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

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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


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Vision and proprioception calibrate our sense of upright.


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Vision and proprioception calibrate our sense of upright.

  • We rely on:

  • Visual orientation cues


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Vision and proprioception calibrate our sense of upright.

  • We rely on:

  • Visual orientation cues


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Vision and proprioception calibrate our sense of upright.

  • We rely on:

  • Visual orientation cues

  • &

  • Proprioception


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Vision and proprioception calibrate our sense of upright.

  • We rely on:

  • Visual orientation cues

  • &

  • Proprioception


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Vision and proprioception calibrate our sense of upright.

  • We rely on:

  • Visual orientation cues

  • &

  • Proprioception

To determine our

perceptions of upright.


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A fun example: Mystery Spots


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Mystery Spots

Vision


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Mystery Spots

Vision +Proprioception


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Mystery Spots

Vision +Proprioception

Upright


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In the present study…


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In the present study…

How does rolling

Roll


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In the present study…

How does rolling

Roll


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In the present study…

How does rolling

Roll


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In the present study…

How does rolling and pitching the observer

Pitch


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In the present study…

How does rolling and pitching the observer

Pitch


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In the present study…

How does rolling and pitching the observer

Pitch


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Pitch

Roll

In the present study…

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


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In the present study…

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

Pitch

Roll


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Introduction


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Introduction

  • (Asch & Witkin, 1948)


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Introduction

  • (Asch & Witkin, 1948)

True vertical


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Introduction

  • (Asch & Witkin, 1948)

Visual tilt

True vertical


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Introduction

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

Perceived vertical

Visual tilt

True vertical


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Introduction

  • (Witkin & Asch, 1948): Tilting observers increases

  • tilt-induced effects.


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Introduction

  • (Witkin & Asch, 1948): Tilting observers increases

  • tilt-induced effects.

Untilted observers


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<

Tilt-induced effects

Introduction

  • (Witkin & Asch, 1948): Tilting observers increases

  • tilt-induced effects.

Untilted observers

Congruently tilted

observers


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<

<

Tilt-induced effects

Tilt-induced effects

Introduction

  • (Witkin & Asch, 1948): Tilting observers increases

  • tilt-induced effects.

Untilted observers

Congruently tilted

observers

Incongruently tilted

observers


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<

<

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


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Introduction

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

Q1. What really happens to tilt-induced effects when

observers are tilted?


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Introduction

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

  • are additive.


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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?


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Introduction

Q3. Does it matter whether observers are actively

maintaining an upright posture on a tilted surface

or whether they are passively tilted?


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Summary of research questions


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Summary of research questions

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

For incongruently tilted observers?


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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?


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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?


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Apparatus for visual tilt-induced effects


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Apparatus for visual tilt-induced effects

A Rod-Frame box


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Apparatus for visual tilt-induced effects

A Rod-Frame box

rolled 20o along the roll axis


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Apparatus for visual tilt-induced effects

A Rod-Frame box

rolled 20o along the roll axis

produced standard visual-tilt induced effects.


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Perceptual measure

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


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Perceptual measure

Angle of illusion


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Perceptual measure

A 10o illusion in rod adjustment:


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Perceptual measure

A 10o illusion in rod adjustment:


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Perceptual measure

A 10o illusion in rod adjustment:


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Active observers

  • Tilted platform


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Active observers

  • Tilted platform + standing observer


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Active observers

  • Tilted platform + standing observer

  • Platform rotates to pitch and roll observer.


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Active observers

  • Tilted platform + standing observer

  • Platform rotates to pitch and roll observer

  • To control for head tilt


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Active observers

  • Tilted platform + standing observer

  • Platform rotates to pitch and roll observer

  • To control for head tilt: head


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Active observers

  • Tilted platform + standing observer

  • Platform rotates to pitch and roll observer

  • To control for head tilt: head aligned with upper body.


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Passive observers

  • Tilted platform + tilted chair


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Passive observers

  • Tilted platform + tilted chair + sitting obsever


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Passive observers

  • Tilted platform + tilted chair + sitting observer

  • Chair and platform rotate to pitch and roll observer.


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Passive observers

  • Tilted platform + tilted chair + sitting observer

  • Chair and platform rotate to pitch and roll observer.

  • To control for head tilt: Headrest


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Resultsn=14

Observer Pitch


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Resultsn=14

Observer Pitch

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

  • tilted box.


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Resultsn=14

Observer Pitch

  • Rolling the observer congruently with the box slightly increased tilt-

  • induced effects.


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Resultsn=14

Observer Pitch

  • Rolling the observer incongruently with the box decreased tilt-

  • induced effects.


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<

<

Tilt-induced effects

Tilt-induced effects

Results

  • (Witkin & Asch, 1948):

Untilted observers

Congruently tilted

observers

Incongruently tilted

observers


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<

<

Tilt-induced effects

Tilt-induced effects

Insignificant/incomplete

Results

  • (Witkin & Asch, 1948):

Untilted observers

Congruently tilted

observers

Incongruently tilted

observers


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Results

  • (Witkin & Asch, 1948):

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

For incongruently tilted observers?


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Results

  • (Witkin & Asch, 1948):

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

For incongruently tilted observers? No!


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<

<

<

<

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


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<

<

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


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Resultsn=14

Observer Pitch

  • There was no difference between adjustments when observers were

  • pitched forward or backward. It only mattered that they were pitched.


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Resultsn=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.”


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Resultsn=14

Observer Pitch

  • Pitching observers decreased the standard tilt-induced effect.


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Resultsn=14

Observer Pitch

  • Pitching observers exaggerated the tilt-induced effects of

  • rolling observers.


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Results

  • (Nelson & Prinzmetal, 2003) - Pitch and roll of the visual environment

  • contribute independently to visual tilt-induced effects.


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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.


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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?


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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.


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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.


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Resultsn=14

Observer Pitch

  • Comparing the adjustments of active and passive observers….


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Resultsn=7

Observer Pitch

  • Tilt-induced effects were exaggerated for passive observers.


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Resultsn=7

Observer Pitch

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


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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?


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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!


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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.


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Summary


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Summary

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

For incongruently tilted observers?


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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.


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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?


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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.


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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?


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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.


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Implications


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Implications1

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

(Asch & Witkin, 1948).


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Implications1

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

(Asch & Witkin, 1948).

Not significant! Incomplete! Confounded?


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Implications1

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

(Asch & Witkin, 1948).

Not significant! Incomplete! Confounded?

Incongruent < No tilt < Congruent

(current study).


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Implications1

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.


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Implications1

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.


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Implications1

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.


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Implications 2

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


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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).


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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).


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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.


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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.


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Implications3

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

and active observers.


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Implications3

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).


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Implications3

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).


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Implications3

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.


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Implications3

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.


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Implications3

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.


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Take home message:


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Take home message:

If you go inside one of the Mystery Cabins,


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Take home message:

If you go inside one of the Mystery Cabins,

Gold Hill, OR


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Take home message:

If you go inside one of the Mystery Cabins,

Gold Hill, OR

Santa Cruz, CA


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Take home message:

If you go inside one of the Mystery Cabins,


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Take home message:

If you go inside one of the Mystery Cabins,

sit in a chair!!


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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


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Questions

Observer Pitch

n=14


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Questions

n=7


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Questions

n=7


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