Inhibition of Return Is Not Impaired but Masked by Increased Facilitation in Schizophrenia Patients

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Abstract

Objective:

When attention is attracted to an irrelevant location, performance on a subsequent target is hindered at that location in relation to novel, not previously attended, locations. This phenomenon is known as inhibition of return (IOR). Previous research has shown that IOR is not observed, or its onset is delayed, in schizophrenia patients. In the present study, the authors tested the hypothesis that IOR may be intact but masked by increased facilitation in schizophrenia patients. To test this hypothesis, they used a procedure that usually reduces or eliminates the early facilitation.

Method:

In the first experiment, the authors used the typical single-cue IOR task in the group of healthy adults (N = 28) and in a group of schizophrenia patients (N = 32). In the second experiment, they manipulated cue-target discriminability by presenting spatially overlapping cues and targets where the cues were more intense than the targets.

Results:

In Experiment 1, they did not find significant IOR effects in the group of schizophrenia patients, even with cue-target intervals as long as 3,200 ms. However, in Experiment 2, IOR effects were significant at the 350- and 450-ms cue-target intervals for healthy and patients, respectively.

Conclusions:

This is the first study that shows that schizophrenia patients can actually show inhibitory effects very similar to healthy controls, even when no help is provided to shift their attention away from the irrelevant location. The authors suggest that inhibition is intact in schizophrenia patients, but it is usually masked by increased facilitation.

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