Distraction From Multiple in-Vehicle Secondary Tasks

8/2/2019 Distraction From Multiple in-Vehicle Secondary Tasks

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마스터 부제목 스타일 편집

Distraction from multiple in-vehicle secondary tasks: vehicle performance and mental workload implica-tions

Baek SujungChoi DongheeNam Kyung Hyun



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Contents

n Introduction

n Methodn Results

n Discussion

n Conclusion

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Introduction

n Terry C. Lansdown, Nicola Brook-Carter & Tanita Kersloot (2004)

n Ergonomics

n Impact of multiple in-vehicle secondary tasks on driver’s primarytask performance, mental workload, and emotional state.

n The implications of the findings from the experiment and theneed to integrate and manage complex in-vehicle informationsystems are discussed.

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Introduction

n Motivation

l Human Information Processing Modeln Limited Attentional Resource

l Multiple resources and Mental workload (Wickens & Hollands, 2000)

n Demands arise from individual tasks and combinations.

n Perceptual and cognitive (e.g., working memory) tasks use different re-sources from those underlying the selection and execution of action.

n Similar tasks compete for the same modular resources. → Processing Capac-ity ↓ → performance ↓

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Figure. Human Information Processing model (Wickens, 1982) and Multiple resource theory (Wickens,

1984)



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Introduction

n Previous works

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Authors Purpose Findings

Dewing et al., 1995

To Investigate the impact of simultane-ous information conflicts caused by in-teracting with more than one secondarytask on the driving task .

Uncertainty in combination with the variabilityof primary task demands has raised concernsregarding potential disruption of safe drivingbehavior

Zwahlen et al., 1988,Wierwille, 1993

To find the potential impact of secondary

information systems on driving

Interface design

Wilde, 1994 Personality

Summala, 1996 Experience

Handcock & Verwey,1997

To find the factors that produce perfor-mance decrements for drivers interact-ing with in-vehicle information

Mental workload

Matanzo & Rockewell,1967;

Liu, 1996Attentional allocation

Summala et al., 1998 Driving experience


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Introduction

n Driving task demands

l Dual taskn Digit detection (Brown and Poulton 1961)

n Digit repeat tasks (Wierwille et al. 1977, Wierwill and Gutmann 1978)

n Sequence following (Brown 1965)

n Detection of double stimuli (Brown 1965)

n Rearview mirror traffic monitoring (Wagner et al. 1977)

n Slowing complexity hypothesis (Salthouse 1982)

l Dual task may be conceptualized as a complex single task

l Dual task performance decrements are suggested to be due toincreases in overall task complexity

l But, doesn’t hold universally true (Kortling 1994)

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Introduction

n Theoretical dual task performance (Gopher 1990)

l Harder primary task results in a reduction in task performancethan easy primary task

l Introduce secondary task to the easy primary activity impairprimary task performance

l Performance during a hard primary task is significantly de-

crease by the secondary taskn (operators’ central processing capacity has been exceeded, primary perfor-

mance suffers)

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Figure. Theoretical dual task performance



Introduction

n Null hypotheses

l There would be no significant differences in vehicle control,mental workload or emotional state during interacting withmultiple in-vehicle tasks when compared to single tasks ornormal driving

l Unpredictable (unpaced) task interruptions would not be sig-

nificantly different to predictable (paced) task interruptions forvehicle control, mental workload or emotional state

n In this study, participants were presented with simulta-neous visual tasks to address concerns with task conflicts

that are comparable with in-vehicle information system.

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Methods

n Design

l Repeated measures designl Task type : Between participants factor (paced, unpaced,

paced and interruption)

n Participants

l 23 participants (11 males, 12 females)

l Age range 18 – 59 yrs (mean: 40.17 yrs)

l Experienced drivers:n Average annual distance driven 23800km

n Average percentage distance driven on motorway 30.2%

n Average number of days driven 6.4 days/week

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Methods

n Apparatus and materials

l TRL Driving Simulatorn Full size car is surrounded by 3 screens

n Scene is updated at rates between 30 - 60Hz

n Car is mounted on hydraulic rams

l In-vehicle ‘landscape’ displays (100 x 75 mm)

l Paper-based NASA TLX (Hart and Staveland 1988)

n Subjective mental workload assessment

l Paper-based UWIST (Matthews et al. 1990)

n Mood adjective checklist

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Procedure

n Training task

l Familiarizationl Training session lasted between 5 to 10 min.

l Participants were asked to drive on the UK M3 motorway:n 3 lanes with 4 to 8 other vehicles

n Vans or lorries would be within the 200m ahead or behind the driven car.

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After the training, pre-test levels of subjective mental workload and emotionalstate were obtained.

