Division of Information Man-agement Engineering

INFORMATION THEORY1. THE COMMUNICAION SYSTEMS

○ Channel capacity (C) – the amount of info transmitted per time through a channel

Hick-Hyman Law

Division of Information Man-agement Engineering

○ the rate of gain of information (Hick, 1952) and index of performance (IP) in Fitts (1948)

Hick-Hyman Law

Division of Information Man-agement Engineering

2. QUANTIFYING INFORMATION○ Information – reduction in uncertainty (bit)○ Shannon-Weiner measure of information

or ○ Have : the entropy of a stimulus or a set of stimuli when the alterna-

tives are not equiprobable○ Hmax : the alternatives are equiprobable○ HT = H(x) – Hy(x)

where H(x): the expected information of the source Hy(x): the received information at the destination

Hick-Hyman Law

Division of Information Man-agement Engineering

THE HICK-HYMAN LAW1. Hick (1952) Original Experiments

Hick-Hyman Law

choice RT vs. stimulus info content errorless responses

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○ Experiment II○ 3 phases – as fast as possible, then as accurately as possi-

ble, finally as fast as possible again

Hick-Hyman Law

training (ac-curate)

diamonds for fast RT

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2. Hyman (1952) Original Experiments

Hick-Hyman Law

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2. Hyman (1952) Original Experiments○ The first to articulate the linearity between RT and HT

○ Altered the probabilities of the stimuli to assess RT as a function of HT

○ RT was linear as s function of bits of the alternatives with unequal probabilities

○ RT = a + b HT

○ 1/b: the rate of gain of information (information capacity)

Hick-Hyman Law

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4. Research and ApplicationsSpeed-Accuracy TradeoffStimulus-Response Compatibility (SRC)○ Compatible S-R pairs facilitate the responding of a stimulus,

thus yielding a higher rate of information transferPsychometrics○ investigate RT-IQ relationshipHCI Applications

Hick-Hyman Law

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5. FITTS’ LAW○ a linear relationship between task difficulty (ID) and RT

○ human motor system as a communication channel, movement ampli-tude as the signal, target width as the noise

1. Fitts (1954) Original Experiemtns○ the reciprocal tapping task○ Experiment I – metal-tipped stylus (1 oz vs. 1 lb); W from 0.25” to

2”; D from 2 to 16 ”; accuracy was encouraged

Fitts’ Law

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Fitts’ Law

○ IP (index of performance or throughput) = ID/MT the capacity of the human motor system

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○ channel capacity (Shannon’s Theorem 17)

○ W is the bandwidth, P is the signal power and N is the noise power

2. Theoretical Development○ Welford (1960) ○ MacKenzie (1992) ○ Meyer et al. (1988) ○ deterministic iterative-correction model (Crossman and Goodeve,

1983), stochastic optimized-submovement model (Meyer and col-leagues, 1990)

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○ Meyer et al. (1998) where n is number of submovements

3. Research and Applications○ kinematics and neurocognitive focusSpeed-Accuracy TradeoffPsychometricsHCI ApplicationsPointing.Angle of Approach.○ the original Fitts’ paradigm – 1D task

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○ Accot and Zhai (2003) – classical paradigm as AP (pointing with amplitude constraints); paradigm with height constraints as DP (pointing with direction constraints)

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Semantic Pointing.○ both decreasing A and increasing WText Entry on Soft Keyboards.○ text entry on GUINavigation.

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6. INTEGRATION OF THE LAWS○ Combine the Hick-Hyman Law and Fitts’ Law

○ Beggs et al. (1972)○ Fitts’ Law did not hold in the fusion

○ Hoffman and Lim (1997)○ Home-to-target paradigm with both sequential and con-

current tasks○ The sum of the decision and movement time (sequential)○ Substantial interference (concurrent)

○ Soukoreff and MacKenzie (1995)○ Unable to fit the data to the model

Hick-Hyman Law

Division of Information Man-agement Engineering

7. THE HICK-HYMAN LAW AND HCI○ Common characteristics in both Laws

a. Same analogies based on Shannon and Weaver’s (1949)b. Same measures such as performance rate and information ca-

pacityc. Substantial support in research

○ Possible reasons for the lack of momentum in HCI (Laming, 1966)1. discrepancies between Shannon’s theory and Hick’s analogy2. Victim for the eviction of the soft sciences by hard sciences

I. Fitts’ Law has also comparable quantitative componentsII. HCI has shifted its focus to include some soft sciences

such as sociology

Hick-Hyman Law

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1. Difficulty in Application○ No need to engage in the complexity of the information theoretic

measures

2. Complexity of Stimuli○ Multidimensional stimuli for the highly complex interfaces

needed with simple unidimensional stimuli to reduce confound-ing

3. Levels and Types of Performance○ Fitts’ for somewhat monotonous tasks

Hick-Hyman Law