PUPILLARY RESPONSES INDEX OVERLOAD OF WORKING-MEMORY RESOURCES IN SCHIZOPHRENIA

The authors examined the hypothesis that schizophrenia patients have r educed availability of working memory resources by using pupillary res ponses as an index of resource overload. Pupillary responses were reco rded during a verbal working memory task (digit recall) in 24 schizoph renia patients and 32 normal controls. Pupil size increased with incre ased processing load (digit-span length) but changed little or decline d when processing demands exceeded available resources (overload). The schizophrenia patients showed impaired digit recall and abnormally sm all pupillary responses during digit presentation only in the higher p rocessing load conditions, but they shelved abnormally small pupillary responses during digit retrieval in all processing load conditions. T he results suggest reduced availability of slave store and central exe cutive working memory resources in schizophrenia. This study serves as an example of how pupillography methods can be used to test current h ypotheses regarding overload of cognitive capacities in schizophrenia patients.