VISUAL SPACE ANISOTROPY IN
FULL-CUE AND
REDUCED-CUE CONDITIONS
Oliver Tošković
Faculty of Philosophy, Kosovska Mitrovica;
Laboratory for Experimental Psychology, Belgrade, Serbia
VISUAL SPACE GEOMETRY

Blumenfeld and Hillebrand:

parallel alleys lie inside distance alleys
VISUAL SPACE GEOMETRY

Luneburg – perceived
space is Riemannian
space (with constant
Gaussian curvature)

Points on a Vieth-Müller
circle are being perceived
as equidistant from the
observer

Hyperbolae of Hillebrand
are being perceived as
radial lines of constant
direction
x
y
L
D
VISUAL SPACE GEOMETRY

Luneburg – perceived
space is Riemannian
space (with constant
Gaussian curvature)

Points on a Vieth-Müller
circle are being perceived
as equidistant from the
observer

Hyperbolae of Hillebrand
are being perceived as
radial lines of constant
direction
x
y
L
D
VISUAL SPACE GEOMETRY

Luneburg – perceived
space is Riemannian
space (with constant
Gaussian curvature)

Points on a Vieth-Müller
circle are being perceived
as equidistant from the
observer

Hyperbolae of Hillebrand
are being perceived as
radial lines of constant
direction
x
y
L
D
PHYSICAL vs PERCEIVED SPACE

Herman von Helmoltz:


Difference between physical and perceived horopter
Change in perceived horopter with distance
horopter
L
R
PHYSICAL vs PERCEIVED SPACE

Koenderink, J. Cuijpers, R.
perception of parallelism
observer
distance perception
MOON ILLUSION



Ptolemy – apparent distance
Alhazen – moon illusion as a
psychological phenomenon
Rock and Kaufman
– apparent distance theory
– flattened sky dome
physical dome
perceived dome
Standing
Lying
y=0.69x
y≈ x

Tošković (2004)


x
Indoor
distance perception
Elliptic model of
visual space
(anisotropy)


x
a
b
y=0.73x
y=0.74 x
Phisically shorter
vertical distances =
Outdoor
longer horizontal
Vertical distances are
peceived as beeing
longer
x
c
Standard distance
Estimate
Non-veridicality
x
d
Rock and Kaufman
standing

Tošković (2007)



For near distances,
such as 1m, visual
space is isotropic
For larger distances
(3m and larger) visual
space is anisotropic
For distance estimates,
visual system uses
additional information
from:


lying
eyes
head
body
Vestibular system
Neck muscles
physical
distance
perceived
distance
deviation
perceivedphysical size
TO RESUME:

In a reduced cue-situation:




For perceived distance, visual space is anisotropic
It relies on additional vestibular and kinesthetic
information
Anisotropy – an internal model of visual space
In a full-cue situation:

?
AIM



Does visual space anisotropy exist in full cue
situation, as in reduced cue situation?
Does kinesthetic information influence distance
perception in full cue situation, as in reduced cue
situation?
Does visual system relie on its internal model of
space even when visual information are present?
METHOD

Two experiments were conducted, with participants
lying on their left side of the body




Head moving does not change vestibular information
Uniform distribution of depth cues in all directions
Sample: 37 psychology undergraduates and high
school students
Stimuli:



three luminous objects
rectangular in shape
size: 7* 5 centimeters
EXPERIMENT 1: reduced-cue


Sample: 13 psychology undergraduates
Procedure:

Participants estimated distances






Three standard distances to estimate - 1, 3 i 5 meters
Three directions of estimate




In a dark room – reduced cue situation
Lying on a floor, on left side of the body
With special glasses on their eyes (with horizontal apertures 1mm wide)
With rectangular frame around their head
horizontal (00)
middle – tilted for 450 regarding to horizon
vertical (900)
Task – equalize the distances of three stimuli on a three different
directions
frame
glasses
stimuli
RESULTS

DIRECTION: horizontal – middle



DIRECTION: horizontal – vertical



NO significant effect of direction
NO interaction between direction and distance
Significant effect of direction
Significant interaction between direction and distance
DIRECTION: middle – vertical


Significant effect of direction
Significant interaction between direction and distance
F(2, 24)=12.890, p=.00016
F(2, 24)=8.3619, p=.00176
7
7
6
6
6
5
5
5
4
3
2
average match
7
average match
average match
F(2, 24)=1.7337, p=.19803
4
3
4
3
2
2
1
1
1
0
5m
0 3m
1m
5m
03m
1m
0 degrees
45 degrees
DIRECTION
0 degrees
90 degrees
DIRECTION
45 degrees
90 degrees
DIRECTION
5m
3m
1m

Visual space is being
ELONGATED towards vertical
direction



For the distances larger than 1m
Effect is NOT measurable on 45o
tilt from horizontal direction
In a reduced-cue situation
visual space is anisotropic:

neck muscles information
influence distance perception
EXPERIMENT 2: full-cue


Sample: 24 high school students
Procedure:

Participants estimated distances






Three standard distances to estimate - 1, 3 i 5 meters
Three directions of estimate




On an open field – full cue situation
Lying on a ground, on left side of the body
With special glasses on their eyes (with horizontal apertures 1mm wide)
With rectangular frame around their head
horizontal (00)
middle – tilted for 450 regarding to horizon
vertical (900)
Task – equalize the distances of three stimuli on a three different
directions
frame
glasses
stimuli
RESULTS

DIRECTION: horizontal – middle



DIRECTION: horizontal – vertical



No effect of direction
No interaction between direction and distance
NO effect of direction
No interaction between direction and distance
DIRECTION: middle – vertical


NO effect of direction
No interaction between direction and distance
F(2, 46)=2.2548, p=.11637
F(2, 46)=.00378, p=.99623
6.0
6.0
5.5
5.5
5.5
5.0
5.0
5.0
4.5
4.5
4.5
4.0
3.5
3.0
2.5
2.0
average match
6.0
average match
average match
F(2, 46)=.23235, p=.79359
4.0
3.5
3.0
2.5
2.0
4.0
3.5
3.0
2.5
2.0
1.5
1.5
1.5
1.0
1.0
1.0
0.5
0.5
0.5
0.0
0 degrees
45 degrees
DIRECTION
5m
3m0.0
1m
0 degrees
90 degrees
DIRECTION
5m
0.03m
1m
45 degrees
90 degrees
DIRECTION
5m
3m
1m

Visual space is NOT being
ELONGATED towards vertical
direction


Perceived distance does not
change with viewing direction
In a full-cue situation visual
space is isotropic:

neck muscles information
does NOT influence distance
perception
CONCLUSIONS

In a reduced-cue situation:




In a full-cue situation:




For near distances, such as 1m, visual space is isotropic
For larger distances (3m and larger) head tilt ELONGATES space
towards vertical direction
visual system uses additional kinesthetic information from neck
muscles
For all distances visual space is isotropic
Head tilt does not change visual space towards vertical direction
visual system does NOT use additional kinesthetic information from
neck muscles
Presence of visual information reduces significance of
kinesthetic (non-visual) information for distance perception