Organisms face multiple adaptive challenges, many of them simultaneously, and they must have adaptations that allocate attention and cognitive resources to them. Negative emotions are thought to have evolved, at least in part, for this purpose (Alexander, 1986; Barlow, 2002; Buss, 2000; Ohman, Flykt, and Esteves, 2001; Thornhill and Thornhill, 1989). Specifically, the effect of negative emotions on attention is thought to be analogous to the influence of physical pain on attention. Physical pain draws attention to problems that are causing, or threatening to cause, physical damage to the body, such as the pain that one feels when one inadvertently puts one’s hand on a hot surface (Eccleston and Crombez, 1999; Wall, 2000). Similarly, negative emotions are thought to have evolved to draw attention to important problems in the environment (often of a social nature) that had an important impact on fitness and could be fixed or ameliorated with attention (Alexander, 1986; Thornhill and Thornhill, 1989).
Control-process views of emotion suggest that they are related to progress or frustration in finding solutions to problems or meeting goals (Carver, Lawrence, and Scheier, 1996; Carver and Scheier, 1990). Negative emotions are elicited when one has not found a solution to a problem or one is not making satisfactory progress towards a goal, and the emotion draws attention to the task of finding a solution. Conversely, positive emotions are elicited when one has found a solution or is making satisfactory progress towards a goal, and the emotion keeps attention focused on the adaptive course. For instance, courtship is emotionally painful when unrequited, and attention is directed to solving the problem of successfully wooing the desired partner. However, positive emotion is elicited when the partner responds positively to the courtship, and attention and behavior stays focused on the same course, at least until progress towards the mating goal becomes unsatisfactory. Thus, the valence of emotion reflects whether or not progress towards a goal or a solution is being frustrated (Carver et al., 1996; Carver and Scheier, 1990).
There are many different negative emotions—e.g., anger, anxiety, disgust, fear, jealousy—and they presumably evolved to influence attention in different ways. In this paper, we focus on the attentional function of depression or depressed affect, which is an emotion characterized by negative affect and low arousal.
Although clinical depression is often assumed to be qualitatively different than subclinical forms, explicit tests of this assumption have found that depressed affect is better characterized by a single dimension that varies continuously in intensity and duration (Aggen, Neale, and Kendler, 2005; Krueger and Markon, 2006). For instance, depressive symptoms vary continuously in epidemiological samples (Hankin, Fraley, Lahey, and Waldman, 2005), and the degree of psychosocial impairment covaries linearly with the number of depressive symptoms (Kessler, Zhao, Blazer, and Swartz, 1997; Sakashita, Slade, and Andrews, 2007). We therefore use the terms depressed affect and depression to refer to a single continuum that varies from transient sadness to chronic, severe, clinical depression.
There is abundant evidence that depression influences attention. People with clinical or subclinical depression tend to report persistent ruminations about important problems in their lives (Lyubomirsky, Tucker, Caldwell, and Berg, 1999). Indeed, people with greater levels of depression tend to ruminate more and are less easily distracted from their ruminations (Just and Alloy, 1997; Lam, Smith, Checkley, Rijsdijk, and Sham, 2003; Nolen-Hoeksema and Morrow, 1991; Schmaling, Dimidjian, Katon, and Sullivan, 2002). Attention is a limited resource (Kahneman, 1973), with one implication being that as attention becomes more focused on one problem, fewer cognitive resources are available for other problems. Further evidence of depression’s influence on attention thus comes from the fact that depressives’ ruminations interfere with their ability to concentrate on other things. For instance, when people come into a psychological testing situation with clinical or subclinical depression, their ruminations interfere with their ability to focus on cognitive tasks and reduce their performance (Lyubomirsky, Kasri, and Zehm, 2003; Watkins and Brown, 2002; Watkins and Teasdale, 2001; Watkins, Teasdale, and Williams, 2000). Such research suggests that depression focuses attention on the problems that caused the episode, so much so that it interferes with people’s ability to focus on other things. Put another way, one of depression’s effects is to focus attention and reduce distractibility.
Depressives’ focused attentional state can affect how they process information. Research on pre-existing and experimentally induced mood indicates that depressed affect promotes an analytical processing style (Ambady and Gray, 2002; Au, Chan, Wang, and Vertinsky, 2003; Bless, Bohner, Schwarz, and Strack, 1990; Bless, Mackie, and Schwarz, 1992; Braverman, 2005; Edwards and Weary, 1993; Forgas, 1998; Gasper, 2004; Gasper and Clore, 2002; Hertel, Neuhof, Theuer, and Kerr, 2000; Schwarz and Bless, 1991; Semmler and Brewer, 2002; Sinclair, 1988; Sinclair and Mark, 1995; Storbeck and Clore, 2005; Yost and Weary, 1996). Analytical reasoning involves dividing a complex problem into smaller, more manageable components, where each is studied in turn. To arrive at the solution to the whole, the solution to each component must be maintained in memory while processing on the next component takes place. Analytical reasoning therefore requires the use of working memory, which holds information in a highly active state because it is crucial to ongoing processing (Baddeley, 1996).
The Raven’s Advanced Progressive Matrices (RAPM) is considered one of the best measures of nonverbal analytical reasoning ability (Carroll, 1993). Each item is a spatial pattern completion task in which one of eight choices correctly completes a two-dimensional visual array, and test items become progressively more difficult. The difficulty of test items increases, in part, because the number of elements in the array increases and the rules for how they vary across the array can be different for each element (Carpenter, Just, and Shell, 1990). The rule for each element must be ascertained independently, so once subjects figure out the rule for how one element varies across the array, they must keep the solution in their working memory while they figure out the rules for the remaining elements. The number of elements that must be analyzed and held in working memory varies from 1 to 5, and the proportion of people getting a test item correct is negatively related to the number of elements that must be analyzed (Carpenter et al., 1990).
