A Linear Visual-Vestibular Physiological Model A Linear Visual-Vestibular Physiological Model for the Prediction of Motion Sickness for the Prediction of Motion Sickness Incidence: Revised for Motion Detected by Incidence: Revised for Motion Detected by Peripheral VisionPeripheral Vision

ByBy

Lt P. Matsagas, M.Sc., Hellenic NavyLt P. Matsagas, M.Sc., Hellenic Navypmatsang@nps.edupmatsang@nps.edu

M.E. McCauley, Ph.D., Naval Postgraduate SchoolM.E. McCauley, Ph.D., Naval Postgraduate Schoolmemccaul@nps.edumemccaul@nps.edu

HCI International 2005

Motion SicknessMotion Sickness

Motion sickness is a general term that Motion sickness is a general term that describes the discomfort and associated describes the discomfort and associated emesis (vomiting) induced by real or emesis (vomiting) induced by real or apparent motion. apparent motion.

Motion sickness effects are evident in Motion sickness effects are evident in numerous provocative motion environments, numerous provocative motion environments, such as ships, aircraft, automobiles, virtual such as ships, aircraft, automobiles, virtual environments and large computer screens. environments and large computer screens.

Cause of motion Cause of motion sicknesssickness

Neural mismatch theoryNeural mismatch theory

Current sensory input

Neural store

Vestibular systemVision

ProprioceptionError signal

Effects on Effects on performanceperformance The consequences on human performance and The consequences on human performance and

operational efficiency are:operational efficiency are:– Ataxia (Ataxia (lack of muscular coordinationlack of muscular coordination))– Decreased spontaneityDecreased spontaneity– CarelessnessCarelessness– IncoordinationIncoordination– Reductions in subject motivationReductions in subject motivation– Mood changesMood changes– Sleepiness, drowsiness (through sopite syndrome)Sleepiness, drowsiness (through sopite syndrome)– Negative acceptance of the technological system involvedNegative acceptance of the technological system involved

Motion Sickness Motion Sickness Incidence (MSI)Incidence (MSI) A historically common index of motion A historically common index of motion

sickness severity is the Motion sickness severity is the Motion Sickness Incidence (MSI), which is the Sickness Incidence (MSI), which is the percentage of people who vomit when percentage of people who vomit when exposed to a nauseogenic exposed to a nauseogenic environment. environment.

HFR model (1974)HFR model (1974)

Model CharacteristicsVertical AccelerationOnly true motionMSI: % of people who vomitTwo-hour nauseogenic period

Nauseogenic frequency range0.05 – 0.6 [Hz]

Central nauseogenic frequency0.167 [Hz]

Proposed modelProposed model

Conceptually based on existing theoriesConceptually based on existing theories Combined with observer theory conceptsCombined with observer theory concepts MSI estimation based on:MSI estimation based on:

– Gravity estimation errorGravity estimation error– Residual optical flowResidual optical flow

Model input parametersModel input parameters– True motion characteristics (Vertical acceleration True motion characteristics (Vertical acceleration

frequency and amplitude) detected by the frequency and amplitude) detected by the vestibular systemvestibular system

– Apparent motion characteristics (Vertical Apparent motion characteristics (Vertical acceleration frequency and amplitude) detected acceleration frequency and amplitude) detected by peripheral visionby peripheral vision

Model OverviewModel Overview

Peripheral Vision SystemVisual World Motion

VestibularSystem

Head externally induced motion

Error Estimation Subsystem

VORInterface

Visual systemVisual target tracking

Motion parametersExtraction

AdaptationSubsystem

Gravity ErrorResidual Optical Flow

VOR

ROF

ADAPT

Dg

,

Model in detailModel in detail

Predicted MSIPredicted MSITrue Motion SettingsTrue Motion Settings

Proposed Model

CharacteristicsVertical AccelerationOnly true motionMSI: % of people who vomitTwo-hour nauseogenic period

Nauseogenic frequency range0.05 – 0.6 [Hz]

Central nauseogenic frequency0.17 [Hz]

Model ValidationModel ValidationTrue Motion SettingsTrue Motion Settings

Proposed model

HFR modelMSI Comparison between Proposed and HFR models

MSI ComparisonMSI ComparisonDoes Peripheral Vision make a difference?Does Peripheral Vision make a difference?

Predicted MSI without Peripheral Vision

Predicted MSI with Peripheral Vision

MSI Comparison between Proposed (no Peripheral Vision) and HFR models

MSI Comparison between Proposed (with Peripheral Vision) and HFR models

Predicted MSIPredicted MSIApparent Motion SettingsApparent Motion Settings

Proposed Model

CharacteristicsVertical AccelerationOnly Apparent MotionMSI: % of people who vomitTwo-hour nauseogenic period

Nauseogenic frequency range0.05 – 0.6 [Hz]

Central nauseogenic frequency0.157 [Hz]

Model significanceModel significance

ParametricParametric Easily extended to various Easily extended to various

combinations of sensory cuescombinations of sensory cues Validated but not “tuned”Validated but not “tuned” PrecisePrecise EtiologicEtiologic Linear and time invariantLinear and time invariant

Why is the model Why is the model useful?useful? Current stateCurrent state

– True and apparent motion detectionTrue and apparent motion detection– Seated subject Seated subject – No voluntary motionsNo voluntary motions

Future stateFuture state– ProprioceptionProprioception– Refinement of Neural Store modelRefinement of Neural Store model– Parametric input of other human physiology Parametric input of other human physiology

parametersparameters

Future ResearchFuture Research

Include motion in 6 degrees of Include motion in 6 degrees of freedomfreedom

Implementation of “all” physiological Implementation of “all” physiological systemssystems

Central Nervous System (CNS) non-Central Nervous System (CNS) non-linear characteristics linear characteristics

Questions?Questions?

Adaptation Adaptation mechanism detailmechanism detail

++

ExponentialIncrease

ExponentialDecrease

+

+

Perceived Linear Acceleration

Perceived Gravity Adaptation

signal

Neural Store

Σ

Future ResearchFuture Research

Current StateCurrent State Future StateFuture State

InputsInputs True motionTrue motionVisually detected motionVisually detected motion

True motionTrue motion Visually detected motionVisually detected motion

Human systems Human systems involvedinvolved

VestibularVestibular Central VisionCentral VisionPeripheral VisionPeripheral Vision

Vestibular Vestibular Central VisionCentral Vision Peripheral VisionPeripheral Vision ProprioceptionProprioception

Neural StoreNeural Store One average motionOne average motion Multiple motion Multiple motion characteristicscharacteristics

Cue errors Cue errors contributing to contributing to MSIMSI

Gravity vector Gravity vector estimationestimation Retinal SlipRetinal Slip

Gravity vector estimationGravity vector estimation Retinal SlipRetinal Slip Difference between true Difference between true motion and vectionmotion and vection

Current effortsCurrent efforts

Modeling ofModeling of

InputsInputs True motionTrue motion Visually detected motionVisually detected motion

Human systems Human systems involvedinvolved

Vestibular Vestibular Central VisionCentral Vision Peripheral VisionPeripheral Vision ProprioceptionProprioception

Neural StoreNeural Store Multiple motion characteristicsMultiple motion characteristics

Cue errors Cue errors contributing to MSIcontributing to MSI

Gravity vector estimationGravity vector estimation Retinal SlipRetinal Slip Difference between true motion and Difference between true motion and vectionvection