Proprioceptive roll and pitch interact in contributing to visual tiltinduced effects.

1
Proprioceptive roll and pitch interact in
contributing to visual tilt-induced effects.
Jennifer E. Corbett James T. Enns The
University of British Columbia
2
Visual and proprioceptive information calibrate
our sense of upright.

3
Visual and proprioceptive information calibrate
our sense of upright.

• We rely on
• The tilt of the surrounding visual
  environment(visual
• orientation cues)

4
Visual and proprioceptive information calibrate
our sense of upright.

• We rely on
• The tilt of the surrounding visual
  environment(visual
• orientation cues)

5
Visual and proprioceptive information calibrate
our sense of upright.

• We rely on
• The tilt of the surrounding visual
  environment(visual
• orientation cues)
• Our sense of the bodys position in space
  (proprioception)

6
Visual and proprioceptive information calibrate
our sense of upright.

• We rely on
• The tilt of the surrounding visual
  environment(visual
• orientation cues)
• Our sense of the bodys position in space
  (proprioception)

7
Visual and proprioceptive information calibrate
our sense of upright.

• We rely on
• The tilt of the surrounding visual
  environment(visual
• orientation cues)
• Our sense of the bodys position in space
  (proprioception)

To determine our
perceptions of upright.
8
Mystery Spots and funhouses are everyday
illustrations of how our perception of
orientation may arise from an interaction between
visual information and our proprioceptive sense.

9
Mystery Spots and funhouses are everyday
illustrations of how our perception of
orientation may arise from an interaction between
visual information and our proprioceptive sense.

The visual tilt of the cabin
10
Mystery Spots and funhouses are everyday
illustrations of how our perception of
orientation may arise from an interaction between
visual information and our proprioceptive sense.

The visual tilt of the cabin and the observers
tilt inside the cabin
11
Mystery Spots and funhouses are everyday
illustrations of how our perception of
orientation may arise from an interaction between
visual information and our proprioceptive sense.

The visual tilt of the cabin and the observers
tilt inside the cabin affect
perceptions of upright.
12
In the present study

13
In the present study

We examined how the roll (clockwise or
counterclockwise rotation along the image plane)
Roll
14
In the present study

We examined how the roll (clockwise or
counterclockwise rotation along the image plane)
Roll
15
In the present study

We examined how the roll (clockwise or
counterclockwise rotation along the image plane)
Roll
16
In the present study

We examined how the roll (clockwise or
counterclockwise rotation along the image plane)
and pitch (rotation up or down in the frontal
plane) of the observer
Pitch
17
In the present study

We examined how the roll (clockwise or
counterclockwise rotation along the image plane)
and pitch (rotation up or down in the frontal
plane) of the observer
Pitch
18
In the present study

We examined how the roll (clockwise or
counterclockwise rotation along the image plane)
and pitch (rotation up or down in the frontal
plane) of the observer
Pitch
19
In the present study

We examined how the roll (clockwise or
counterclockwise rotation along the image plane)
and pitch (rotation up or down in the frontal
plane) of the observer interact with tilted
visual cues
20
In the present study

We examined how the roll (clockwise or
counterclockwise rotation along the image plane)
and pitch (rotation up or down in the frontal
plane) of the observer interact with tilted
visual cues to produce observers perceptions of
orientation.
Pitch
Roll
21
Introduction

22
Introduction

• (Asch Witkin, 1948)

23
Introduction

• (Asch Witkin, 1948) - If true vertical (with
  respect to gravity)

True vertical
24
Introduction

• (Asch Witkin, 1948) - If true vertical (with
  respect to gravity) and the
• visual tilt of the environment are
  different,

Visual tilt
True vertical
25
Introduction

• (Asch Witkin, 1948) - If true vertical (with
  respect to gravity) and the
• visual tilt of the environment are
  different, visual tilt will influence observers
• perceived vertical The tilt induced effect.

Perceived vertical
Visual tilt
True vertical
26
Introduction

• (Asch Witkin, 1948) - If true vertical (with
  respect to gravity) and the
• visual tilt of the environment are
  different, visual tilt will influence observers
• perceived vertical The tilt induced effect.

• (Nelson Prinzmetal, 2003) - Pitch and roll
  of the visual environment
• contribute independently to visual
  tilt-induced effects.

