Safe driving requires the co-ordination of several ongoing processes including attention, perception, memory, and executive functions and may be affected by verbal distraction. The goal was to quantify how driver safety is affected by increased attention demands created by a controlled auditory-verbal mental processing load. Thirty-eight motorists, 13 of whom had had a closed head injury (CHI), drove on public roads around Iowa City, Iowa in an instrumented vehicle that uses hidden instrumentation to measure driver performance. Administration of the Paced Auditory Serial-Addition Test (PASAT), a verbal serial-addition task lasting approximately 2 minutes, introduced distraction and provided an index of multitasking during driving. Off-road, the CHI group performed significantly worse (p<.05) than the control group at slower PASAT presentation rates. Yet, neither group showed any significant difference between PASAT scores in the laboratory versus while driving, on each of two different types of roadway. Moreover, the CHI group showed no effect of PASAT on driving measures, suggesting no trouble in the ability to divide attention, and apparently at odds with Schiffrin and Schneider's conceptualisation of divided attention deficits. These negative findings may be related to safety-dictated low-traffic conditions under which the divided attention task had to be administered. They may also reflect a relative separation between the auditory-verbal resources commanded by the PASAT and the low-level visuomotor and visuospatial attention processes involved with automobile driving on uneventful roadway segments. For the covering abstract see ITRD E113725 (C 22328 CD-ROM).
Samenvatting