Comparison of interocularsuppression for binocular rivalry

and flash suppression

David F. Nichols andHugh R. WilsonCenter for Vision ResearchYork UniversityToronto, ON, Canada

Background

Binocular Rivalry

Background

Binocular Rivalry

Flash Suppression

Suppression spreadsacross space.

Purpose

• Examine similarities and differences betweenbinocular rivalry and flash suppression

• Test with: Experiments and Model

• Hypothesis: same inhibitory mechanisms underlie both

Binocular Rivalry Methodology

Participants reported whenever the center: A) Became Invisible. B) Any portion was visible.

Left Eye Right EyeTime

60 sec

Example Percepts

CenterVisible

CenterInvisible

Flash Suppression Methodology

Participants rate suppression of center:0: Entirely visible, 1: Mostly visible, 2: Mostly invisible, 3: Entirely invisible

Example Perceptsand

Suppression Rating

0. 1.

3.2.

Left Eye Right EyeTime

4 sec

0.5 sec

Experiment 1 MethodologyLeft Eye Right Eye

Opposite Eye Surround

Same Eye Surround

Left Eye Right EyeTime

Adapt

Test

Orthogonal Surrounds

Identical Surrounds

Adapt

Test

Experiment 1 Results

Necessary and sufficient: monocularcenter and surround in contralateral eyeIpsilateral surround: no effect

Flash Suppression

Supp

ress

ion

Rat

ing N=4

BinocularCenter

SameEye

OneEyes

TwoEyes

Monocular Center

OrthogonalSurrounds

IdenticalSurrounds

Opp.Eye

Identical surrounds preventssuppression

Binocular Rivalry

Supp

ress

ion

Tim

e(p

er 6

0 se

cond

tria

l) N=6

Monocular Center

OrthogonalSurrounds

IdenticalSurrounds

OppositeEye

Model Simulations of Common Mechanism

Model consistent with experimental data.

Time

Firin

g R

ate

Time

Firin

g R

ate

Time

Firin

g R

ateIdentical

Surrounds(ωi=0)

OrthogonalSurrounds(ωi=1)

Flash SuppressionBinocular Rivalry

Left Eye Right Eye

SLeft

CLeft

SRight

CRight

ωiSLeft

CLeft

SRight

CRight

Flash On Stim Off

Time

Firin

g R

ate

Flash On Stim Off

Ipsi Eye Contra EyeAnnulusWidth

Experiment 2 Methodology

0.50º

1.30º

For Flash Suppression:9 Annulus Widths:0.05º - 1.30º

For Binocular Rivalry:3 Annulus Widths:0.05º, 0.20º, 1.30º

Experiment 2 Results

Maximum suppression: mid-range annulus width (~0.18 deg)

Flash Suppression Binocular Rivalry

Annulus Width Annulus Width

Supp

ress

ion

Rat

ing

Supp

ress

ion

Tim

e(p

er 6

0 se

cond

tria

l)N=3 N=3

Why the difference?

Maximum suppression:highest annulus width

Center: 100% Center: 50%Center

Diameter

Experiment 3 Methodology

1.0º

1.8º

2.6º

Different Center Diameters:

100% - 50%

Experiment 3 Results

Why the difference?

Maximum suppression: large annulus/center

Maximum suppression:small annulus/center

Flash Suppression Binocular Rivalry

Center Diameter Center Diameter

Supp

ress

ion

Rat

ing

Supp

ress

ion

Tim

e(p

er 6

0 se

cond

tria

l)N=3 N=3

Experiment 2b: Binocular Rivalry

Is dominance of surround in opposite eye correlated with suppression?

Dominance Durations(Opposite Surround)

Suppression Durations (Center Grating)

Dominance of contralateral surround necessary for suppression.Flash Suppression: immediate, Binocular Rivalry: requires interaction

Annulus WidthAnnulus Width

Participant CO Participant DN

Flash Suppression Binocular Rivalry

Annulus Width Annulus Width

Supp

ress

ion

Rat

ing

Supp

ress

ion

Tim

e(p

er 6

0 se

cond

tria

l)

N=3 N=3

2-D Spatial Model

Flash Suppression Binocular Rivalry

Center Diameter Center Diameter

Supp

ress

ion

Rat

ing

Supp

ress

ion

Tim

e(p

er 6

0 se

cond

tria

l)

N=3 N=3

Annulus Width

Participant CO

Dominance Durations(Opposite Surround)

Suppression Durations (Center Grating)

1.0º

2.6º

CenterDiameter

VisualSpace

CorticalSpace

Conclusions1) Differences between Binocular Rivalry and Flash

Suppression:A. Flash Suppression: Get suppression with contralateral surround. Binocular Rivalry: Fusable surrounds prevents suppression.

B. Suppression increased monotonically as a function of annulus width forBinocular Rivalry, but peaked at mid-range width for Flash Suppression.

C. Suppression increased with annulus diameter for Flash Suppression,decreased with annulus diameter for Binocular Rivalry.

2) Modeling: different experimental findings result of sustainedversus transient activation.

Thank you.

Example Stimuli

Model Simulations of Common MechanismLeft Eye Right Eye

SLeft

CLeft

SRight

CRight

SLeft

CLeft

SRight

CRight

!

900*dHLS

dt= "HLS + SLeft + noise

!

20*dSLeft

dt= "SLeft +

100* 30 " .75* SRight " .10*CRight[ ]+

2

10 + HLS( )2

+ 30 " .75* SRight " .10*CRight[ ]+

2

!

20*dCLeft

dt= "CLeft +

100* 30 " .75*CRight " .10* SRight[ ]+

2

10 + HLC( )2

+ 30 " .75*CRight " .10* SRight[ ]+

2

!

900*dHLC

dt= "HLC + CLeft + noise

!

900*dHRS

dt= "HRS + SRight + noise

!

20*dSRight

dt= "SRight +

100* 30 " .75* SLeft " .10*CLeft[ ]+

2

10 + HRS( )2

+ 30 " .75* SLeft " .10*CLeft[ ]+

2

!

20*dCRight

dt= "CRight +

100* 30 " .75*CLeft " .03* SLeft[ ]+

2

10 + HRC( )2

+ 30 " .75*CLeft " .03* SLeft[ ]+

2

!

900*dHRC

dt= "HRC + CRight + noise