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The contributions of proprioceptive pitch and roll to visual tilt-induced effects for active and passive observers. Jennifer E. Corbett & James T. Enns The University of British Columbia 6/4/04 Vision and proprioception calibrate our sense of upright.

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slide1
The contributions of proprioceptive pitch and roll to visual tilt-induced effects for active and passive observers.

Jennifer E. Corbett & James T. Enns

The University of British Columbia

6/4/04

vision and proprioception calibrate our sense of upright5
Vision and proprioception calibrate our sense of upright.
  • We rely on:
  • Visual orientation cues
  • &
  • Proprioception
vision and proprioception calibrate our sense of upright6
Vision and proprioception calibrate our sense of upright.
  • We rely on:
  • Visual orientation cues
  • &
  • Proprioception
vision and proprioception calibrate our sense of upright7
Vision and proprioception calibrate our sense of upright.
  • We rely on:
  • Visual orientation cues
  • &
  • Proprioception

To determine our

perceptions of upright.

slide10

Mystery Spots

Vision + Proprioception

slide11

Mystery Spots

Vision + Proprioception

Upright

in the present study13
In the present study…

How does rolling

Roll

in the present study14
In the present study…

How does rolling

Roll

in the present study15
In the present study…

How does rolling

Roll

in the present study16
In the present study…

How does rolling and pitching the observer

Pitch

in the present study17
In the present study…

How does rolling and pitching the observer

Pitch

in the present study18
In the present study…

How does rolling and pitching the observer

Pitch

in the present study19

Pitch

Roll

In the present study…

How does rolling and pitching the observer interact with visual orientation cues

in the present study20
In the present study…

How does rolling and pitching the observer interact with visual orientation cues to produce observers’ perceptions of upright?

Pitch

Roll

slide22

Introduction

  • (Asch & Witkin, 1948)
slide23

Introduction

  • (Asch & Witkin, 1948)

True vertical

slide24

Introduction

  • (Asch & Witkin, 1948)

Visual tilt

True vertical

slide25

Introduction

  • (Asch & Witkin, 1948):Tilt-induced effects

Perceived vertical

Visual tilt

True vertical

slide26

Introduction

  • (Witkin & Asch, 1948): Tilting observers increases
  • tilt-induced effects.
slide27

Introduction

  • (Witkin & Asch, 1948): Tilting observers increases
  • tilt-induced effects.

Untilted observers

slide28

<

Tilt-induced effects

Introduction

  • (Witkin & Asch, 1948): Tilting observers increases
  • tilt-induced effects.

Untilted observers

Congruently tilted

observers

slide29

<

<

Tilt-induced effects

Tilt-induced effects

Introduction

  • (Witkin & Asch, 1948): Tilting observers increases
  • tilt-induced effects.

Untilted observers

Congruently tilted

observers

Incongruently tilted

observers

slide30

<

<

Tilt-induced effects

Tilt-induced effects

Introduction

  • (Witkin & Asch, 1948): Tilting observers increases
  • tilt-induced effects.

Untilted observers

Congruently tilted

observers

Incongruently tilted

observers

0.8o

slide31

Introduction

  • (Witkin & Asch, 1948): Tilting observers increases tilt-induced effects.

Q1. What really happens to tilt-induced effects when

observers are tilted?

slide32

Introduction

  • (Nelson & Prinzmetal, 2003): In vision, pitch and roll
  • are additive.
slide33

Introduction

  • (Nelson & Prinzmetal, 2003): In vision, pitch and roll are additive.

Q2. Do pitch and roll of the observer independently/

interactively influence visual-tilt induced effects?

slide34

Introduction

Q3. Does it matter whether observers are actively

maintaining an upright posture on a tilted surface

or whether they are passively tilted?

slide36

Summary of research questions

Q1. Are visual tilt-induced effects really greater for tilted observers?

For incongruently tilted observers?

slide37

Summary of research questions

Q1. Are visual tilt-induced effects really greater for tilted observers?

For incongruently tilted observers?

Q2. Do pitch and roll of the observer independently/interactively influence

visual-tilt induced effects?

slide38

Summary of research questions

Q1. Are visual tilt-induced effects really greater for tilted observers?

For incongruently tilted observers?

Q2. Do pitch and roll of the observer independently/interactively influence

visual-tilt induced effects?

