Objective:: To assess speed of information processing by two serial addition tests (one visual, one auditory) in individuals with moderate-to-severe traumatic brain injuries (TBIs) and in a healthy, normal control group (NC). The tasks were designed to equate and control for accuracy of performance across the TBI and NC groups, thus allowing for quantification of information processing speed.
Design:: Performance across groups and tasks were compared using 2 × 2 repeated measure analyses of variance (ANOVAs). In addition, each individual's processing speed was used to adjust rate of stimulus presentation on a subsequent “rehabilitation” trial to determine further whether 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 speed was slower in TBI subjects, relative to controls and was significantly related to measures of executive functioning for those with TBI. Relative to controls, speed of processing in the TBI group was disproportionately slower when information was presented in the auditory, relative to the visual, modality.
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 greater within-modality interference effect created by the auditory version of the task. By manipulating information at a pace customized for an individual through compensatory strategies and environmental modifications, information-processing performance of TBI participants can be enhanced significantly.
Clinical Neuropsychology Postdoctoral Fellow, Department of Psychology* (Madigan)
Director of Neuroscience Research, Department of Research†¶ (DeLuca)
Research Scientist†‡¶ (Diamond)
Department of Neuropsychology and Cognitive Remediation§, Department of Psychiatry¶ (Tramontano)
Senior Physiatrist†¶ (Averill)
This research was supported by Grant 171 from the Henry H. Kessler Foundation, Inc. The authors would like to thank Chris Pernell for her assistance in data collection. This study was presented in part at the annual meeting of the American Psychological Society, Washington, DC, May 1998.
Address correspondence to John DeLuca, PhD, Neuropsychology and Neuroscience Laboratory, Kessler Medical Rehabilitation Research and Education Corporation, 1199 Pleasant Valley Way, West Orange, NJ 07052, email firstname.lastname@example.org.