27
Introduction

• (Asch Witkin, 1948) - If true vertical (with
  respect to gravity) and the
• visual tilt of the environment are
  different, visual tilt will influence observers
• perceived vertical The tilt induced effect.

• (Nelson Prinzmetal, 2003) - Pitch and roll
  of the visual environment
• contribute independently to visual
  tilt-induced effects.

Manipulating one dimension does not affect the
influence of the other dimension
28
Introduction

• (Asch Witkin, 1948) - If true vertical (with
  respect to gravity) and the
• visual tilt of the environment are
  different, visual tilt will influence observers
• perceived vertical The tilt induced effect.

• (Nelson Prinzmetal, 2003) - Pitch and roll
  of the visual environment
• contribute independently to visual
  tilt-induced effects.

• Manipulating one dimension does not affect the
  influence of the other dimension

Q1. Do pitch and roll of the observer
independently/interactively influence
visual-tilt induced effects?
29
Introduction

• (Asch Witkin, 1948) - If true vertical (with
  respect to gravity) and the
• visual tilt of the environment are
  different, visual tilt will influence observers
• perceived vertical The tilt induced effect.

• (Nelson Prinzmetal, 2003) - Pitch and roll
  of the visual environment
• contribute independently to visual
  tilt-induced effects.

• (Witkin Asch, 1948) - Tilt-induced effects
  are increased when observers are
• also tilted.

30
Introduction

• (Asch Witkin, 1948) - If true vertical (with
  respect to gravity) and the
• visual tilt of the environment are
  different, visual tilt will influence observers
• perceived vertical The tilt induced effect.

• (Nelson Prinzmetal, 2003) - Pitch and roll
  of the visual environment
• contribute independently to visual
  tilt-induced effects.

• (Witkin Asch, 1948) - Tilt-induced effects
  are increased when observers are
• also tilted.

Observers tilted congruently
31
Introduction

• (Asch Witkin, 1948) - If true vertical (with
  respect to gravity) and the
• visual tilt of the environment are
  different, visual tilt will influence observers
• perceived vertical The tilt induced effect.

• (Nelson Prinzmetal, 2003) - Pitch and roll
  of the visual environment
• contribute independently to visual
  tilt-induced effects.

• (Witkin Asch, 1948) - Tilt-induced effects
  are increased when observers are
• also tilted.

Observers tilted congruently experience larger
tilt-induced effects
gt
32
Introduction

• (Asch Witkin, 1948) - If true vertical (with
  respect to gravity) and the
• visual tilt of the environment are
  different, visual tilt will influence observers
• perceived vertical The tilt induced effect.

• (Nelson Prinzmetal, 2003) - Pitch and roll
  of the visual environment
• contribute independently to visual
  tilt-induced effects.

• (Witkin Asch, 1948) - Tilt-induced effects
  are increased when observers are
• also tilted.

Observers tilted congruently experience larger
tilt-induced effects than incongruently tilted
observers.
gt
33
Introduction

• (Asch Witkin, 1948) - If true vertical (with
  respect to gravity) and the
• visual tilt of the environment are
  different, visual tilt will influence observers
• perceived vertical The tilt induced effect.

• (Nelson Prinzmetal, 2003) - Pitch and roll
  of the visual environment
• contribute independently to visual
  tilt-induced effects.

• (Witkin Asch, 1948) - Tilt-induced effects
  are increased when observers are
• also tilted.

Observers tilted congruently experience larger
tilt-induced effects than incongruently tilted
observers.
gt
(0.8o)
34
Introduction

• (Asch Witkin, 1948) - If true vertical (with
  respect to gravity) and the
• visual tilt of the environment are
  different, visual tilt will influence observers
• perceived vertical The tilt induced effect.

• (Nelson Prinzmetal, 2003) - Pitch and roll
  of the visual environment
• contribute independently to visual
  tilt-induced effects.

• (Witkin Asch, 1948) - Tilt-induced effects
  are increased when observers are
• also tilted.

Q2. Are visual tilt-induced effects really
greater when the observer is tilted
incongruently vs. congruently with the visual
environment? (0.8o is pretty weak)
35
Introduction

• (Asch Witkin, 1948) - If true vertical (with
  respect to gravity) and the
• visual tilt of the environment are
  different, visual tilt will influence observers
• perceived vertical The tilt induced effect.

