Driver ’s Attention during Monotonous Driving

Copyright © 2007 LICS | DCSE | FAS | UWB

Driver’s Attention during Monotonous Driving

Roman Mouček, Jan Řeřicha

University of West Bohemia

Pilsen, Czech Republic


Introduction

• Why

– Attention of drivers – road safety

– Decline of attention is natural

• What:

– Investigation of driver’s attention during monotonous driving

• How:

- Electric activity of human brain

- Technique of event related potentials (ERP)

- ERP experiment based on auditory stimulation

• Results


Attention of drivers

• Long rides• Monotonous driving – motorways• Not focused on prolongation of driver’s reactions• EEG (electrophysiology) vs. ERP (event related

potential)• Auditory stimulation during monotonous drive –

changes in the peak latency of the P3 component


Hypothesis

• Peal latency of the P3 component increases in time as the driver is more tired from monotonous drive


ERP and P3 Component

• Advantages compared to behavior techniques– Which stages of processing are influenced by experimental

manipulation– Online measure of the processing of stimuli

• P3 component – depends entirely on the task performed by the subject – Sensitive to variety of factors– Related to process called “context updating”– sensitive to the probability of the target stimulus.


P3 amplitude

• P3 amplitude – increases when the probability of the target stimulus class

decreases – becomes larger when it is preceded by a greater number of

non-target stimuli – is larger when the subject pays more attention to a task– is smaller if the subject does not know whether a given

stimulus is / is not a target


P3 latency

• associated with stimulus categorization• If stimulus categorization is postponed, P3 latency is

increased • While P3 latency depends on the time required to

stimulus categorization it does not depend on consequent processes (e.g. response selection)

• can be used to determine if a performed experiment influences the processes of stimulus categorization or processes related to a response


Experiment - Objectives

• To construct a highly monotonous track where a substantial decrease of attention is supposed.

• To design and implement a common auditory ERP experiment.

• To perform the ERP experiment on the group of tested subjects.

• To divide the drive into time intervals of the same length and compare the latency of the averaged P3 components in these time intervals.

• To evaluate results to confirm/reject the hypothesis.


Laboratory


Laboratory


Track


Laboratory - metadata

• Hardware equipment • Software tools• Recording System• Tested subjects • Course of experiments• Environment• Data and metadata storage


Recording system

• 10-20 system• The cap reference electrode used first, then reference

electrode was placed above the nose


Tested subjects

• A group of 14 men• university students, aged 21-23, • All of them were right-handed, no visual or auditory

defects. • All of them had a driving license


Course of experiment

• Preparation phase– standard biorhythms– not to drink any stimulating substances and alcoholic

beverages – to come not exhausted. – familiarized with the basic behavioral rules during an

EEG/ERP experiment– ….

• Experiment - 40 minutes• Closing phase - several questions related to subjects’

feeling of tiredness


Data processing

• Data import• Data filtering• Rejection of corrupted data• Data selection• Channels selection• Extraction of epochs• Baseline correction• Data averaging


Results

Interval (min) [0-8] [16-24] [32-40] average

Electrode Fz Cz Pz Fz Cz Pz Fz Cz Pz Fz Cz Pz

subject 7 415 415 469 413 424 432 473 471 472 422 428 449

subject 8 314 322 332 316 308 334 315 315 323 312 316 328

subject 9 358 354 360 382 380 376 378 368 362 375 368 367

average 385 371 353 394 391 378 398 375 345 395 382 358


Results – cap reference, Cz electrode


Results – nose reference, Cz electrode


Conclusion

• P3 component was found• prolongation of peak latency over time could not be

clearly observed• long target stimulus stretched the length of the

component - stretched components are worse analyzable - absolute coordinates are distorted.

• not many of target stimuli because of frequent removal of the artifacts

• this kind of attention decline did not affect peak latency of the P3 component.


Thank you for your attention

Documents

Driver ’s Attention during Monotonous Driving