts for the group’s decreased verbal memory.
Besides verbal memory, processing of emotion words is another field of research targeting the depressed group (Silberman & Weingartner, 1986). In a stroop test with emotion words that was carried out on depressed and healthy subjects, both groups
showed a left lateralization of the brain when processing positive words (Herrington et al, 2010). However, in terms of negative word processing, the depressed subjects manifested a lateralization in the right dorsolateral prefrontal cortex and the right amygdale, while the control group still displayed a preference in the use of the left hemisphere. Given that the right amygdala is in charge of rapid arousal to emotions, whereas the right dorsolateral prefrontal cortex is associated with responses to negative affections and withdrawal behaviors, the abnormal activation of these two areas might explain the inclination of negative thoughts for depressed individuals.
Moreover, biological and environmental factors both contribute to the emergence of depression. Nemeroff (1999) has proposed a stress-diathesis hypothesis, asserting that life experiences and inborn disposition render depressive disorders. On the one hand, abused or neglected individuals are highly prone to major depressive disorder. On the other, one-third of depressed patients are found to possess genes which upset the secretion of the brain-derived neurotropic factor (BDNF), a substance which helps the growth of neurons. Therefore, these patients are believed to be vulnerable to stress (Arden & Linford, 2009).
The correspondence between depression and ambiguity priming is also explored through the use of sentences as experiment materials (Lawson & MacLeod, 1999). By
dividing subjects according to their score rating on Beck Depression Inventory (BDI), a measure of depression by self-reflection, the researchers had participants read
ambiguous sentences paired with positive or neutral target words. Countering to one’s intuition, the high BDI group did not show any naming facilitation for negative words.
In fact, they were disposed to reduce interpretations on ambiguous prime sentences. On the contrary, it was the low BDI group that exhibited an increasing tendency to impose more negative interpretations of the ambiguous sentences. The common concept of negative bias in depressed individual was thus challenged in this paper.
Studies described previously have placed their focus on the depressed individuals’
brain reaction to or processing of language rather than examined the depressed persons’
use of language as the product of their mental activity. The patients’ linguistic
expression provides a unique window into the mind, not only serving as a medium for conveying thoughts and feelings, but also presenting essential diagnostic clues about the mental illness one possesses. For instance, with the aid of machine learning techniques and a computerized speech analysis program, Bedi and colleagues (Bedi et al., 2015) have been able to successfully identify and predict future onset of psychiatric illness in youths, depending on various linguistic features in the young individuals’ speech, such as semantic coherence, length of phrase, and use of determiners. Results indicated that
persons who later developed psychosis displayed loss of flow in between the meaning of sentences, produced shorter phrases, and used fewer determiner words such “that”,
“what”, and “which”.
Moreover, as regards dysphoria, which can accompany depression, Rude, Gortner, and Pennebaker (2004) studied the self-revelation essays on college life written by dysphoric and healthy individauls. Utilizing the Linguistic Inquiry and Word Count (known as “LIWC”) text analysis program (Pennebaker & Francis, 1996; Pennebaker, Francis, & Booth, 2001), the researchers concluded that, in comparison to the
non-dysphoric group, dysphoric subjects produced more negative emotion words and used more first-person pronouns to refer to themselves.
In terms of the linguistic behaviors of persons with clinical depression, Andreasen and Pfohl (1976) have examined and compared several aspects of language between patients with depression and those with mania. With the employment of
psycholinguistic methods, the findings suggested that the depressed persons exhibited more frequent use of state of being verbs, descriptive adverbs, personal pronouns, and the pronoun “I”. Furthermore, using content analysis, it was found that the speech of the depressed patients showed a tendency to be more abstract and devoted extensive
attention to the self. Identical to Andreasen and Pfohl’s findings on the use of pronoun
by depressed persons, Dönges (2009) also reported that celebrities and published poets who felt depressed or possessed self-harm ideation demonstrated more frequent use of the first-person singular, which might indicate excessive focus on the self and alienation from other people at the same time.
The depressed individuals’ production of language has been probed into through experiment approaches. In Alison and Burgess (2003), healthy and depressed subjects participated in word association tests with positive, neutral, and negative lexical items as stimuli. The subjects’ responses were measured by Hyperspace Analogue to
Language, a model which computes the range of word contexts. The findings indicated that the depressed group generated negative words in a shorter length of texts and tended to use words with a more negative connotation.
Discourse analysis is yet another approach whereby researchers explore the linguistic cues displayed by the depressed community. Based on discourse analysis, Drew and coworkers (Drew, Dobson & Stam, 1999) examined the interviews given to sixteen major depression patients on the topic of experiences of the illness. Countering to one of the DSM diagnostic criteria, which describes the patients’ symptoms as feelings of unnecessary guilt or self-worthlessness, results of the research implied that the depressed interviewees consciously refused to be blamed for their ill condition and
presented their self-image as valuable.
Much research has been conducted to investigate the brain activity of the
depression patients. Moreover, it is established that studies on language and depression provide pathological framework and diagnostic basis for depression (Fitzgerald et al., 2008; Henry & Crawford, 2005), which also aid the psychotherapies of the patients (Iakimova et al., 2009). Nevertheless, the actual linguistic production-- for instance, what kinds of words these patients tend to use, or what topic they usually talk about in discourse-- requires further exploration. Therefore, this paper intends to identify and analyze the discourse themes and lexical items crucial to and frequently occurring in the groups of depressed people in professional and peer-patient contexts.