• (Nelson Prinzmetal, 2003) - Pitch and roll
  of the visual environment
• contribute independently to visual
  tilt-induced effects.

• (Witkin Asch, 1948) - Tilt-induced effects
  are increased when observers are
• also tilted.

Q3. Do observers actively maintaining an
upright posture on a tilted surface
experience the same degree of visual tilt-induced
effects as passively- tilted observers?
36
Summary of research questions

37
Summary of research questions

Q1. Do pitch and roll of the observer
independently/interactively influence
visual-tilt induced effects?
38
Summary of research questions

Q1. Do pitch and roll of the observer
independently/interactively influence
visual-tilt induced effects?
Q2. Are visual tilt-induced effects really
greater when the observer is tilted
incongruently vs. congruently with the visual
environment?
39
Summary of research questions

Q1. Do pitch and roll of the observer
independently/interactively influence
visual-tilt induced effects?
Q2. Are visual tilt-induced effects really
greater when the observer is tilted
incongruently vs. congruently with the visual
environment?
Q3. Do observers actively maintaining an
upright posture on a tilted surface
experience the same degree of visual tilt-induced
effects as passively- tilted observers?
40
Apparatus for visual tilt-induced effects

41
Apparatus for visual tilt-induced effects

A Rod-Frame box
42
Apparatus for visual tilt-induced effects

A Rod-Frame box
rolled 20o along the roll axis
43
Apparatus for visual tilt-induced effects

A Rod-Frame box
rolled 20o along the roll axis
produced standard visual-tilt induced effects.
44
Perceptual measure
The experimenter rolled the rod independently of
the tilted box until the subject indicated that
the rod was vertical with respect to gravity.
45
Perceptual measure
The experimenter rolled the rod independently of
the tilted box until the subject indicated that
the rod was vertical with respect to gravity.
The deviation from vertical of the observers rod
adjustment (angle of illusion) was measured by a
ruler on the backside of the rod with 0o
corresponding to true vertical position of the
rod.
46
Perceptual measure
A 10o illusion in rod adjustment
47
Perceptual measure
A 10o illusion in rod adjustment
48
Perceptual measure
A 10o illusion in rod adjustment
49
Active observers

• Observers standing on a tilted platform
  actively maintained an upright
• posture

50
Active observers

• Observers standing on a tilted platform
  actively maintained an upright
• posture while determining the vertical
  position of the rod.

51
Active observers

• Observers standing on a tilted platform
  actively maintained an upright
• posture while determining the vertical
  position of the rod.

• The platform could be rotated about an axis on
  the floor to
• pitch and roll the observer.

52
Active observers

• Observers standing on a tilted platform
  actively maintained an upright
• posture while determining the vertical
  position of the rod.

• The platform could be rotated about an axis on
  the floor to
• pitch and roll the observer.
• To control for head tilt,

53
Active observers

• Observers standing on a tilted platform
  actively maintained an upright
• posture while determining the vertical
  position of the rod.

• The platform could be rotated about an axis on
  the floor to
• pitch and roll the observer.
• To control for head tilt, observers were
  instructed to keep the
• head

54
Active observers

• Observers standing on a tilted platform
  actively maintained an upright
• posture while determining the vertical
  position of the rod.

• The platform could be rotated about an axis on
  the floor to
• pitch and roll the observer.
• To control for head tilt, observers were
  instructed to keep the
• head aligned with the upper body.

55
Passive observers

• Passively tilted observers made adjustments

56
Passive observers

• Passively tilted observers made adjustments
  while sitting in a
• chair attached to the tilted platform.

57
Passive observers

• Passively tilted observers made adjustments
  while sitting in a
• chair attached to the tilted platform.

• The chair and platform could be rotated to
  pitch and roll the observer.

58
Passive observers

• Passively tilted observers made adjustments
  while sitting in a
• chair attached to the tilted platform.

• The chair and platform could be rotated to
  pitch and roll the observer.
• Head tilt was controlled using a head rest
  attached to the chair to keep
• the head in line with the upper body.

59
Results n14
Observer Pitch
60
Results n14
Observer Pitch

• There was a standard tilt-induced effect of
  5o in the direction of the
• tilted box.

61
Results n14
Observer Pitch

• Rolling the observer congruently with the box
  slightly increased tilt-
• induced effects.

62
Results n14
Observer Pitch

• Rolling the observer incongruently with the
  box decreased tilt-
• induced effects.

63
Results

• (Witkin Asch, 1948) -

gt
Observers tilted congruently experience larger
tilt-induced effects than incongruently tilted
observers.
(0.8o)
64
Results

• (Witkin Asch, 1948) -

gt
Observers tilted congruently experience larger
tilt-induced effects than incongruently tilted
observers.
(0.8o)
Q2. Are visual tilt-induced effects really
greater when the observer is tilted
incongruently vs. congruently with the visual
environment? (0.8o is pretty weak)
65
Results

• (Witkin Asch, 1948) -

gt
Observers tilted congruently experience larger
tilt-induced effects than incongruently tilted
observers.
(0.8o)
Q2. Are visual tilt-induced effects really
greater when the observer is tilted
incongruently vs. congruently with the visual
environment? (0.8o is pretty weak)
A2. NO!
66
Results

• (Witkin Asch, 1948) -

gt
Observers tilted congruently experience larger
tilt-induced effects than incongruently tilted
observers.
(0.8o)
Q2. Are visual tilt-induced effects really
greater when the observer is tilted
incongruently vs. congruently with the visual
environment? (0.8o is pretty weak)
A2. NO! Visual tilt-induced effects are
slightly increased when the observer is tilted
congruently with the environment and effects are
decreased when the observer is tilted
incongruently with the environment.
lt
67
Results

• (Witkin Asch, 1948) -

gt
Observers tilted congruently experience larger
tilt-induced effects than incongruently tilted
observers.
(0.8o)
Q2. Are visual tilt-induced effects really
greater when the observer is tilted
incongruently vs. congruently with the visual
environment? (0.8o is pretty weak)
A2. NO! Visual tilt-induced effects are
slightly increased when the observer is tilted
congruently with the environment and effects are
decreased when the observer is tilted
incongruently with the environment.
lt
(4o)
68
Results n14
Observer Pitch

• There was no difference between adjustments
  when observers were
• pitched forward or backward. It only
  mattered that they were pitched.

69
Results n14
Observer Pitch

• There was no difference between adjustments
  when observers were
• pitched forward or backward. It only
  mattered that they were pitched.
• The data were collapsed to No Pitch and
  Pitch.

70
Results n14
Observer Pitch

• Pitching observers decreased the standard
  tilt-induced effect.

71
Results n14
Observer Pitch

• Pitching observers exaggerated the
  tilt-induced effects of
• rolling observers.

72
Results

• (Nelson Prinzmetal, 2003) - Pitch and roll
  of the visual environment
• contribute independently to visual
  tilt-induced effects.

73
Results

• (Nelson Prinzmetal, 2003) - Pitch and roll
  of the visual environment
• contribute independently to visual
  tilt-induced effects.
• Manipulating one dimension does not affect the
  influence of the other dimension.

74
Results

• (Nelson Prinzmetal, 2003) - Pitch and roll
  of the visual environment
• contribute independently to visual
  tilt-induced effects.
• Manipulating one dimension does not affect the
  influence of the other dimension.

Q1. Do pitch and roll of the observer
independently/interactively influence
visual-tilt induced effects?
75
Results

• (Nelson Prinzmetal, 2003) - Pitch and roll
  of the visual environment
• contribute independently to visual
  tilt-induced effects.
• Manipulating one dimension does not affect the
  influence of the other dimension.

Q1. Do pitch and roll of the observer
independently/interactively influence
visual-tilt induced effects?
A1. Pitch and roll of the observer interact to
influence the magnitude of visual
tilt-induced effects.
76
Results

• (Nelson Prinzmetal, 2003) - Pitch and roll
  of the visual environment
• contribute independently to visual
  tilt-induced effects.
• Manipulating one dimension does not affect the
  influence of the other dimension.

Q1. Do pitch and roll of the observer
independently/interactively influence
visual-tilt induced effects?
A1. Pitch and roll of the observer interact to
influence the magnitude of visual
tilt-induced effects. Manipulating one dimension
affects the influence of the other dimension.
77
Results n14
Observer Pitch

• Comparing the adjustments of active and
  passive observers.