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Figure. 3-lane M3 motorway



Results

n Experimental trial

l Paced taskn While driving , numbers were presented on the left screen with regular in-

terval (approximately 30sec.).

n Press right key in response to the even number, and press left key to theodd number.

l Unpaced task: the same with paced task except that the numbers were pre-

sented at an irregular rate. (15sec. to 3 min.)l Paced and interruption task: in addition to the paced task, letter stimuli were

presented on the right screen at an irregular rate (letter stimuli have higher pri-ority to be processed).

n Participants were instructed to press up key to the vowels, and to pressdown key to the consonants

l Control task: no secondary tasks.

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Results

n Mental workload (NASA-TLX)

l Overall score: Paced & Interrupted>> Paced, Unpaced>> Control

l Sub-components: significant differences were found in mental demand, physicaldemand, temporal demand, effort, and frustration

n Mental & temporal demand: Paced & Interrupted, Paced, and Unpaced >>Control

n Physical demand, Effort, & Frustration: Paced & Interrupted >> Control

l Performance: no significant differences were found between 4 different tasktypes

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Figure. Subjective mental workload by task type



Results

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n UWIST mood checklist

l No significant differences were found between 4 differenttasks

n Headway

l Def.: The distance between the driven car and the car ahead.

l Data was collected by the driving simulator automaticallywhen a vehicle is closer than 200m ahead.

l A significant difference was found in headway between the dif-ferent task types (F=18.12, df =3, p<0.001)

l Greatest headway: Control task (mean: 9.67m) / least head-

way: Unpaced (mean: 2.4m)n Post hoc: Control , Paced & Interrupted (mean: 7.85m) >> Paced (mean:

6.12m), Unpaced (mean: 2.4m)

n No significant differences were observed between any of the three tasktypes involving a secondary task.



Results

n Brake pressure

l Standard deviation of brake pressure was significantly differ-ent between task types (P < 0.01)

l Post hoc: Unpaced >> the other three tasks

l No significant differences were found between the Paced, Paced and Interruptedand the Control types.

l No gender effects were found.

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Figure. Summary of brake pressure by task type



Results

n Mean speedl Significant difference between the tasks was observed (p < 0.001)

l Post hoc: Control (32.0mph) >> Unpaced (30.2mph), Paced (30.0mph) and Paced and In-terrupted (29.4mph)

l A significant differences was observed between the mean speeds of males and females.(p < 0.05)

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Figure. Speed and Gender by condition



Results

n Lane position and movement in lane

l No significant differences were observed

n Secondary task reaction time

l A significant difference was observed between the mean reac-tion times for correct responses to the tasks (p < 0.001)

l Incorrect mean reaction times were found to be significantlydifferent between the 4 tasks. (p = 0.001)

1818Figure. Mean correct and incorrect secondary task reaction times by secondary tasks



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Results

n Secondary task performance

l The percentage of correct responses to the secondary taskswas significantly lower in the interruption task. (p < 0.001)

l The distraction of the interruption task did not degrade per-formance of the paced task.

1919Figure. Mean correct and incorrect secondary task reaction times by secondary tasks




Discussion

n Mental workload

l Overall mental workload was significantly lower during normaldriving in comparison to the dual task.

n Response time

l High priority task was quicker than other secondary tasks.

n Accuracy

l High priority task was less accurate than the comparable othertasks.

n Mean speed

l During normal driving was faster than other conditions.

l Because vehicle speed is reduced to offset the increasingworkload.

l Visual occlusion and vehicle speed were used interchangeably2020




Discussion

n Headways

l Reduced when interacting with a single secondary taskl It interrupts maintaining a comfortable headway compared

with normal driving.

l Spatial uncertainty during concurrent visual tasks has beenshown to produce greater task interference than concurrent

verbal tasks (Liu, 1996)l Drivers might adopt a selective attentional resource during

single secondary task, but multiple simultaneous secondarytask might require one of divided attentional allocation.

l Between paced and unpaced conditions, the drivers’ ability to

control the vehicle was disrupted but the task does not per-ceived as complex task needed cautious manner.

n Brake pressure

l Increased during unpaced task with interruption of the drivers’

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Conclusion

n The influence of multiple non-driving tasks on vehicle and sec-

ondary task performancel Greater mental workload

l Lower vehicle speeds

l Reducing headways

l Greater brake pressure

n The information overload from cellular telephone, navigation andmobile office applications makes driver mediate the distractionfrom in-vehicle information system as well as several devices.

l Integration and management of driver information is advocat-

ed

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Limitations & Future work

n Limitations

l The result of subjective emotion evaluation may affected bythe personality (stress vulnerable or patient) rather than thetask difficulty.

n The subjects’ personality should be assessed before the experiment.

l Simple primary task : driving task was performed in a straight course.

n Future work

l The impact of distraction from other sensory stimuli, such astactile or auditory information.

l Which combination of the stimuli is the most efficient and theleast demanding?

n visual and auditory information, or visual and tactile information, or auditoryand tactile information.

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NASA-TLX

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UWIST

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Distraction From Multiple in-Vehicle Secondary Tasks