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Efficiency, Design and Efficient Design

Talk at HCI Seminar

Philip Pavlik

on 11 August 2016

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Transcript of Efficiency, Design and Efficient Design

Efficiency, Design, and Efficient Design Dr. Philip I. Pavlik Jr
Carnegie Mellon University
Human Computer Interaction Institute
16th of September 2010 Bachelors in Economics at University of Michigan

Optimality FaCT (Fact And Concept Training) System My Background First had to build a model (Pavlik & Anderson, 2005) to predict benefits of spaced practice
Japanese paired-associates experiment (Romaji) 4x3x2 design (practices, spacing intervals, retention intervals) Chinese Spacing Effect Test and Study Effects Microeconomics
Game Theory

ACT-R Memory models
Key revelation!
Cognitive models can be be optimized to discover how to optimize the systems they describe Optimizing Needed to better understand the difference between test and study practice
Better undestand the effect of review as a function of time
Compute optimium study duration Application in Lab 180 word pairs
Japanese-> English
3 one-hour learning sessions
testing session (2 cycles through set) after 1 week
2 Control conditions Postdoctoral work at PSLC (Pittsburgh Science of Learning Center)
Funded as research by local philanthropist
Developed ideas from graduate work Flexible System Sequence of Chinese Classroom Experiments
Build an understanding of the classroom use of these systems
Difficult to produce clear long-term learning benefits in classroom
Vastly different ways students use the tutor (much more prior knowledge)
One primary problem with long-term testing (particulary with my motivated population) is with compensatory equalization PhD in Cognitive Psychology at CMU with John Anderson
Jozsef Toth, post doc
Hao Cen, doctoral student
Nora Presson, doctoral student

Eric Emerson
Thomas Bolster
Arthur Tu
Suhrob Munavarov

Ken Koedinger
Brian MacWhinney
John Anderson

Programmers Student Research Assistants Part-time student programmers Executive Guidance Team Genc Doko
Lili Wu
Giancarlo Dozzi

Sushanth Tiruvaipati
James Leszczenski

Jordan Bartlow
Dave Hora
Chris Broglie Part-time Programmers Postdoc and Grad Students Fundementals of Temporal Allocation Utility function
e.g. information transmitted
utility function may be immediate or future utility
Cost function
e.g. time spent
may include monetary or other costs Properties of Cost and Utility Functions Utility function
only starts accumulating after some fixed cost that represents attention switching (perceptual motor cost)
has a decreasing rate of gain (diminishing marginal returns)
Cost function
has a fixed cost component (perceptual motor cost)
increases linearly with time Rate of utility gain (efficiency) is gain/cost
Just like a wage rate
Because of the fixed cost, the initial efficiency is low
Rapid early accumulation of utility overcomes relatively more gradual accumulation of total costs
At some point, accumulation of cost becomes proportionally faster than accumulation of utility
At this transition point, gain per second is greatest HCI Application -- Popup menus 2 basic kinds of popups:
Need to know and merely informative
Informative popups can be optimized with this method

Procedure to Optimize
Record popup frequency and duration in application with popups
Inform users to click on popups as soon as they are read
Plot utility function as cdf of clicks
Compute fixed costs, which are estimated based on cost of minimum of the click time distribution
Compute efficiciency function which utility/cost
Popups optimized Results in Lab are Difficult to Replicate in Classrooms Some students do use much more than required
Possibly other study by poor-users
Possible that transfer is weak to other tasks (e.g. character writing) that are more difficult than the flashcards

These concerns beg the question of how the application is being experienced by users (Forlizzi 2000, 2004)

Classroom must be different than in the lab! Psychological Theory of Experience Based on Barsalou's hypothesis that representation over time (perceived experience) is a whole brain activity

So, roughly, parietal areas organize, temporal areas represent objects, frontal areas act and judge

In this whole representation I have identified 9 factors
like brain areas, somewhat overlapping
like brain areas, they are related (e.g. frontal areas interpret objects that are understood temporally, and organized in a context in the parietal lobe)

Together these 9 factors create a design taxonomy specifically targeted at a "full" representation Facts
Temporal Organization
Spatial Organization
Social Motivation Design Taxonomy Efficient Design Design Problem-Space Assumptions to Optimize

Fixed costs in some areas are neded before any utility obtained
Costs for each factor are independent and additive
Gain for each factor has some theoretical maximum
Gains are mutliplicative since failure in any one design area may influence entire project
Efficiency Function: Conclusion Efficiency isn't just about money Cut from a spreadsheet Gary Becker got the Nobel Prize in Economics in 1992 for related work "A Theory of the Allocation of Time" To see again search for efficient design
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