Iranian Journal of Ergonomics

Introduction: Driving is a complex task engaging high level of cognitive and motor processes. Adding to this complexity, engagement in cognitive secondary tasks such as talking with other passengers, speaking on the cell phone or listening to radio may effect driving performance. In addition, age-related cognitive limitations may adversely challenge driving performance. As the number of elderly drivers is rising, it is important to pay more attention to this matter.

Methods: The effects of cognitive secondary tasks on driving performance were explored through two on-road experiments (with and without listening to a recorded dialogue). In this study thirty-two individuals (male, M = 72.6, SD = 5.43) voluntarily took part in the experiments. The mean driving speed, duration of driving in unsafe-zones, numbers of overtaking, and deviation of lateral lane position were recorded, adopting a radar system and video camera. After determination of the normality of data, paired t test and correlation analysis were conducted.

Results: Mean driving speed (P < 0.05), duration of driving in an unsafe zone (P < 0.05), and numbers of overtaking (P < 0.001) showed considerable reduction of participants’ engagement in listening to the recorded dialogue. In contrast, mean deviation of lateral lane position increased.

Conclusions: The findings revealed that driving performance of elderly drivers was effected when listening to a recorded dialogue. However, in order to increase driving safety, they adopted some compensating strategies.

Introduction: Few studies were conducted to determine the effects of lighting on cognitive performance. However, they could not reach a decisive conclusion. This study investigated cognitive performance of university students exposed to different levels of lighting under laboratory conditions.

Methods: In this experimental study, 33 subjects (age range 19-26 years) performed cognitive tests. Participants were exposed to three levels of lighting (200, 500 and 1500lux) in laboratory conditions while performing CPT tests to investigate percentage of attention and reaction time machine that measures reaction time.

Results: The results of this study showed that the maximum percentage of attention (99.75%) belonged to lighting of 1500 (lux) and the minimum percentage of attention was related to 500(lux) (99.36%). statistical analysis showed significant differences in percentage of attention in different levels of lighting (P=0.004). In addition, results of data analysis showed that increase in intensity of  lighting can make a significant change in the average response time (P˂0.001), correct response (P=0.004), commission error (P=0.001) and omission error (P=0.017). With increasing the lighting intensity, reaction time has decreased. The reaction time showed significant differences  at all levels of lighting (P˂0.001)

Conclusion: According to the findings of this study, lighting causes a decrease in reaction time and increase in attention. Thus, the lighting should be taken into account while designing of job and tasks which need attention or reaction time.