Deficits in Effortful Control

Effortful processing requires both a reason to do so and the capacity to do so (Barrett et al., 2004). With respect to the former, Beevers (2005) held that a negative association triggers an effortful correction only if the association is unexpected, and thus calls for attentional resources to sort things out. However, a negative association would be unexpected only if the person’s explicit self-view was positive. Inasmuch as depressed people typically describe themselves negatively on explicit self-view indices (Abramson et al., 2002), a negative implicit association would generally not violate their expectancies and would not trigger effortful override. Thus, a prompt for effortful processing may often be lacking.¹¹

Other views of depression also emphasize the idea of cognitive control deficits. Hertel (2000), for example, viewed negative thoughts, biased processing of emotional information, and ruminative thinking in depression as automatic patterns activated by negative mood states. Those patterns dominate unless overridden by effortful cognitive control (e.g., Hertel & Rude, 1991).

Deficits in effortful cognitive control can yield diverse outcomes. In some cases, it can keep the person from moving on. For example, depression has been related to impaired shift in behavior after error feedback (Compton et al., 2008; Holmes & Pizzagalli, 2007). Similarly, there is evidence that depressive rumination interferes with disengaging from previously relevant but no longer relevant information, as in task switching (Whitmer & Banich, 2007).

In other cases, deficits in effortful cognitive control can keep the person from remaining task focused. Thus, there is also broad evidence of mental restlessness and distractibility among depressed persons. Smallwood and his colleagues have repeatedly found that depression relates to mind wandering across diverse tasks (for a review, see Smallwood, O’Conner, Sudberry, & Obonsawin, 2007; see also Smallwood & Schooler, 2006). Greater mind wandering has also been linked to lower levels of working memory capacity (Kane et al., 2007). The distraction of mind wandering among depressed persons interferes with completion of planful activities.

Other phenomena related to depression also fit this view of executive control deficits (see also Levin et al., 2007). For example, depression is well known to be associated with autobiographical recall of memories that are very general in character rather than specific (Williams et al., 2007). A recent set of studies has yielded convincing evidence that this effect stems from executive control deficits (Dalgleish et al., 2007).

There is also evidence that depressed persons have trouble ignoring negative information (Frings, Wentura, & Holtz, 2007) and disengaging from negative information once attended to (Caseras, Garner, Bradley, & Mogg, 2007; Joormann & Gotlib, 2008; Joormann, Yoon, & Zetsche, 2007). Several measures have been developed to assess the capacity to effortfully suppress attention to negative material. Examples are the emotion Stroop task, measures of negative priming (Joormann, 2004; Wentura, 1999), and attention tasks with a long stimulus duration (Derryberry & Reed, 2002; Vasey, 2003, cited in Lonigan, Vasey, Phillips, & Hazen, 2004). Depressed persons show negative biases on the emotion Stroop, negative priming tasks, and attention tasks with long stimulus durations (Goeleven, De Raedt, Baert, & Koster, 2006; Gotlib et al., 2004; Gotlib & Krasnoperova, 1998; Joormann, 2004). All of this represents further evidence of deficits among depressed people in effortful cognitive control, in this case, specifically effortful control over thoughts.

Дата добавления: 2015-11-14