Assessment of Cognitive Function
using P3 Components of Eye fixation
Related Potentials
Kengo Asahi 1, Mieko Ohsuga 2,1 Graduate School of Engineering of Industrial Engineering,Osaka Institute of Technology
2 Faculty of Robotics & Design, Osaka Institute of Technology
mieko.ohsuga@oit.ac.jp

Introduction
 The ultimate goal of our work is to provide elderly
drivers with training methods or driver assistant systems
appropriate for their individual levels of cognitiveability.
 The assessment method is necessary to access the threephases of the cognitive process; recognition, judgment,and operation.
 In this study, we propose that the response latency
between stimulus presentation and eye fixation—withspecific focus on the P3 component of eye-fixation
related potentials (EFRP)—can be used to develop one
such method of assessment.
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EFRP: Eye-Fixation Related Potentials
Stim. onset
EOG(ElectroOculogram）

EFRP（Eye Fixation
RelatedPotential）

Eye Fixation （EF）
Eye movement
Perception and comprehension
Updating context
P3

Cognitive
Process

Activation of response
ResponseResponse
EF latency
P3 latency
Reaction time from EFReaction timefrom Stim. onset
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MethodParticipants˗ 33 elderly aged 66 – 81 (28 males and 5 females)˗ 6 young male adults aged 21- 23

The experiments were executed with permission of the president of Osaka
Institute of Technology in accordance with the report of the Ethics Committee
on Life Sciences of Osaka Institute of Technology (approval number 2015-4-1).

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MethodExperimental settings
˗ A simulated driving environment consisted ofthree 42-inch LCDs, a car seat, a steering
wheel, an accelerator pedal and a brake pedal

135°
1.3m

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MethodOdd ball Task
˗ Target : Non-Target = 2 : 8
˗ 200 stimuli for a session
˗ duration 0.5 s, intervals 1.8s
TargetNon-Target

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MethodOdd ball Task
˗ Target : Non-Target = 2 : 8
˗ 200 stimuli for a session
˗ duration 0.5 s, intervals 1.8s
TargetNon-Target

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Method2 levels of response load based on “Simon effect”
Hypothesis:
response loads and reaction times; “cross” ＞ “straight”
cognitive loads and EFRP latencies; “cross” ＝ “straight”
StraightCross

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MethodMeasurement
˗ 19 ch electroencephalogram (EEG) data based on
the international 10-20 systemusing an electrode cap (Electro-cap Co.) anda multi-purpose biological amplifier (Polymate)˗ Vertical and horizontal electrooculography (EOG)
using small Ag-AgCl electrodes andthe same amplifier
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Method Analysis for obtaining EFRP
˗
˗˗
˗
˗
˗

EEG data were analyzed with respect to linked-ear reference data
Eye movement-related artifacts were removed using ICAEye fixation points were determined by the norm of both EOG
waveforms and used as triggers
EEG data between 300 ms before and 1000 ms after the trigger
were extracted and baseline correction was executed
EFRP were obtained by averaging the extracted EEG data fromtrials with correct responses
A low-pass filter with a cut-off frequency of 8 Hz was applied forsmoothing

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Results
Number of correct answers

Aging effectNumber of correct answers**

Straight

Cross

Young

Straight

Cross

Elderly**＜0.01
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ResultsReaction time

Aging effect****Time [s]Simon effectStraight

Cross

Young

Straight

Cross

Elderly**＜0.01
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Results
Eye fixation latencies

Aging effectTime [s]**Straight Cross

Young

Non Straight Cross Non
TargetTargetElderly**＜0.01
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Results
EFRP: grand mean
Elderly

Young
20Pz

151510501050-5-5-10

Straight
Cross
Non-Target

Pz

EFRP [μV]

EFRP [μV]20Straight
Cross
Non-Target

00.5

Time [s]1-1000.5

1Time [s]ACED2017 2017.06.04

ResultsEFRP: scarp distribution
0.42 S

0.44 S

0.45 S

0.48 S

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Results
EFRP latencies

Aging effectTime [s]**Straight

Cross

Young

Straight

Cross

Elderly**＜0.01
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Conclusions
Aging effects were confirmed in˗ eye fixation latencies
˗ P3 latencies of EFRP
˗ reaction times
Large individual differenced were found inthese indicesCognitive process may be assessed divided
into three phases;˗ detection
˗ judgement˗ operation
The assessment method for individual person
should be studied in the future workACED2017 2017.06.04

Acknowledgements

This work was supported by the International
Association of Traffic and Safety Sciences(Research Project No.H2757).

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