Models of Performance and Behavior

Patty SakunkooCS 376

May 21, 2009

Patty SakunkooStanford University

• Information Foraging Theory: Framework and Method; Peter Pirolli, in Information Foraging Theory: Adaptive Interaction with Information, Oxford University Press, 2007, pp. 3-29.

• A Morphological Analysis of the Design Space of Input Devices; Stuart K. Card, Jock D. Mackinlay, and George G. Robertson, ACM Transactions on Information Systems, Volume 9, Issue 2, 1992, pp. 99-122.

Conventional HCI Tasks(e.g. programming, math computation)

Information-Intensive Tasks

Well-defined possible goals, potential actions

Uncertain, Probabilistic

Conventional Cognitive Models

Information Foraging Theory (optimization-based approach; including environment)

Design of technologies/UI for Human-Computer-Interaction

Design of technologies/UI for Human-Information Interaction

Information Foraging Theory

Information Overload, Scanty Attention

• To maximize the rate of information gain.

• Patches of Information (e.g. websites) • Basic Problem: Should I continue in the current patch or look for another patch?

• Whether what is expected to be gained from continued foraging in the current patch will be worth the timeHow long to continue searching for information in that patch

How much time to spend on a patch?• Analogous to food foraging • Diminishing Returns Curve- Diminishing returns curve is natural- 80% of users don’t scan past the 3rd page of search results -Charnov’s Marginal Value Theorem

R* = steepest slope from origin = tangent from originIf tb is low, then people tend to switch more easily. (web snacking)

• How well does this model describe your website switching behavior? Exceptions? “strong similarity” “clear connection” “accurate”

• Limitation of analogy? website~patch, info~food

Different kinds of information? Article search, gadget purchase, health

• What does the theory imply about where users switch to in reality? Highly different, highly similar patches, or randomly?

Food - Depletable resource. Depletion in one patch does not affect other patches.- Animals are almost always likely to make decisions based on information scent, humans might not. (Juho) - Prey in wildlife try to avoid foragers.

Information

- Non-exhaustible resource, but redundancy and diminishing returns affect across patches, especially given that many info patches have high overlap (e.g.Travelocity, Expedia, Orbitz)- Information needs a strategy to draw attention and attract foragers.

“Mankind hungers for information in order to gather it as a means for adapting to the world.”

Does there really need to be a functionalist reason for why we are curious about states of the world?

A hint of functionalist/teleological explanation? (information hunger exists for its beneficial adaptive consequence)“Can it really be claimed that we collect information for purposes of survival? I think that humans in the present day have an almost innate desire for information.” – Filip“Unfortunately, I have not seen this trend apply to information foraging.” - Henry

Do “systems tend to evolve in ways that deliver more expected value of information for the cost of interaction”? Any concrete examples of web site design that conforms to this prediction? Any Exceptions?

Claims

“People tend to arrange their environments to optimize their rate of gain. People prefer and select technology design that improve returns on information foraging.”

“it is assumed that users are optimizing their performance in achieving their goals.” (p.18)

• Rational Choice Assumption. Too rational? Goal-oriented? People are quite irrational and often don’t see big pictures of what they’re doing (e.g. diminishing returns), sometimes not even boundedly rational – addiction, etc. (BDT in Psychology).

• Any other incentives/ behavioral rules?Instrumental vs. Non-instrumental Info

Random behaviors/Crossovers. