Engineering Psychology PSY 378S

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Engineering PsychologyPSY 378S

• University of Toronto
• Spring 2004
• L9 Spatial Displays II
• Compatibility, Depth and Distance

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Outline

• Dynamic displays
• Display compatibility
• Principal of pictorial realism (static)
• Principal of moving part (dynamic)
• Frequency separated display
• Ecological interface design
• Depth cues and depth in displays

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Dynamic Displays

• Dials, Meters, Indicators
• Represent Current State of Dynamic System
• Now Introducing a Dynamic Component into
  Graphical Representation

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Display Compatibility

• As with graphs, should be compatibility between
  display and users internal representation--mental
  model

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Display Compatibility

• But display also should be compatible with
  dynamic system itself (ecological compatibility,
  Vicente 1990, 1997)
• Compatibility now three-way more complex

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Static and Dynamic

• Complex systems change over time
• Because system dynamic, can now divide display
  compatibility into static and dynamic components

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Principle of Pictorial Realism

• Display Representation Should Look Like--Be a
  Pictorial Representation of--What it Represents
• Two Components
• If system variable analog, display should be
  analog
• Direction and shape of display should be
  compatible with system variables (e.g.,
  altimeter)
• and users mental representation (e.g.,
  thermometer)
• Static Principle

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Altimeter Puzzle

• Altitude is analog (big changes more important
  than small)
• But altitude has a direction, is continuous
• Why do conventional altimeters decompose altitude
  into components (or use digits)?

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Principle of the Moving Part

• Direction and movement of an indicator on a
  display should be compatible with the direction
  of physical movement (and operators mental
  model)
• Dynamic principle

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• Moving pointer display (a) follows principle of
  pictorial realism
• But can only show a small range of values

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• Solution is moving scale display
• Moving scale display (b) follows principle of
  pictorial realism, but violates principle of
  moving part
• Moving scale display (c) does the reverse

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• Better solution is a hybrid display
• Quick movement of pointer (moves up with
  aircraft, following principle of moving part),
  slower adjustment of pictorially realistic scale
  shown in (a)
• Both principles satisfied

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Perception of Tilt (Attitude) Attitude Indicators

• Inside-out (a) and Outside-in (b) Displays (a)
  is the convention
• (a) follows principle of pictorial realism (how
  it appears in the cockpit)
• Problem principal of moving part says aircraft
  is moving, so the aircraft symbol on the attitude
  display should move too
• But whats moving on inside-out display--the
  horizon!

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Attitude Indicators

• But whats moving on inside-out display--the
  horizon!
• Violates principle of the moving part
• Solution is another frequency-separated display

• In (b), When aircraft makes quick movement, so
  does symbol on display
• In (c) the horizon tilts more slowly, so we end
  up with (a)

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Right Principle at Right Time

• For fast responses, when control movement and
  motion perception are dominant, principle of
  moving part followed
• But when attitude relatively static (plane
  banked), principle of pictorial realism followed

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Why Bother?

• Because of the phenomenon of a roll-control
  reversal
• With (a), Pilot may perceive the moving display
  element (horizon) as the aircraft, and try to
  control its orientation
• Roscoe (1992) estimates about 100 fatalities/year
  in the U.S. due to roll-control reversal

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Death Spiral

• Aircraft, if left alone, wants to start
  turning, although very slowly
• When wing drops, nose goes down, airspeed
  increases
• Changes in attitude occur very slowly, our
  vestibular system does not respond well
• If pilot not attending, first thing will notice
  is the airspeed increasing

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Death Spiral (contd)

• Action? Pull up to slow airspeed
• Butthis will heighten the spiral motion, with
  grave consequences
• When pilot determines its an attitude problem,
  ends up controlling horizon
• Solution level the wings with slow rudder
  pressure
• Design solution frequency separated display will
  show aircraft motion in response to control

www.avweb.com/articles/spiral/
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Ecological Interface Design

• When display configuration reflects constraints
  of physical system, it is called an ecological
  interface (Vicente Rasmussen, 1992)
• When information is strategically arranged,
  emergent features can arise

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Example of Ecological Interface

• Rankine display (Vicente, 1996)
• Deviations in the shape of the bell curve
  indicate system problems
• The current value of variables can be placed in
  the space defined by the curve, which diagnoses
  system problems
• Vicente found that NPP operator performance
  better with Rankine display that with set of
  single-sensor, single-indicator (conventional
  NPP) displays

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Steam
Liquid
Liquid And Steam
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Single sensor, single indicator
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Cues to Depth

• Dynamic displays
• Display compatibility
• Principal of pictorial realism (static)
• Principal of moving part (dynamic)
• Frequency separated display
• Ecological interface design
• Depth cues and depth in displays

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Perception of Distance

• How do we perceive depth?

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Depth Cues

• Object Centered
• linear perspective
• interposition
• height in the plane
• light and shadow
• relative (familiar) size
• texture
• proximity luminance covariance
• atmospheric perspective
• motion parallax
• structure through motion

• Observer Centered
• binocular disparity
• convergence
• accommodation (monocular)

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How Are Cues Combined?