78
Results n7
Observer Pitch

• Tilt-induced effects were exaggerated for
  passive observers.

79
Results n7
Observer Pitch

• Tilt-induced effects were greatly attenuated
  for active observers.

80
Results
Q3. Do observers actively maintaining an upright
posture on a tilted surface experience the
same degree of visual tilt-induced effects as
passively- tilted observers?
81
Results
Q3. Do observers actively maintaining an upright
posture on a tilted surface experience the
same degree of visual tilt-induced effects as
passively- tilted observers?
A3. No!
82
Results
Q3. Do observers actively maintaining an upright
posture on a tilted surface experience the
same degree of visual tilt-induced effects as
passively- tilted observers?
A3. No! Observers actively maintaining an
upright posture experience enhanced
tilt-induced effects and passively tilted
observers experience weakened tilt-induced
effects.
83
Summary
84
Summary
Q1. Do pitch and roll of the observer
independently/interactively influence
visual-tilt induced effects?
85
Summary
Q1. Do pitch and roll of the observer
independently/interactively influence
visual-tilt induced effects?
A1. Pitch and roll of the observer interact to
influence the magnitude of visual
tilt-induced effects.
86
Summary
Q1. Do pitch and roll of the observer
independently/interactively influence
visual-tilt induced effects?
A1. Pitch and roll of the observer interact to
influence the magnitude of visual
tilt-induced effects.
Q2. Are visual tilt-induced effects really
greater when the observer is tilted
incongruently vs. congruently with the visual
environment?
87
Summary
Q1. Do pitch and roll of the observer
independently/interactively influence
visual-tilt induced effects?
A1. Pitch and roll of the observer interact to
influence the magnitude of visual
tilt-induced effects.
Q2. Are visual tilt-induced effects really
greater when the observer is tilted
incongruently vs. congruently with the visual
environment?
A2. NO! Visual tilt-induced effects are
slightly increased when the observer is
tilted congruently with the environment and
effects are decreased when the observer
is tilted incongruently with the environment.
88
Summary
Q1. Do pitch and roll of the observer
independently/interactively influence
visual-tilt induced effects?
A1. Pitch and roll of the observer interact to
influence the magnitude of visual
tilt-induced effects.
Q2. Are visual tilt-induced effects really
greater when the observer is tilted
incongruently vs. congruently with the visual
environment?
A2. NO! Visual tilt-induced effects are
slightly increased when the observer is
tilted congruently with the environment and
effects are decreased when the observer
is tilted incongruently with the environment.
Q3. Do observers actively maintaining an upright
posture on a tilted surface experience the
same degree of visual tilt-induced effects as
passively- tilted observers?
89
Summary
Q1. Do pitch and roll of the observer
independently/interactively influence
visual-tilt induced effects?
A1. Pitch and roll of the observer interact to
influence the magnitude of visual
tilt-induced effects.
Q2. Are visual tilt-induced effects really
greater when the observer is tilted
incongruently vs. congruently with the visual
environment?
A2. NO! Visual tilt-induced effects are
slightly increased when the observer is
tilted congruently with the environment and
effects are decreased when the observer
is tilted incongruently with the environment.
Q3. Do observers actively maintaining an upright
posture on a tilted surface experience the
same degree of visual tilt-induced effects as
passively- tilted observers?
A3. No! Observers actively maintaining an
upright posture experience enhanced
tilt-induced effects and passively tilted
observers experience weakened tilt-induced
effects.
90
Implications
91
Implications 1
Pitch and roll of the visual environment
independently contribute to visual tilt-induced
effects. (Nelson Prinzmetal, 2003).
92
Implications 1
Pitch and roll of the visual environment
independently contribute to visual tilt-induced
effects. (Nelson Prinzmetal, 2003). Pitching
and rolling the observer and not the visual
environment does nothing (Witkin Asch,
1948).
93
Implications 1
Pitch and roll of the visual environment
independently contribute to visual tilt-induced
effects. (Nelson Prinzmetal, 2003). Pitching
and rolling the observer and not the visual
environment does nothing (Witkin Asch,
1948). Proprioceptive pitch and roll interact
in contributing to visual tilt-induced
effects (current study).
94
Implications 1
Pitch and roll of the visual environment
