Speed of information processing in traumatic brain injury: Modality-specific factors

Objective: To assess speed of information processing by two serial addition tests (one visual, one auditory) in individuals with moderate-to-severe tr aumatic brain injuries (TBIs) and in a healthy, normal control group (NC). The tasks were designed to equate and control for accuracy of performance a cross the TBI and NC groups, thus allowing for quantification of informatio n processing speed. Design: Performance across groups and tasks were compar ed using 2 x 2 repeated measure analyses of variance (AOVAs). In addition, each individual's processing speed was used to adjust rate of stimulus pres entation on a subsequent "rehabilitation" trial to determine further whethe r this adjustment equated accuracy of performance. setting: Rehabilitation hospital. Patients: 22 outpatients with moderate-to-severe TBI (6 women, 16 men; mean age = 34.6 years; duration of loss of consciousness = 22.6 days) and 20 age- and education-matched healthy controls. Results: Processing sp eed was slower in TBI subjects, relative to controls and was significantly related to measures of executive functioning for those with TBI. Relative t o controls, speed of processing in the TBI group was disproportionately slo wer when information was presented in the auditor relative to the visual, m odality. Conclusions: Speed of information processing is a major impairment in those with TBI when unconfounded by performance accuracy. The modality- specific impairment observed in the TBI group may, in part, be due to a gre ater within-modality interference effect created by the auditory version of the task. By manipulating information at a pace customized for an individu al through compensatory strategies and environmental environmental modifica tions, information-processing performance of TBI participants can be enhanc ed significantly.