Pupillometric measures of attentional allocation to target and mask processing on the backward masking task in schizophrenia.

Allocation of attentional resources during early visual processing was investigated in schizophrenia. Pupillary responses were recorded during a backward masking task as an index of resource allocation in schizophrenia patients (n=51) and nonpsychiatric controls (n=51). Two time-linked components of pupillary response waveforms appeared to differentially index resource allocation to targets versus masks. Two patient subgroups were identified: One with normal overall pupillary responses (resource allocation), but greater allocation on mask relative to target components, and another with abnormally small overall pupillary responses and similar allocation between target and mask components. Thus, misallocation of resources to masks contributed to masking deficits in one subgroup, whereas reduced resource allocation contributed to deficits in the other. The nature of resource-related deficits can vary across schizophrenia subgroups.