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?

slide41

Apparatus for visual tilt-induced effects

A Rod-Frame box

rolled 20o along the roll axis

slide42

Apparatus for visual tilt-induced effects

A Rod-Frame box

rolled 20o along the roll axis

produced standard visual-tilt induced effects.

slide43

Perceptual measure

“Say when the rod is vertical with respect to gravity”

slide44

Perceptual measure

Angle of illusion

slide45

Perceptual measure

A 10o illusion in rod adjustment:

slide46

Perceptual measure

A 10o illusion in rod adjustment:

slide47

Perceptual measure

A 10o illusion in rod adjustment:

slide48

Active observers

  • Tilted platform
slide49

Active observers

  • Tilted platform + standing observer
slide50

Active observers

  • Tilted platform + standing observer
  • Platform rotates to pitch and roll observer.
slide51

Active observers

  • Tilted platform + standing observer
  • Platform rotates to pitch and roll observer
  • To control for head tilt
slide52

Active observers

  • Tilted platform + standing observer
  • Platform rotates to pitch and roll observer
  • To control for head tilt: head
slide53

Active observers

  • Tilted platform + standing observer
  • Platform rotates to pitch and roll observer
  • To control for head tilt: head aligned with upper body.
slide54

Passive observers

  • Tilted platform + tilted chair
slide55

Passive observers

  • Tilted platform + tilted chair + sitting obsever
slide56

Passive observers

  • Tilted platform + tilted chair + sitting observer
  • Chair and platform rotate to pitch and roll observer.
slide57

Passive observers

  • Tilted platform + tilted chair + sitting observer
  • Chair and platform rotate to pitch and roll observer.
  • To control for head tilt: Headrest
slide58

Results n=14

Observer Pitch

slide59

Results n=14

Observer Pitch

  • There was a standard tilt-induced effect of ~5o in the direction of the
  • tilted box.
slide60

Results n=14

Observer Pitch

  • Rolling the observer congruently with the box slightly increased tilt-
  • induced effects.
slide61

Results n=14

Observer Pitch

  • Rolling the observer incongruently with the box decreased tilt-
  • induced effects.
slide62

<

<

Tilt-induced effects

Tilt-induced effects

Results

  • (Witkin & Asch, 1948):

Untilted observers

Congruently tilted

observers

Incongruently tilted

observers

slide63

<

<

Tilt-induced effects

Tilt-induced effects

Insignificant/incomplete

Results

  • (Witkin & Asch, 1948):

Untilted observers

Congruently tilted

observers

Incongruently tilted

observers

slide64

Results

  • (Witkin & Asch, 1948):

Q1. Are visual tilt-induced effects really greater for tilted observers?

For incongruently tilted observers?

slide65

Results

  • (Witkin & Asch, 1948):

Q1. Are visual tilt-induced effects really greater for tilted observers? some

For incongruently tilted observers? No!

slide66

<

<

<

<

Tilt-induced effects

Tilt-induced effects

Tilt-induced effects

Tilt-induced effects

Results

  • (Witkin & Asch, 1948):

Untilted observers

Congruently tilted

observers

Incongruently tilted

observers

  • Current study:

Incongruently tilted

observers

Untilted observers

Congruently tilted

observers

slide67

<

<

Tilt-induced effects

Tilt-induced effects

Results

A1: Tilt-induced effects are decreased for

incongruent observers and increased for

congruent observers.

  • Current study:

Incongruently tilted

observers

Untilted observers

Congruently tilted

observers

slide68

Results n=14

Observer Pitch

  • There was no difference between adjustments when observers were
  • pitched forward or backward. It only mattered that they were pitched.
slide69

Results n=14

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.”
slide70

Results n=14

Observer Pitch

  • Pitching observers decreased the standard tilt-induced effect.
slide71

Results n=14

Observer Pitch

  • Pitching observers exaggerated the tilt-induced effects of
  • rolling observers.
slide72

Results

  • (Nelson & Prinzmetal, 2003) - Pitch and roll of the visual environment
  • contribute independently to visual tilt-induced effects.
slide73

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.
slide74

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.

Q2. Do pitch and roll of the observer independently/interactively influence

visual-tilt induced effects?

slide75

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.

Q2. Do pitch and roll of the observer independently/interactively influence

visual-tilt induced effects?

A2. Pitch and roll of the observer interact to influence the magnitude of

visual tilt-induced effects.

slide76

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.

Q2. Do pitch and roll of the observer independently/interactively influence

visual-tilt induced effects?

A2. 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.

slide77

Results n=14

Observer Pitch

  • Comparing the adjustments of active and passive observers….
slide78

Results n=7

Observer Pitch

  • Tilt-induced effects were exaggerated for passive observers.
slide79

Results n=7

Observer Pitch

  • Tilt-induced effects were greatly attenuated for active observers.
slide80

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?

slide81

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!

slide82

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

weakened tilt-induced effects and passively tilted observers experience

enhanced tilt-induced effects.

slide84

Summary

Q1. Are visual tilt-induced effects really greater for tilted observers?

For incongruently tilted observers?

slide85

Summary

Q1. Are visual tilt-induced effects really greater for tilted observers? some

For incongruently tilted observers? No!

A1: Tilt-induced effects are decreased for incongruent observers and

increased for congruent observers.

slide86

Summary

Q1. Are visual tilt-induced effects really greater for tilted observers? some

For incongruently tilted observers? No!

