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Mid-America Transportation Center

Distracted Driving due to Visual Working Memory Load

Final Report
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  • Principal Investigator: Jonathan Mordkoff (319) 384-3387)
  • Project Status
  • Start Date: 7/1/2013
  • End Date: 12/31/2014
  • About this Project
    Brief Project Description & Background
    Given the clear and known dangers of distracted driving, including the use of a cell-phone while driving, and the failure of both laws and public education to reduce these distractions, the present project was designed to help mitigate these dangers by determining the specific manner in which driving distractions interfere with performance. The general approach and specific hypothesis are based on current theory from cognitive psychology, most notably research on human visual information processing. The working hypothesis to be tested concerns a limitation in visual short-term memory (which can be thought of as the visual storage mechanism that is able to maintain highly accurate “pictures” in the mind for very brief periods of time). Because visual short-term memory is highly limited, distractions can cause large deficits by diverting capacity to visual events unrelated to driving.
    Research Objective
    The goal of this research is to test the hypothesis that driving distractions, including the use of a cell-phone while driving, cause increases in accidents because these distractions use up "space" within visual short-term memory, leaving less room for all of the visual events that are relevant to driving. Because people can use attention to determine which visual events are stored in visual short-term memory, and they use attention to make sure that obviously relevant events are being processed (such as the location of the car in front of them), they are unaware of how driving distractions are causing them to not see other events (such as a car that might pull out of a driveway) until its too late.
    Potential Benefits
    The present work aims to enhance driving safety by uncovering the specific manner in which distractions, including the use of a cell-phone, cause an increase in accidents. This information could then be used to better explain to the general public why distracted driving is so dangerous, including why their own use of a cell-phone is much more dangerous than they might currently believe. It could also be used to devise new human factors solutions to mitigate the increased risk of cell-phone use and other distractions in those situations where efforts to discourage this behavior fail.
    Distracted driving is responsible for many deaths and injuries, and a significant portion are due to the use of a cell-phone. Even people who know of the risks continue to use cell-phones, often saying “it’s no worse than talking to a passenger” (which is not true). In order to enhance safety through means beyond public education, a better understanding of the specific manner in which distractions interfere with the cognitive processing required for driving is needed. Focusing on the limitations of visual short-term memory (VSTM), the present work will examine the hypothesis that concurrent distractions, including the use of a cell-phone, interfere with safe driving by reducing the amount of VSTM that is available for those processes needed for driving. This hypothesis will be tested by manipulating the amount of VSTM that is occupied by a secondary task while participants drive in a simulator. It is predicted that, starting at very low levels of VSTM load, responses to unexpected events will be impeded. As concurrent load is further increased, approaching the limits of VSTM capacity, it is predicted that measures of overall driving performance, such as following distance, will also be affected. These findings would provide valuable evidence concerning the causes of distracted-drivings effects, and would help to explain why many people appear to believe that using a cell-phone is not as dangerous as it actually is.  These findings would also provide preliminary evidence in support of a new model of distracted driving, allowing larger proposals to be submitted to other agencies, while enabling a new collaboration between the National Advanced Driving Simulator, the College of Engineering, the Department of Psychology, and the College of Liberal Arts and Sciences at the University of Iowa. It will expose psychology students to the application of theory and method to problems in traffic safety.
    Total Project Cost
    $ 46,778