Current research indicates that analytical tasks with high working memory loads, such as the RAPM, are attentionally demanding because they leave little room for attention to wander (Kane and Engle, 2002). For instance, performance on the RAPM is highly correlated with the ability to resist distractions under attentionally demanding conditions, and the relationship is mediated by differential activity in areas of the brain known to be involved in attentional control (Gray, Chabris, and Braver, 2003).
In summary, depressed affect focuses attention on problems, and it promotes an analytical processing style. Because analytical reasoning requires focused attention, it seems reasonable to hypothesize that depressed affect may promote an analytical processing style by its attention-focusing effects.
We suggest that depressed affect evolved as a response to important, analytically challenging problems that could only be solved, if they could be solved at all, with an attentional state that was highly focused for a sustained period of time (Watson and Andrews, 2002). Under this hypothesis, depressed affect promotes analysis and problem-solving by focusing attention on the problem and reducing distractibility.
If depressed affect is a response to analytically challenging problems, then a task such as the RAPM should be able to induce depressed affect in people with low levels of depression. Established methods for inducing depressed mood involve having subjects listen to sad music or watch sad movies, giving them negative feedback about their performance on tasks, having them apply self-referent statements to themselves (e.g., “I feel a little down today”, “I wish I could be myself, but nobody likes me when I am”) (Seibert and Ellis, 1991), and so on (Westermann, Spies, Stahl, and Hesse, 1996). There is also substantial evidence that stressful life events can induce depression (Kendler, Karkowski, and Prescott, 1999). While cognitively effortful tasks are often used in methods that rely on negative feedback, the feedback is almost always fixed (i.e., even people who perform well on the task are given negative feedback) (Westermann et al., 1996). Moreover, it is failure itself, and not the nature of the task, that is assumed to elicit depressed affect. Our prediction that an analytically and attentionally challenging task can induce depressed affect, and not failure per se, is, to our knowledge, novel and untested.
There are two potential control-process mechanisms by which depressed affect could focus attention and reduce distractibility. First, depressed affect may keep attention focused on a problem in a way that is similar to the force exerted by a spring. In this analogy, the problem could be thought of as being attached to one end of the spring and attention to the other end. When the spring is compressed and relaxed, attention is focused on the problem, and the force exerted by the spring is minimized. When the spring is pulled, attention is pulled away from the problem, and the spring’s force increases. If depression’s mode of action is like the force exerted by a spring, then depressed affect should increase as attention is pulled from a focal problem, which would tend to draw attention back to the problem. Validation of the spring metaphor would suggest that, at the time of measurement, depressed affect is a marker of the degree to which attention is diverted from the problem that elicited the episode.
Alternatively, depression’s influence on attention could be more like the attractive force on a steel ball produced by a magnet. In this analogy, the “magnet” is a difficult problem (e.g., marital troubles). The attractive force that the problem generates is depressed affect, and it draws attention to the problem just as the magnetic force draws a steel ball to the magnet. Since the magnetic force is greatest when the steel ball is closest to the magnet, depressed affect should be greatest when attention is fully focused on the problem, where it tends to keep attention focused. When attention is diverted to some other problem, depressed affect will decrease, just as the attractive force on the steel ball lessens as it is pulled from the magnet. Validation of the magnet metaphor would therefore suggest that, at the time of measurement, depressed affect is a marker of the degree to which attention is focused and distractibility is reduced.
We stress that the terms magnet and spring are merely metaphors to describe the possible ways depressed affect could exert force on attention. However, we use them because they help describe the different mechanisms of action that we are hypothesizing.
According to the hypothesis, depressed affect is a response to analytically and attentionally demanding problems that may take a long time to solve. Consequently, the organism might occasionally need to interrupt processing to deal with pressing issues that require immediate attention (e.g., predators, important social problems). After the issue has been dealt with, attention must return to the core problem that caused the depressive episode. Since attention must be pulled from the core problem to be focused on the pressing issue, processing the pressing problem would be very difficult with a spring-like mechanism because a great deal of force must be expended to keep attention focused there. However, under a magnet-like mechanism, once attention was pulled away from the core problem and focused on the pressing problem, less force would be needed to keep it there. Thus, a magnet-like mechanism would be better from an engineering perspective.
To test between these two mechanisms, we measured subjects’ level of depressed affect twice. The first assessment (T1) was a baseline measure to assess the level of depression that they brought with them into the laboratory. Since depressed affect is continuously distributed in populations, people come into a psychological testing situation with varying levels of depressed affect unless pre-screening takes place. The causes of their depressive symptoms are assumed to reflect important pre-existing life issues, and we refer to this as their pre-existing depression.
Subjects completed the second assessment (T2) of depressed affect after they had been given intervention—in this case, practice questions from the RAPM. The hypothesis that depressed affect arises in response to an analytically and attentionally challenging problem predicts that subjects with low levels of pre-existing depression should experience an increase after exposure to the intervention. We were concerned that after the subjects had completed the attentionally demanding intervention, their attention would immediately relax and we would be unable to detect the emotional effect we were looking for when they took the T2 measure. So we devised the intervention’s effect to be prolonged.
The intervention was also designed to get subjects with high levels of pre-existing depression to pull their attention away from their pre-existing problems. The spring and magnet mechanisms make different predictions about how they will respond emotionally to the intervention. According to the spring metaphor, this is like pulling a spring, and depressed affect should increase. Under the magnet metaphor, however, the intervention is like pulling a steel ball away from a magnet. This should cause the level of depressed affect to decrease just as the magnetic force exerted on the ball decreases.
No comments:
Post a Comment