Effects of cognitive tasks on car drivers’ behaviors and physiological responses
Doktorsavhandling, 2022

The effects of drivers’ engagement in cognitive tasks (i.e., non-visual, cognitively loading activities unrelated to the task of driving) are debated and unclear. Numerous experiments show impaired driver behaviors, yet naturalistic studies typically do not find an increased crash risk. In the future, autonomous driving (AD) is expected to improve traffic safety while allowing safe engagement in cognitive (and other) tasks. Having the opportunity to perform non-driving related tasks while traveling may then motivate drivers to use AD, provided they can actually engage in the tasks. Unfortunately, research on drivers’ engagement in cognitive tasks suffers severe methodological limitations since reliable and unintrusive measures of cognitive load are lacking.

The aim of this thesis is therefore to advance the understanding of task-induced cognitive load in the context of traffic safety. This aim is split into two objectives: A) to better understand how drivers’ involvement in cognitive tasks can affect safety-relevant driver behaviors and decisions and B) to provide methodological guidance about assessing cognitive load in drivers using physiological measures.

To accomplish Objective A, effects of cognitive tasks on driver behaviors were studied during routine driving and in a safety-critical event in a driving simulator. Also, drivers’ ability to engage in a non-driving related task while using AD in real traffic was explored. In line with the cognitive control hypothesis (Engström et al., 2017), it was found that cognitive tasks negatively affected driver behaviors in situations where cognitive control was needed, for example in intersections—but not in a lead vehicle braking scenario where responses were triggered automatically by visual looming. It was also found that although the number of off-path glances decreased during cognitive load, the timing of the remaining glances was unaffected. Clearly, cognitive load has different effects on different mechanisms. When using AD, drivers were indeed capable of engaging in a non-driving related task—suggesting that AD will be able to fulfill drivers’ desire to perform such tasks while traveling, which may motivate AD usage and thus improve traffic safety (given that AD is truly safer than manual driving). Finally, a simulator study addressing Objective B showed that the measurability of cognitive load was greatly improved by recognizing that multiple coexisting mental responses give rise to different physiological responses. This approach can provide less context-dependent measurements and allows for a better, more detailed understanding of the effects of cognitive tasks.

These findings can help improve traffic safety—both by being used in system development, and as part of the systems themselves.

cognitive load

traffic safety

autonomous drive

inattention

distraction

physiological measures

driver behavior

psychophysiology

Room Delta, house Svea, Forskningsgången 4
Opponent: Prof. Dick de Waard, Department of Clinical & Developmental Neuropsychology, University of Groningen, the Netherlands

Författare

Emma Nilsson

Chalmers, Mekanik och maritima vetenskaper, Fordonssäkerhet

Effects of cognitive load on response time in an unexpected lead vehicle braking scenario and the detection response task (DRT)

Transportation Research Part F: Traffic Psychology and Behaviour,;Vol. 59(2018)p. 463-474

Artikel i vetenskaplig tidskrift

Drivers' Ability to Engage in a Non-Driving Related Task While in Automated Driving Mode in Real Traffic

IEEE Access,;Vol. 8(2020)p. 221654-221668

Artikel i vetenskaplig tidskrift

Let Complexity Bring Clarity: A Multidimensional Assessment of Cognitive Load Using Physiological Measures

Frontiers in Neuroergonomics,;Vol. 3(2022)

Artikel i vetenskaplig tidskrift

The aim of this thesis is to improve our understanding of how car drivers are affected by activities which take their mind, but not their eyes, off the road, such as talking on the phone and using voice control. Many studies show impaired driving abilities when drivers perform such cognitive tasks, yet other studies show that the risk of crashes do not increase. To better understand these seemingly conflicting findings, this PhD work explored effects of cognitive tasks in different traffic scenarios. It was found that reflexive behaviors, such as braking to avoid a collision, were unaffected by cognitive tasks, but more deliberate behaviors, such as looking around for potential threats, were impaired. This finding is important for understanding when cognitive tasks may, and may not, pose a safety problem. In the future, autonomous driving (AD) is expected to allow safe engagement in cognitive (and other) tasks. Being able to do other things while traveling may then be a key reason for drivers to use AD, provided they can really engage in that other activity, such as work. This ability was therefore studied, and it was found that this was indeed the case. To further improve our understanding of the effects of cognitive tasks, we need to be able to measure the mental responses to these tasks (without disturbing the driver). Therefore, this thesis work also shows how physiological measures (e.g., heart rate and pupil diameter) can be used to assess mental responses more accurately, and thus improve traffic safety research and product development in the automotive industry.

Styrkeområden

Transport

Ämneskategorier

Annan teknik

ISBN

978-91-7905-710-7

Doktorsavhandlingar vid Chalmers tekniska högskola. Ny serie: 5176

Utgivare

Chalmers

Room Delta, house Svea, Forskningsgången 4

Online

Opponent: Prof. Dick de Waard, Department of Clinical & Developmental Neuropsychology, University of Groningen, the Netherlands

Mer information

Senast uppdaterat

2022-09-02