• Additive cue theory
• Each added cue increases compellingness of depth
• Cue dominance
• Ambiguous display situation
• Winners Interposition, Motion Parallax,
  Binocular Disparity
• Stereo displays expensive and inconvenient

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Depth Cue Effectiveness

• Different Cues Most Effective at Different
  Distances
• At 3000-30,000 feet, Interposition (Occlusion),
  Relative Size, and Texture Density are Most
  Effective
• Binocular Disparity most Effective at Close
  Distances

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Depth Perception and Hypothesis Testing

• When viewing a scene (e.g., view from the
  drivers seat), we make assumptions about the
  distances of objects (based on depth cues)
• Note that most monocular depth cues (e.g.,
  familiar size) are not infallible
• Sometimes these assumptions are incorrect
• Drivers assume average vehicle size
• Smaller cars perceived to be farther away
• Result Small cars are rear ended more frequently

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Runway Slope

• Similar assumptions occur in aviation as well
• Runway approach sloping up leads to hard landing
• Assume youre higher than you actually are
• Descend too quickly...
• Approach sloping down leads to late landing

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Black Hole Illusion

• A black hole exists on dark nights when there are
  no surface lights between the aircraft and the
  runway (over water, desert)

• Landing a long straight-in approach over the
  featureless terrain environment (usually in dark)
  
• Common tendency which pilots must resist is
  landing short of the runway

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Black Hole Research

• Kraft (1978) had pilots perform simulated
  nighttime landing (clear conditions, dark
  terrain)
• When altimeter eliminated from simulator, pilots
  assumed that their altitude was higher than
  actually the case
• When flying a typical approach without reference
  to altimeter, get following curve

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Feels like runway too close going to overshoot
runway Im coming in too fast
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If the pilot keeps the visual angle subtended by
the runway constant, the approach path will be an
arc.
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Black Hole Research

• Many case studies are consistent with Krafts
  results
• After Krafts research was publicized, commercial
  airlines instituted corrective measures
• For example, copilot monitors the altimeter
  during approach and calls out altitudes at
  regular intervals to the pilot
• Krafts contributions Effectively eliminated
  inadvertent visual overestimation of altitude as
  a contributing factor to nighttime landing
  accidents in commercial aviation (Leibowitz,
  1988)

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3D Graphs and Linear Perspective

• Additional bias produced with use of linear
  perspective

• Also Applies to Coded Altitude

Source Battlespace Visualization -- James
Rayson, Mitre Corp.
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3D Graphs and Linear Perspective
Source Bill Wright, Oculus
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FO
CL
NA
NO
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3D Bars in Depth Results

• Error greatest for when bars far apart and there
  was greater variability in bias scores
• Augmented CPM to distinguish between cyclical
  bias commonly observed in proportion judgments
  and bias resulting from improper size-distance
  scaling
• P ? P
• Absolute value of size-distance scaling parameter
  ? was greater when bars far apart

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3D Bars in Depth Conclusions

• Error greatest for when bars far apart and there
  was greater variability in bias scores
• CPM fits showed that this due to size distance
  scaling problem and bar location did not affect
  cyclical bias
• Portray bars at similar depths in 3D bar graphs
  if accurate judgments are necessary or use 2D

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3D Displays of 3D Space

• Not effective to use depth to represent
  non-distance dimension
• In contrast, compelling reasons for using 3D
  display to represent 3D worlds
• CAD workstation
• Computer games
• Contour map studied by petroleum geologist or
  military commander
• Display of air traffic

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3D Displays of 3D Space
General spatial awareness for air traffic 3D
display for 3D picture 2D representation
provides necessary information, but mental effort
required to integrate and reconstruct picture
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Displaying Three-Space

• Conventional cockpit instrumentation separates
  information into specific values
• air speed,
• altimeter,
• directional indicator,
• attitude indicator

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Flight Path Indicator

• Flight Path Indicator provides more integrated
  representation (Wickens et al., 1989)

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2D vs. 3D

• In general evidence indicates that 3D displays
  better for tasks requiring information
  integration from all three dimensions
• e.g., Liu et al. (1997) 3D graphic of human form
  more effective than 2D views when complex
  asymmetric postures were assessed
• e.g., Wickens et al. (1994) 3D scatterplots
  better than separated 2D scatterplots for tasks
  involving assessing the shape of the 3D surface

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PCP Rides Again

• Results consistent with predictions of proximity
  compatibility principle
• When information integrated into three
  dimensions, performance on tasks requiring such
  integration should improve
• However, PCP also implies that
• 3D displays should not be good for focused
  attention tasks involving 1 or 2 of the
  dimensions

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Problems for 3D

• Hollands, Pierce, and Magee (1998) found problems
  for 3D (relative to 2D) display when observers
  estimated distance between two lines

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Problems for Flight Path Indicator (and 3D
Displays)

• Two Problems for 3D Displays of 3D Space
• 1) Focused attention tasks performed poorly
• 3D displays are ambiguous at depicting specific
  distances and depths
• 2) False Hypotheses (Necker Cube) height in
  plane vs. relative size

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Problems for Flight Path Indicator (and 3D
Displays)

• 2) False Hypotheses (Necker Cube)

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General Summary

• Dynamic displays
• Display compatibility
• Principal of pictorial realism (static)
• Principal of moving part (dynamic)
• Frequency separated display
• Ecological interface design
• Depth cues and depth in displays