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
