Investigating location-based and object-based inhibition of return in patients with schizophrenia

Inhibition of return (IOR) is a well-observed effect in attention orienting tasks. People are slower and/or less accurate to detect a target that appeared at a recently attended location than a novel one. Sometimes inhibition can slow the return of attention to a particular object (object-based IOR). Object-based IOR has been demonstrated in both dynamic and static displays. In static displays, presumably object-based IOR can be additive to location-based IOR. Research investigating IOR in patients with schizophrenia have yielded conflicting results. To date no study has examined object-based IOR in patients with schizophrenia. The current study used a cue back to fixation exogenous cuing paradigm with static displays to investigate both location-based and object-based IOR in patients with schizophrenia and healthy controls. The results showed that significant location-based IOR occurred in both groups, with reduced magnitude of IOR in the patient group than in the control group. No additive object-based IOR was observed in either group. Furthermore, IOR in patients did not correlate to their age, education, and symptom severity. However, it is possible that IOR is related to their general cognitive function. Overall, the results support the hypothesis that location-based IOR plays a much more essential role in the inhibitory mechanisms that facilitate visual search.