A1: Tilt-induced effects are decreased for incongruent observers and

increased for congruent observers.

Q2. Do pitch and roll of the observer independently/interactively influence

visual-tilt induced effects?

slide87

Summary

Q1. Are visual tilt-induced effects really greater for tilted observers? some

For incongruently tilted observers? No!

A1: Tilt-induced effects are decreased for incongruent observers and

increased for congruent observers.

Q2. Do pitch and roll of the observer independently/interactively influence

visual-tilt induced effects?

A2. Pitch and roll of the observer interact to influence the magnitude of

visual tilt-induced effects.

slide88

Summary

Q1. Are visual tilt-induced effects really greater for tilted observers? some

For incongruently tilted observers? No!

A1: Tilt-induced effects are decreased for incongruent observers and

increased for congruent observers.

Q2. Do pitch and roll of the observer independently/interactively influence

visual-tilt induced effects?

A2. Pitch and roll of the observer interact to influence the magnitude of

visual tilt-induced effects.

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?

slide89

Summary

Q1. Are visual tilt-induced effects really greater for tilted observers? some

For incongruently tilted observers? No!

A1: Tilt-induced effects are decreased for incongruent observers and

increased for congruent observers.

Q2. Do pitch and roll of the observer independently/interactively influence

visual-tilt induced effects?

A2. Pitch and roll of the observer interact to influence the magnitude of

visual tilt-induced effects.

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

weakened tilt-induced effects and passively tilted observers experience

enhanced tilt-induced effects.

slide91

Implications 1

Tilted observers, increased tilt-induced effects. Greatest for incongruent observers

(Asch & Witkin, 1948).

slide92

Implications 1

Tilted observers, increased tilt-induced effects. Greatest for incongruent observers

(Asch & Witkin, 1948).

Not significant! Incomplete! Confounded?

slide93

Implications 1

Tilted observers, increased tilt-induced effects. Greatest for incongruent observers

(Asch & Witkin, 1948).

Not significant! Incomplete! Confounded?

Incongruent < No tilt < Congruent

(current study).

slide94

Implications 1

Tilted observers, increased tilt-induced effects. Greatest for incongruent observers

(Asch & Witkin, 1948).

Not significant! Incomplete! Confounded?

Incongruent < No tilt < Congruent

(current study).

Vision  Proprioception, use vision less.

slide95

Implications 1

Tilted observers, increased tilt-induced effects. Greatest for incongruent observers

(Asch & Witkin, 1948).

Not significant! Incomplete! Confounded?

Incongruent < No tilt < Congruent

(current study).

Vision  Proprioception, use vision less.

Vision = Proprioception, use vision most.

slide96

Implications 1

Tilted observers, increased tilt-induced effects. Greatest for incongruent observers

(Asch & Witkin, 1948).

Not significant! Incomplete! Confounded?

Incongruent < No tilt < Congruent

(current study).

Vision  Proprioception, use vision less.

Vision = Proprioception, use vision most.

The more similar the proprioceptive and visual

input,the greater the illusion.

slide97

Implications 2

In vision pitch and roll are independent. (Nelson & Prinzmetal, 2003).

slide98

Implications 2

In vision pitch and roll are independent. (Nelson & Prinzmetal, 2003).

Pitching and rolling the observer and not the visual environment does nothing

(Witkin & Asch, 1948).

slide99

Implications 2

In vision pitch and roll are independent. (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).

slide100

Implications 2

In vision pitch and roll are independent. (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.

slide101

Implications 2

In vision pitch and roll are independent. (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.

slide102

Implications 3

The literature is all over the place regarding the tilt-induced effects for passive

and active observers.

slide103

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).

slide104

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).

slide105

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).

Weak proprioception (passive) more vision.

slide106

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).

Weak proprioception (passive) more vision.

Strong proprioception (active) less vision.

slide107

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).

Weak proprioception (passive) more vision.

Strong proprioception (active) less vision.

The more informative proprioception,

the less vision.

slide109

Take home message:

If you go inside one of the Mystery Cabins,

slide110

Take home message:

If you go inside one of the Mystery Cabins,

Gold Hill, OR

slide111

Take home message:

If you go inside one of the Mystery Cabins,

Gold Hill, OR

Santa Cruz, CA

slide112

Take home message:

If you go inside one of the Mystery Cabins,

slide113

Take home message:

If you go inside one of the Mystery Cabins,

sit in a chair!!

slide114

Thanks to

Jim Enns

The Oregon Vortex (www.oregonvortex.com)

Bill Prinzmetal

Bruce Bridgeman

Lovely assistant Jess

Everyone who participated

Everyone who put up with a huge contraption in their space

Master carpenter, Ken Keltner

slide115

Questions

Observer Pitch

n=14