Controls & Design Flashcards

1
Q

What are controls?

A

Controls are the action after a decision is made

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1
Q

What is the speed of action selection influenced by?

A

the number of
possible alternative actions that could be
selected.

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2
Q

What is the Hick Hyman Law of reaction time?

A

A logarithmic increase in reaction time (RT) as
the number of possible stimulus response
alternatives (N) increases.

RT = a +
b Log2 N

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3
Q

What is the formula to predict response time?

A

Reaction Time = a + bH

More uncertainty, more time

a = simple reaction time (just to respond)
b = additional time for every 1 bit increase in
information

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4
Q

What is the most efficient way to deliver a given amount of information?

A

give a smaller
number of complex decisions rather than a
large number of simple decisions.

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5
Q

What is Response
expectancy?

A

We perceive rapidly and accurately that
information that we expect.

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6
Q

What are the principles of response selection?

A
  1. Decision
    complexity
  2. Response
    expectancy
  3. Compatibility
  4. Feedback
    5.Speed accuracy trade off
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7
Q

What is Location compatibility?

A

Mapping

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8
Q

What is movement compatibility?

A

moving a lever right
should move the display to the right

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9
Q

What are factors affecting reaction time?

A
  • Age
  • Intoxication
  • Time of day (especially in auditory response)
  • Fatigue
  • Practice
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10
Q

What is an example of a Positioning Control Device?

A

Mouse with a cursor to a target

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11
Q

What affects the movement time of positioning control devices?

A

movement of the hand or fingers to
the control device
movement of the control device in
some direction.

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12
Q

What is the equation for Fitt’s Law?

A
  • *MT =**
  • *a + b log 2 (2A/W)**

MT is movement time
A is the distance (or amplitude) of movement from start to
target center
W is the width of the target, which corresponds to “accuracy”
(2A/W) is the index of difficulty

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13
Q

What is the ID of Fitt’s law?

A

Index of difficulty

log 2 (2A/W)

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14
Q

What are some implications of Fitt’s law

A

•Big targets at a close distance are acquired faster than small
targets at long range
•ID provides a single combined measure of two main physical
properties of movement tasks
•ID increases by one unit for each doubling of amplitude and
halving of width
•Positive intercept indicates additive factors unrelated to ID. It
can be related to mechanism of movement and/or selection
(mouse, button,etc)

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15
Q

What is Welford’s ID?

A

MT =
a + b log <u>2</u> (A/W + 0.5)

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16
Q

How is Welford’s law different than Fitt’s law?

A
  • MT is proportional to the index of difficulty
  • Better fit to data than Fitts ’ original
  • Possible negative ID
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17
Q

What is Shannon’s ID?

A

MT =
a + b log <u>2</u> (A/W + 1)

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18
Q

How is Shannon’s Law different from Fitt’s law?

A
  • MT is proportional to the index of difficulty
  • Best fit to data
  • Positive ID
  • Follows from Info Theory
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19
Q

What are 3 device characteristics?

A
  • Direct position controls
  • Indirect position controls
  • Indirect velocity controls
20
Q

What is an example of a direct position control?

A

Light pen and
touch screen using
a stylus or finger
on a tablet.

21
Q

What is an example of an indirect position control?

A

Mouse, touch pad,
and touch tablet.

  • (Changes in the*
  • position of the limb*
  • directly correspond to*
  • changes in the*
  • position of the cursor,*
  • but on a different*
  • surface.)*
22
Q

What is an example of an indirect velocity control?

A

Joystick and cursor keys.

23
Q

What are the 3 types of joysticks?

A
  • Isotonic
  • Isometric
  • Spring loaded
24
What is an isotonic joystick?
•Typically, cursor moves as a result of movement of the joystick handle. •Handle does not move back to a neutral position.
25
What is an Isometric Joystick?
•Cursor moves as a result of the force applied to the joystick handle. •Joystick does not move at all. (In some keyboards it's the weird dot thing)
26
What is a spring-loaded joystick?
•Resistance is proportional to the force applied. •Displaced, but returns to a neutral position. •Offers proprioceptive and kinesthetic feedback.
27
What are the two important characteristics of usability?
Feedback and gain
28
What is gain in usability?
Gain is defined as the change of cursor position/change of control position.
29
What is control movement?
positional input to control
30
What is Controlled element?
aspect of system ultimately affected by control movements
31
What is the target?
displayed parameter to be matched
32
What is Forcing function?
disturbances to target sidenotes: in UX: **forcing** functions create barriers to divert people away from danger and towards desired outcomes
33
What is pursuit tracking?
See both controlled element & target
34
What is compensatory tracking?
Only error (difference desired/actual) Target & control movements confounded
35
How does pointing differ from tracking?
In pointing: Stationary target No lag Gain is only control system parameter
36
What does Control Order mean?
What the control controls.
37
What does it mean if a control is zero-order?
the cursor controls the position of the target
38
What does it mean if a control is first-order?
order means it controls the velocity of the target.
39
What does it mean if a control is second-order?
a change in the position of the cursor changes the acceleration of the target.
40
What is instability in controls?
caused by lag somewhere in the total control loop
41
What are Open loop controls?
no feedback used by experienced operators
42
What are closed loop controls?
feedback is valuable in learning or fine tuning a mental model.
43
What is response expectancy?
We perceive rapidly and accurately the information that we expect.
44
What is decision complexity?
The speed with which an action can be selected is strongly influenced by the number of possible alternative actions that could be selected.
45
What is the Hick Hyman Law of reaction time?
RT = a + b Log2 N logarithmic increase in reaction time (RT) as the number of possible stimulus response alternatives (N) increases.
46
What are direct position controls?
Light pen and touch screen
47
What are Indirect position controls?
Mouse, touch pad, and touch tablet.
48
What are indirect velocity controls?
Joystick and cursor keys