The Hyperfocusing Hypothesis: A New Account of Cognitive Dysfunction in Schizophrenia

Abstract

Impairments in basic cognitive processes such as attention and working memory are commonly observed in people with schizophrenia and are predictive of long-term outcome. In this review, we describe a new theory-the hyperfocusing hypothesis-which provides a unified account of many aspects of impaired cognition in schizophrenia. This hypothesis proposes that schizophrenia involves an abnormally narrow but intense focusing of processing resources. This hyperfocusing impairs the ability of people with schizophrenia to distribute attention among multiple locations, decreases the number of representations that can simultaneously be maintained in working memory, and causes attention to be abnormally captured by irrelevant inputs that share features with active representations. Evidence supporting the hyperfocusing hypothesis comes from a variety of laboratory tasks and from both behavioral and electrophysiological measures of processing. In many of these tasks, people with schizophrenia exhibit supranormal effects of task manipulations, which cannot be explained by a generalized cognitive deficit or by nonspecific factors such as reduced motivation or poor task comprehension. In addition, the degree of hyperfocusing in these tasks is often correlated with the degree of impairment in measures of broad cognitive function, which are known to be related to long-term outcome. Thus, the mechanisms underlying hyperfocusing may be a good target for new treatments targeting cognitive deficits in schizophrenia.

Keywords: ERPs; attention; attentional capture; fMRI; useful field of view; working memory.

Fig 1.

Five experimental paradigms that provide evidence of hyperfocusing in people with schizophrenia (PSZ). (A) Change detection/localization task used to measure visual working memory capacity. (B) Contralateral delay activity (CDA) experiment. (C) Results of an fMRI experiment using a change detection task like that shown in (A). The left side shows the region of posterior parietal cortex in which PSZ and healthy control subjects (HCS) differed in terms of the function relating activity to the number of items stored in memory, and the right side shows the signal change (relative to baseline) within this region for each set size. (D) Useful field of view experiment. Participants report whether the central object is a car or truck and the location of the peripheral object. The timing of a mask that follows the targets is adjusted to find the 75% accuracy point (the threshold). (E) Spatial cuing experiment in which a central cue directs attention to between one and 4 potential target locations.

Fig 2.

(A) Double oddball paradigm. (B) Suppression of sensory-evoked P1 when attention was directed away from a given location. A larger bar indicates greater suppression (smaller P1 amplitude). (C) P3b probability effect (rare minus frequent) for stimuli in the ignored region, which indicates the amount of cognitive processing resources devoted to irrelevant stimuli. Here, a larger bar reflects a failure to suppress processing in the to-be-ignored region.

Fig 3.

Three experimental paradigms in which people with schizophrenia (PSZ) exhibit greater capture of attention to stimuli that partially match a relevant color. (A) When participants are asked to detect a specified color (eg, red) at fixation, a target-color distractor at a lateral location elicits an initial shift of attention (indexed by the N2pc component). In healthy control subjects (HCS), this is rapidly followed by suppression of the target-color distractor (indexed by the P_D component), but attention remains focused on the target-color distractor in PSZ. (B) When participants search for an item of a particular color (eg, red), a distractor captures attention when it matches this color, impairing target discrimination accuracy, and this is exaggerated in PSZ. (C) When participants monitor a rapid stream of foveal letters for a target of a particular color (eg, red), a flanker of this color captures attention, especially when the flankers are close to the target. PSZ show more of this capture than HCS when the flankers are close to the target, but less when the flankers are farther away. Neither group exhibited distraction by a neutral-colored distractor (not shown here).