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Components of visual search in childhood-onset schizophrenia and attention-deficit/hyperactivity disorder
1University of California, Los Angeles 90024, USA.
Insights
Children with schizophrenia and attention-deficit hyperactivity disorder (ADHD) show slowed visual search. ADHD, not schizophrenia, involves delayed serial search initiation, with both groups exhibiting intact parallel search but impaired serial search rates.
Area of Science:
- Neuroscience
- Developmental Psychology
- Psychiatry
Background:
- Visual search impairments are noted in schizophrenia.
- The underlying mechanisms, such as search initiation delay or slow search rate, require clarification.
- Understanding these mechanisms is crucial for differentiating schizophrenia from other neurodevelopmental disorders.
Purpose of the Study:
- To investigate whether visual search deficits in schizophrenia stem from delayed search initiation or a slow search rate.
- To determine the specificity of these visual search impairments by comparing children with schizophrenia to those with attention-deficit hyperactivity disorder (ADHD) and typically developing children.
- To test hypotheses within the framework of feature integration theory.
Main Methods:
- Administered tasks assessing parallel and serial visual search in children with schizophrenia, ADHD, and controls.
- Estimated search rate using the slope of search functions.
- Measured the duration of initial search stages by analyzing the time to the first saccade.
Main Results:
- Both schizophrenia and ADHD groups exhibited elevated manual response times.
- Children with ADHD, unlike those with schizophrenia, showed delayed initiation of serial search.
- Both clinical groups demonstrated intact parallel search rates but significantly slowed serial search rates.
Conclusions:
- Visual search impairments in schizophrenia are characterized by slowed serial search rates, not delayed initiation.
- Attention-deficit hyperactivity disorder is associated with delayed serial search initiation.
- These findings highlight distinct visual search processing deficits in schizophrenia and ADHD, aiding in differential diagnosis.
Abstract:
This study tested the hypotheses that visual search impairments in schizophrenia are due to a delay in initiation of search or a slow rate of serial search. We determined the specificity of these impairments by comparing children with schizophrenia to children with attention-deficit hyperactivity disorder (ADHD) and age-matched normal children. The hypotheses were tested within the framework of feature integration theory by administering children tasks tapping parallel and serial search. Search rate was estimated from the slope of the search functions, and duration of the initial stages of search from time to make the first saccade on each trial. As expected, manual response times were elevated in both clinical groups. Contrary to expectation, ADHD, but not schizophrenic, children were delayed in initiation of serial search. Finally, both groups showed a clear dissociation between intact parallel search rates and slowed serial search rates.