independently contribute to visual tilt-induced
effects. (Nelson Prinzmetal, 2003). Pitching
and rolling the observer and not the visual
environment does nothing (Witkin Asch,
1948). Proprioceptive pitch and roll interact
in contributing to visual tilt-induced
effects (current study). People weight multiple
sources of information differently depending upon
what you do to them.
95
Implications 1
Pitch and roll of the visual environment
independently contribute to visual tilt-induced
effects. (Nelson Prinzmetal, 2003). Pitching
and rolling the observer and not the visual
environment does nothing (Witkin Asch,
1948). Proprioceptive pitch and roll interact
in contributing to visual tilt-induced
effects (current study). People weight multiple
sources of information differently depending upon
what you do to them. Visual information about
upright modulates the contributions of
proprioceptive cues to gravity.
96
Implications 2
Tipping people the opposite way as the frame
produces the largest tilt-induced effects (Asch
Witkin, 1948).
97
Implications 2
Tipping people the opposite way as the frame
produces the largest tilt-induced effects (Asch
Witkin, 1948). Too small! Not significant!
98
Implications 2
Tipping people the opposite way as the frame
produces the largest tilt-induced effects (Asch
Witkin, 1948). Too small! Not
significant! Tipping people the same way as the
frame produces the largest tilt-induced
effects (current study).
99
Implications 2
Tipping people the opposite way as the frame
produces the largest tilt-induced effects (Asch
Witkin, 1948). Too small! Not
significant! Tipping people the same way as the
frame produces the largest tilt-induced
effects (current study). When visual and
proprioceptive input coincide, observers rely
heaviest on vision to determine upright.
100
Implications 2
Tipping people the opposite way as the frame
produces the largest tilt-induced effects (Asch
Witkin, 1948). Too small! Not
significant! Tipping people the same way as the
frame produces the largest tilt-induced
effects (current study). When visual and
proprioceptive input coincide, observers rely
heaviest on vision to determine upright. When
visual and proprioceptive information are
mismatched, observers try to compensate for
being tilted and rely less on vision to
determine upright.
101
Implications 2
Tipping people the opposite way as the frame
produces the largest tilt-induced effects (Asch
Witkin, 1948). Too small! Not
significant! Tipping people the same way as the
frame produces the largest tilt-induced
effects (current study). When visual and
proprioceptive input coincide, observers rely
heaviest on vision to determine upright. When
visual and proprioceptive information are
mismatched, observers try to compensate for
being tilted and rely less on vision to
determine upright. The more similar the
proprioceptive and visual input,the greater the
illusion.
102
Implications 3
The literature is all over the place regarding
the tilt-induced effects for passive and active
observers.
103
Implications 3
The literature is all over the place regarding
the tilt-induced effects for passive and active
observers. Tilt-induced effects are
attenuated for active observers (current study).
104
Implications 3
The literature is all over the place regarding
the tilt-induced effects for passive and active
observers. Tilt-induced effects are
attenuated for active observers (current
study). Tilt-induced effects are exaggerated for
passive observers (current study).
105
Implications 3
The literature is all over the place regarding
the tilt-induced effects for passive and active
observers. Tilt-induced effects are
attenuated for active observers (current
study). Tilt-induced effects are exaggerated for
passive observers (current study). The less
informative the proprioceptive input, (passive
observers and incongruently tilted observers),
the greater the dependence on visual input, the
greater the tilt-induced effects.
106
Take home message
107
Take home message
If you go inside one of the Mystery Cabins,
108
Take home message
If you go inside one of the Mystery Cabins,
Gold Hill, OR
109
Take home message
If you go inside one of the Mystery Cabins,
Gold Hill, OR
Santa Cruz, CA
110
Take home message
If you go inside one of the Mystery Cabins,
111
Take home message
If you go inside one of the Mystery Cabins,
sit in a chair!!
112
Thanks to
Jim Enns The Oregon Vortex (www.oregonvortex.com)
Bill Prinzmetal Bruce Bridgeman Lovely
assistant Jess Everyone who participated Everyon
e who put up with a huge contraption in their
space Master carpenter, Ken Keltner
113
Questions
Observer Pitch
n14
114
Questions
n7
115
Questions
n7