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Driving Simulator Study - Measuring Static Billboard Distraction on Cognitive Functioning

Researcher Lee Hou De

Supervisors Dr Laurence Hartley & Mrs Libby Brook

Date: Completed 2011

Project Number: 2011/098

Description:

Background

Despite driving being such a resource intensive activity, drivers are exposed to an increasingly complex visual environment. It is well established that texting messages, attending to a baby seated at the back seat, using the GPS when driving are distractive in nature. They can cause traffic accidents resulting in serious injuries, or worse, fatalities. These are just some examples of in-vehicle distractions. However, not so much is known about distractions that exist outside of the vehicle, particularly, roadside advertisements.

The aim of this study was to measure cognitive distractions imposed by static billboards on a group of young female drivers.

Methodology

The experiment was designed based on a dual task paradigm. Participants had to drive on a simulated highway whilst performing a secondary subtraction task. The subtraction task varied if both visual and auditory modalities. Roadside advertisements were shown at random interval blocks throughout the experiment. The duration between each subtraction task was varied to simulate different traffic complexity conditions. Subtraction task performance (e.g. percentage of correct responses, percentage of missed responses, and mean reaction time) was used as a cognitive indicator of workload in the presence of advertisements.

It was hypothesized that: 1) subtraction task performance should deteriorate in the presence of advertisements(e.g., decrease in percentage of correct response; increase in percentage of missed responses; and increase in mean reaction time); 2) participants should perform poorer in the visual subtraction task (VST) than the auditory subtraction task (AST) (e.g., decrease in percentage of correct response; increase in percentage of missed responses; and increase in mean reaction time); 3) subtraction task performance should improve (e.g., increase in percentage of correct response; decrease in percentage of missed response) when the inter-stimulus intervals are longer (8-sec; low traffic complexity) as opposed to inter-stimulus intervals that are shorter (2-sec; high traffic complexity).

Results

Generally, when advertisements were shown, participant’s performance in the subtraction task (percentage of correct responses, percentage of missed responses, and mean reaction time) deteriorated, though this result was marginally non-significant. Participants performed worse when the subtraction task was presented visually. Furthermore, when the demand of driving was low (low traffic complexity), subtraction task performance significantly deteriorated.

Conclusion

It appears that billboard advertisements do increase cognitive workload, but only in certain conditions. In particular, participants were cognitively distracted by advertisements when the mental demand of driving was low. It was also found that participants had an approximately 150ms delay when responding to visual stimuli as opposed to audio whilst driving with advertisements shown, further supporting the visual dependence in driving.This study hopes to steer research beyond classifying advertisements as visual distractors (looking away from the road), but as cognitive distractors (not being able to make the quick, safe, and correct decisions).