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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.

Jennifer E. Corbett & James T. Enns

The University of British Columbia

6/4/04


Vision and proprioception calibrate our sense of upright.


Vision and proprioception calibrate our sense of upright.

  • We rely on:

  • Visual orientation cues


Vision and proprioception calibrate our sense of upright.

  • We rely on:

  • Visual orientation cues


Vision and proprioception calibrate our sense of upright.

  • We rely on:

  • Visual orientation cues

  • &

  • Proprioception


Vision and proprioception calibrate our sense of upright.

  • We rely on:

  • Visual orientation cues

  • &

  • Proprioception


Vision and proprioception calibrate our sense of upright.

  • We rely on:

  • Visual orientation cues

  • &

  • Proprioception

To determine our

perceptions of upright.


A fun example: Mystery Spots


Mystery Spots

Vision


Mystery Spots

Vision +Proprioception


Mystery Spots

Vision +Proprioception

Upright


In the present study…


In the present study…

How does rolling

Roll


In the present study…

How does rolling

Roll


In the present study…

How does rolling

Roll


In the present study…

How does rolling and pitching the observer

Pitch


In the present study…

How does rolling and pitching the observer

Pitch


In the present study…

How does rolling and pitching the observer

Pitch


Pitch

Roll

In the present study…

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


In the present study…

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

Pitch

Roll


Introduction


Introduction

  • (Asch & Witkin, 1948)


Introduction

  • (Asch & Witkin, 1948)

True vertical


Introduction

  • (Asch & Witkin, 1948)

Visual tilt

True vertical


Introduction

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

Perceived vertical

Visual tilt

True vertical


Introduction

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

  • tilt-induced effects.


Introduction

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

  • tilt-induced effects.

Untilted observers


<

Tilt-induced effects

Introduction

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

  • tilt-induced effects.

Untilted observers

Congruently tilted

observers


<

<

Tilt-induced effects

Tilt-induced effects

Introduction

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

  • tilt-induced effects.

Untilted observers

Congruently tilted

observers

Incongruently tilted

observers


<

<

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


Introduction

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

Q1. What really happens to tilt-induced effects when

observers are tilted?


Introduction

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

  • are additive.


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?


Introduction

Q3. Does it matter whether observers are actively

maintaining an upright posture on a tilted surface

or whether they are passively tilted?


Summary of research questions


Summary of research questions

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

For incongruently tilted observers?


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?


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?


Apparatus for visual tilt-induced effects


Apparatus for visual tilt-induced effects

A Rod-Frame box


Apparatus for visual tilt-induced effects

A Rod-Frame box

rolled 20o along the roll axis


Apparatus for visual tilt-induced effects

A Rod-Frame box

rolled 20o along the roll axis

produced standard visual-tilt induced effects.


Perceptual measure

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


Perceptual measure

Angle of illusion


Perceptual measure

A 10o illusion in rod adjustment:


Perceptual measure

A 10o illusion in rod adjustment:


Perceptual measure

A 10o illusion in rod adjustment:


Active observers

  • Tilted platform


Active observers

  • Tilted platform + standing observer


Active observers

  • Tilted platform + standing observer

  • Platform rotates to pitch and roll observer.


Active observers

  • Tilted platform + standing observer

  • Platform rotates to pitch and roll observer

  • To control for head tilt


Active observers

  • Tilted platform + standing observer

  • Platform rotates to pitch and roll observer

  • To control for head tilt: head


Active observers

  • Tilted platform + standing observer

  • Platform rotates to pitch and roll observer

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


Passive observers

  • Tilted platform + tilted chair


Passive observers

  • Tilted platform + tilted chair + sitting obsever


Passive observers

  • Tilted platform + tilted chair + sitting observer

  • Chair and platform rotate to pitch and roll observer.


Passive observers

  • Tilted platform + tilted chair + sitting observer

  • Chair and platform rotate to pitch and roll observer.

  • To control for head tilt: Headrest


Resultsn=14

Observer Pitch


Resultsn=14

Observer Pitch

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

  • tilted box.


Resultsn=14

Observer Pitch

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

  • induced effects.


Resultsn=14

Observer Pitch

  • Rolling the observer incongruently with the box decreased tilt-

  • induced effects.


<

<

Tilt-induced effects

Tilt-induced effects

Results

  • (Witkin & Asch, 1948):

Untilted observers

Congruently tilted

observers

Incongruently tilted

observers


<

<

Tilt-induced effects

Tilt-induced effects

Insignificant/incomplete

Results

  • (Witkin & Asch, 1948):

Untilted observers

Congruently tilted

observers

Incongruently tilted

observers


Results

  • (Witkin & Asch, 1948):

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

For incongruently tilted observers?


Results

  • (Witkin & Asch, 1948):

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

For incongruently tilted observers? No!


<

<

<

<

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


<

<

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


Resultsn=14

Observer Pitch

  • There was no difference between adjustments when observers were

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


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.”


Resultsn=14

Observer Pitch

  • Pitching observers decreased the standard tilt-induced effect.


Resultsn=14

Observer Pitch

  • Pitching observers exaggerated the tilt-induced effects of

  • rolling observers.


Results

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

  • contribute independently to visual tilt-induced effects.


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.


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?


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.


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.


Resultsn=14

Observer Pitch

  • Comparing the adjustments of active and passive observers….


Resultsn=7

Observer Pitch

  • Tilt-induced effects were exaggerated for passive observers.


Resultsn=7

Observer Pitch

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


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?


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!


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.


Summary


Summary

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

For incongruently tilted observers?


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.


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?


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.


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?


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.


Implications


Implications1

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

(Asch & Witkin, 1948).


Implications1

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

(Asch & Witkin, 1948).

Not significant! Incomplete! Confounded?


Implications1

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

(Asch & Witkin, 1948).

Not significant! Incomplete! Confounded?

Incongruent < No tilt < Congruent

(current study).


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.


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.


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.


Implications 2

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


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).


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).


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.


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.


Implications3

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

and active observers.


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).


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).


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.


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.


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.


Take home message:


Take home message:

If you go inside one of the Mystery Cabins,


Take home message:

If you go inside one of the Mystery Cabins,

Gold Hill, OR


Take home message:

If you go inside one of the Mystery Cabins,

Gold Hill, OR

Santa Cruz, CA


Take home message:

If you go inside one of the Mystery Cabins,


Take home message:

If you go inside one of the Mystery Cabins,

sit in a chair!!


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


Questions

Observer Pitch

n=14


Questions

n=7


Questions

n=7


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