Scene perception

9.1 Scene Perception
PSYC 579 Topic Presentation,
University of British Columbia
Diliara Nasirova
School of Interactive Art and Technology,
Simon Fraser University
March 23, 2011

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Outline
1.  Introduction to Scene Perception
2.  Theories of Scene Perception
■  Coherence Theory
■  Virtual Representation
■  Triadic Architecture
3.  Application to visual design
■  Visual Transitions
■  Attentional Coercion
Diliara Nasirova | PSYC 579 | March 23, 2011

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Introduction
Scene Perception
•  Scene Perception is a visual perception of an environment as viewed by
an observer at any given time.

4
Introduction
Belief about vision
•  Our brains contain detailed, picture-like representation of the scene

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Introduction
Phenomena against the belief
•  Inattentional Blindness:
•  The failure to notice the presence
of unattended stimuli, even when
they are presented within an
observer’s field of view
•  Change Blindness:
•  The failure to see changes even
when they are large, anticipated
and repeatedly made if they are
made during a visual disturbance
Simons and Chabris (1999) “Gorillas in Our Midst:
Sustained Inattentional Blindness for Dynamic Events”

6
Introduction
Phenomena against the belief
•  Inattentional Blindness:
•  The failure to notice the presence
of unattended stimuli, even when
they are presented within an
observer’s field of view
•  Change Blindness:
•  The failure to see changes even
when they are large, anticipated
and repeatedly made if they are
made during a visual disturbance
Rensink RA (2002). Internal vs. external information in
visual perception.

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Introduction
Change Blindness demo
http://www.cs.ubc.ca/~rensink/flicker/download/Harborside.mov

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Introduction

9
Introduction

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Introduction

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Introduction
If a visual buffer existed…

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Introduction
If there is no buffer…
1.  How is it possible to see change at all?
2.  How might human vision operate?

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Theories of Scene Perception
Coherence theory
•  Coherence theory is based on three related hypotheses
1.  Volatile proto-objects formed rapidly in the visual field (without attention)
2.  Focused attention selects some proto-objects and forms coherence field
3.  Release of focused attention (back to proto-objects)

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Coherence theory
2. Focused attention selects some proto-objects and forms coherence field
3. Release of focused attention (back to proto-objects)

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Coherence theory
2.  Focused attention selects some proto-objects and forms coherence field
3.  Release of focused attention (back to proto-objects)

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Coherence theory
•  Why observers fail to detect changes in "attended" objects?
■  Small number of items can be attended at any time
■  Not all details can be represented in a coherence field
■  Change blindness results

Coherence theory
•  Counterintuitive implications:
■  Only a few items can be
represented
■  The representation details is
limited
•  Why do we not notice these
limitations?
Rensink RA (2000a). The dynamic representation of scenes.

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Virtual Representation
•  For most tasks, only one object is in play at any time:

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•  Idea of virtual representation:
■  Create a coherent, detailed
representation only of a few objects
needed for the task at hand
■  Details about any object should be
available on request
•  Provide large savings in computational
resources: memory & processing time

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•  For successful use of virtual representation
eye movements and attentional shifts should
be made
■  to the appropriate object
■  at the appropriate time.
•  But what directs these movements and shifts?
Rensink RA (2000). Scene perception.

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Triadic Architecture
•  A possible solution is a triadic architecture with three systems
Rensink RA (2000). Scene perception.
layout
gist
object
sketch

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Rensink RA (2002). Internal vs. external information in visual perception.

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•  The representation of a scene
involves the dynamic interaction of
three systems.
•  A complete representation of the
scene is never constructed - only
one coherent object represented at
any one time

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Application to Visual Design
Visual Transitions
•  It is possible for displays to
promote or prevent the conditions
that create change blindness.
■  Saccade
■  Eye blinks
■  Occlusion
■  Movie cuts
■  Gradual transitions
■  Movement
Diliara Nasirova | PSYC 579 | Jan 26, 2011

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Visual Transitions
Diliara Nasirova | PSYC 579 | Jan 26, 2011
•  Design of displays robust to change
blindness:
■  Minimizing saccades (important
information close together)
■  Minimizing number of dynamic
events in the background &
foreground

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Visual Transitions
•  Change Detection in 3D
Parametric Systems:
Human-Centered Interfaces
for Change Visualization
1. Change blindness
2. On model (A) and
on periphery (B)
visualizations
3. Combined views.
http://www.bentley.com/

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Visual Transitions
•  Change Detection in 3D
Parametric Systems:
Human-Centered Interfaces
for Change Visualization
1. Change blindness
2. On model (A) and
on periphery (B)
visualizations
3. Combined views.

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Attention Coercion
•  Taking control of attention and
making the observer see (or not
see) any given part of the display.
•  Can be carried out in different ways:
■  High-level interest

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Attention Coercion
■  Mid-level directives

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Attention Coercion
■  Mid-level directives
■  Low-level salience

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Conclusion
1.  Change blindness is very general
phenomenon.
2.  Only one coherent object can be
attended at a time.
3.  The perception of a scene is inherently
dynamic.

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Questions?
•  Thank you…

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References
1.  Rensink RA (2002). Internal vs. external information in visual perception.
Proceedings of the Second International Symposium on Smart Graphics: 63-70.
[Smart Graphics 2; Hawthorne, NY, USA.]
2.  Rensink RA (2000). Scene perception. In AE Kazdin (ed.), Encyclopedia of
Psychology, vol. 7. (pp. 151-155). New York: Oxford University Press.
3.  Rensink RA (2000a). The dynamic representation of scenes. In DJ Simons (ed.)
Change Blindness and Visual Memory (pp. 17-42). London: Psychology Press.
4.  Varakin DA, Levin DT, and Fidler R (2008). Unseen and unaware: implications of
recent research on failures of visual awareness for human-computer interface
design. Hum.-Comput. Interact., 19:389–422

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