Associations between phenomenal and objective aspects of concentration problems in depressed patients.

The paper explores a distinction between different kinds of lapse of concentration in depressed patients. The strategy is to begin with the phenomenological distinction between the mind (a) 'wandering' on to something else or (b) going 'blank'. Blanking, but not mind-wandering, is associated with longer planning times on the 'Tower of London' task. In contrast, mind-wandering but not blanking, is associated with poor memory for prose, at least under ordinary processing conditions. Different phenomenal forms of concentration problem thus have different task performance correlates. A tentative formulation is offered in terms of Shallice's model of the regulation of attention. Mind-wandering is seen as a problem of 'contention scheduling', and blanking as the result of generalized inhibition by the Supervisory Attentional System. It is evident that not all performance deficits in depression can be attributed to the cognitive capacity taken up by competing thoughts.