Prevailing theory suggests that those with depression focus on images and words relating to sadness and loss. However, new research published in the September Journal of Abnormal Psychology (Vol. 113, No. 2) finds that such tendencies may differ across individuals with the disorder. Some depressed people initially orient toward negative information, while others initially pay equal attention to negative and positive stimuli but encode and remember negative information more efficiently, say those who conducted the study.
Using three common measures of attention and recall--the self-referential encoding and incidental recall task (SRET), the emotion Stroop task and the emotion face dot-probe task--Stanford University psychologist Ian H. Gotlib, PhD, and his collaborators tested 88 people diagnosed by the Structured Clinical Interview for the Diagnostic and Statistical Manual of Mental Disorders (Fourth Edition) as having major depressive disorder, as well as a control group of 55 adults with no history of psychiatric disorders.
First, the participants completed the SRET, in which they read a list of words and rated each as self-descriptive or as not self-descriptive. After an unrelated task, the volunteers then recalled as many endorsed words as possible. All depressed people tended to endorse more negative than positive words, but only some depressed people showed a negative attentional bias, remembering more negative words such as loneliness and despair than the other depressed participants.
Second, the researchers employed the emotion Stroop task to measure the tendency of depressed people to initially focus on negative words. Participants read a list of differently colored negative, positive and neutral words, and named the hue of each word's letters. Those depressed people who attended closely to the meaning of the negative words took longer to name the colors of those words--a phenomenon known as interference, say researchers.
In the third test--the emotion face dot-probe--participants watched a computer screen that initially showed a pair of photographs, one picturing a person showing a neutral emotion and the other showing the same person looking downcast. After one second, the computer replaced the pictures with a single dot, either on the right or left side of the screen. Study volunteers then pressed a button indicating which side of the screen the dot occupied. The depressed people who attended more closely to sad faces responded more quickly to dots that appeared on the same side of the screen as the sad faces.
The researchers expected to find a general tendency for depressed people to focus on negative words and images, but they found no correlation between the different measures.
"There does not seem to be this broad attentional bias that cognitive theories hypothesized," says Gotlib.
Instead, he suggests that psychologists replace the idea of a global negative attentional bias with finer-grained distinctions, such as the initial orienting to sad stimuli as measured by the dot probe test versus some people's impaired ability to ignore irrelevant negative stimuli, as measured by the Stroop test.
If researchers can show these differentiations, therapists may eventually be able to target a patient's particular cognitive biases, says Gotlib.
"A therapist may want to focus on how one person encodes negative information, but another [client] may need to change the way [he or she] recalls events and situations."