Kevin Hale
December 05, 2011
22k

# 5 Interface Laws Every Software Designer Should Know

Y Combinator's Kevin Hale teaches the 5 laws every software designer should know about interface design. He'll walk you through the experiments used to discover them and visualize the math in ways that makes it easy to see how to apply them in your day to day design work.

## Kevin Hale

December 05, 2011

## Transcript

Kevin Hale

5. ### Fitts’s Law T = a + b log (1+ D/W)

2 How humans point at things.

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9. ### Shannon-Hartley Theorem C = B log (1+ S/N) 2 T

= a + b log (1+ D/W) 2

12. ### Fitts’s Law T = a + b log (1+ D/W)

2 Distance Width Time
13. ### Linear vs Log 0.0 1.5 3.0 4.5 6.0 0 2

4 6 8 10 12 14 16 18 20 22 24 26 28 30 Linear vs Log

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23. ### Fitts’s Law T = a + b log (1+ D/W)

2 Distance Width Time

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Width Time

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44. ### Steering Law / Accot-Zhai Law Length ∫ T = a

+ b C ds W(s) How humans move in a tunnel.

48. ### Steering Law / Accot-Zhai Law Constant Constant Length Width ∫

T = a + b C ds W(s) Path Time
49. ### Steering Law / Accot-Zhai Law Width of Tunnel ds W(s)

Instantaneous Speed dT = b

53. ### Nested Menu Optimizations A B C D 1 2 3

4 i ii iii iv

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2
61. ### Hick’s Law T = b · log (n + 1)

2 It takes less time to identify an object from fewer things.
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2
66. ### Hick’s Law T = b · log (n + 1)

2 Constant Binary Search Decisions Uncertainty Time
67. ### Hick’s Law # of Choices 1 2 3 7 15

Relative Time 1 1.6 2 3 4
68. ### Hick’s Law T = b · log (n + 1)

2 Binary Search Decisions Time
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Chicken Bear

Chicken Bear
77. ### Find the monkey. Humans Animals Robots Monsters Cat Dog Monkey

Chicken Bear x

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88. ### 1970’s Model of Working Memory Visio-Spatial Sketchpad Phonological Loop Central

Executive Long Term Memory

92. ### Colors Digits Letters Shapes Words Random Forms Nonsense Syllables Processing

Time Reciprocal of Memory Span (item ) -1

bbc ibm irs
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109. ### Power Law of Practice RT = aP + c -b

Constant Trial # Constant Constant Completion Time
110. ### Power Law of Practice T = T n -0.4 n00b

Time Trial # Constant Completion  Time n 1
111. ### Power Exponential Law of Practice RT = ae + c

-b(P-1) Trial # Completion Time

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