Researchers have thought that a key aspect of depression is that people focus on the negative, but a line of research presented at APA's 2004 Annual Convention by Stanford University psychology professor Ian Gotlib, PhD, is countering and refining that idea.
Studies over the last four years by Gotlib and his colleagues collectively show that while clinically depressed people may initially attend to negative material, they quickly blunt their response to more prolonged emotional content, such as stressful situations, sad movies and series of pictures of emotional faces.
"Until about a year or so ago, I had a great, strong, consistent story to tell about depression," said Gotlib--that depressed people attend to the negative. But his findings have caused him and others to rethink that conception.
The negative attention theory
The idea that depressed people focus on the negative was in fact supported by work out of Gotlib's own lab in the 1980s using the Stroop test--in which participants are asked to name the color of a word, such as the word "yellow" printed in red ink. The idea is that people take longer to name colors when there is interference from the content--such as the name "yellow" getting in the way of giving the correct response "red."
The researchers modified this test to see whether depressed people would take longer to name the colors of negative words than the neutral or positive words. They found, as expected, that the negative meaning interfered with depressed people's reaction times. The results indicated the depressed people were focusing on the negative, Gotlib said.
However, later research found the effect disappeared once participants had recovered from depression--until the researchers manipulated the situation: When recovered participants saw a sad film before taking the Stroop test, the negative attention effect returned.
Moreover, he noted, the effects were even stronger when, instead of words, they used pictures of happy, sad, angry and neutral faces in a dot-probe test. In this task, experimenters flashed a neutral and emotional face side-by-side on a screen and then replaced them with a dot positioned in place of one of the faces. They measured how long it took participants to see the dot. As they expected, depressed people identified the dot much faster when it appeared where the sad face had been--again indicating they were paying more attention to the negative.
Rewriting the story
While this body of research seemed to be cohesive, Gotlib says new data on physiological and neurological responses to some of the same stimuli have caused him and his colleagues to re-examine their thinking.
For example, in one study, Gotlib and Jonathan Rottenberg, PhD, now at the University of South Florida, showed depressed and nondepressed people 2- to 3-minute video clips of a sad, neutral or amusing nature while measuring physiological responses such as heart rate.
They expected depressed people to show greater arousal to sad films, since they had previously paid more attention to other negative stimuli. But they found the opposite: Depressed people--even those who cried at the sad movie--showed little physiological response when compared with the control group.
In another study, Gotlib's lab used functional magnetic resonance imaging to examine depressed and nondepressed people's brain activity while they viewed the emotional faces. Again, they expected neural activation at seeing sad faces, but instead found very little reaction.
"This is no longer a story of 'Depressed people attend to negative stimuli,'" he said, but rather one of emotional "blunting." Moreover, he noted that, in the film study, depressed people who were more physiologically reactive to the film were more likely to recover than the less reactive--even when controlling for a host of factors, including symptom level and number of episodes.
"What if there's an initial response," he asked, "but then they just clamp down?"
To examine that possibility, he ran the dot-probe study again, but left the faces up for four seconds instead of just one second. The negative attentional effect disappeared.
Together, the studies indicate that while depressed people may attend at first to negative and sad elements, their brain, heart and other areas actually shut down if those elements continue to be present.
Therefore, he explained, it's possible that boosting patients' emotional engagement might be an effective depression treatment.
For information about Gotlib's Journal of Abnormal Psychology (Vol. 113, No. 2) article on this topic, see page 19 ("Depression may not entail a global tendency to attend to negative stimuli") in the September Monitor.