#409 (VSS ‘08)
Static and flicker MAE
for global motion
Satoshi Shioiri Kazumichi Matsumiya and Hayato Tamura
Research Institute of Electrical Communication, Tohoku University
INTRODUCTION
VSS ’06: The slow and fast motion detectors isolated by an MAE procedure
High spatial frequency dominance of the static MAE
Low spatial frequency dominance of the flicker MAE
Slow and fast motion detectors
Static test
They perceive MAE in the direction
opposite to the high spatial
frequency drifting grating.
Adaptation
Adaptation
Flicker test
Static test
Flicker test
Observers see motion in the
direction of the low spatial
frequency grating.
They perceive MAE in the direction
opposite to the low spatial
frequency drifting grating.
After the exposure to overlapped sinusoidal gratings with different spatial frequencies moving in the opposite
directions, motion aftereffect of the high spatial frequency grating was seen with a static test (high spatial
frequency superiority) while that of the low spatial frequency was seen with a flicker test. Assuming two types
of motion detectors with different spatiotemporal frequency tunings can explain the results.
Te st
The two types of motion detectors may have different functions.
Slow MD: sensitive to relative motion and selective to orientation.
Fast MD: not sensitive to relative motion nor selective to orientation.
Ada
pt
VSS ’07: The slow motion detector contributes to global motion
The static MAE duration increases with the increase of the degree of global motion.
The flicker MAE duration is approximately constant across the all patch conditions.
Rotation
E
A
M
F
S
h
ig
H
E
A
M
F
S
w
o
L
Expansion/Contraction
Static
18
16
14
E
A
M
F
S
h
ig
H
Flicker
) 12
(s 10
n
8
o
ti
a
r 6
u 4
d
E 2
A
M 0
-2
N=6
-4
-6
1
2
4
8
8-1
E
A
M
F
S
w
o
L
0.53 c/deg
5 Hz
static
10
flicker
8
)
(s
n6
o
ti
a
r4
u
d
E2
A
M
0
2.1 c/deg
5 Hz
N=3
-2
-4
1
2
4
8
Contrast: 30 times of
threshold contrast at 5 Hz
Number of patches
Number of patches
The two types of motion detectors may have different functions.
Slow MD: sensitive to global motion
Fast MD: not sensitive to global motion
[email protected]
www.vision.riec.tohoku.ac.jp
PURPOSE
To investigate the effect of the global motion component in the
adaptation stimulus on motion aftereffect.
EXPERIMENT
Method we measured MAE after the exposure to different degrees of global motion stimuli
σ=2°
Adaptation: alternating two displays
0.53 c/deg
5 Hz
Eight patch condition
Opposite pair condition
Cross condition
Adjacent pair condition
Test: Either static or 4Hz flicker
(same in all the conditions)
On/Off
adaptation
2.1 c/deg
5 Hz
Or
Or
Or
Or
Off/On
adaptation
4°
Global adaptation
Local adaptation: Global motion is not seen during adaptation
Trial Sequence
Overlapped Gabor patch
Contrast: 30 times of
threshold contrast at 5 Hz
1s
Measure the MAE duration
Pressed one of two keys, which
were assigned for each direction
when the MAE disappeared
1s
10, 20, or 40 s
until respond
4°
Effect of adaptation conditions
Expansion/Contraction
*
Local
Local
*
N=4
ns
ns
ns
Global
Local
Flicker MAE
Static Flicker
Static MAE
MAE duration (s)
*
Global
Global
Low SF MAE High SF MAE
Static MAE
MAE duration (s)
Low SF MAE High SF MAE
Rotation
Global
Global
ns
Global
*
Local
Local
ns
N=4
Local
ns
ns
ns
Global
Local
Flicker MAE
Adaptation duration (s)
*
statistical significance
between global and local
conditions (paired t test)
Adaptation duration (s)
1) The MAE duration increased with the increase of adaptation duration in the all the conditions.
2) Longer static MAEs were found with than without global motion components in the adaptation stimulus.
The effect was clearer when the adaptation duration was longer in both the rotation and expansion/contraction conditions.
3) Durations of the flicker MAE were similar irrespective to the adaptation conditions.
Difference between the expansion and
contraction
Effect of on/off order
0
-1
-2
-3
-4
-5
15
Longer MAE was
found when the
MAE direction was
in expansion.
MAE duration (s)
MAE duration (s)
Rotation
5
4
3
2
1
10
5
0
Expansion/Contraction
Static On/Off
Static Off/On
Flicker On/Off
Flicker Off/On
6
4
2
0
-2
-5
-4
-10
-6
CONCLUSIONS
1) The results indicate that global motion signals enhance the static MAE, suggesting that the
slow motion detector contribute to the perception of global motion.
2) Little influence of global motion was found on flicker MAE, suggesting that the fast
motion detector does not contribute to the perception of global motion.
[email protected]
Little effect of
alternation order was
found. The motion
just before the test
was not crucial for
the MAE duration.
Acknowledgements
This study was supported by
MESSC (GASR(B)-18330153)
to SS and by MESSC (GASRYR(B) 18700253) to KM.
www.vision.riec.tohoku.ac.jp