Physiological and behavioral evaluation of mental load in shared attention tasks

Area of Science:

• Cognitive Psychology
• Human Factors Engineering
• Traffic Safety Research

Background:

• French law prohibits hand-held phone use while driving to mitigate motor interference.
• The cognitive impact of hands-free phone systems, despite being permitted, requires further investigation.
• Understanding driver distraction is crucial for enhancing road safety.

Purpose of the Study:

• To evaluate the cognitive interference of hands-free phone conversations compared to other in-car communication tasks.
• To assess the impact of communication tasks on driver's reaction time (RT) and physiological arousal.
• To determine the specific demands imposed by hands-free calling on driver attention.

Main Methods:

• Drivers performed a reaction time task (releasing accelerator pedal to visual stimuli) on a closed circuit.
• Three communication conditions were tested: listening to the radio, conversing with a passenger, and hands-free phone calls.
• Physiological measures, including skin resistance level (SRL) and instantaneous heart rate (IHR), were recorded to assess arousal.

Main Results:

• Hands-free phone conversations resulted in the longest reaction times (RT) compared to other tasks.
• Skin resistance level (SRL) indicated increased arousal during dual-task conditions (driving + communication) versus driving alone.
• Instantaneous heart rate (IHR) revealed higher arousal during phone calls than during radio listening, suggesting greater cognitive load.

Conclusions:

• Hands-free phone use imposes a significant cognitive load, leading to delayed reactions to driving stimuli.
• While all communication tasks increase driver arousal, hands-free calling presents the most substantial risk.
• These findings underscore the need for stricter regulations on in-car communication to improve road safety.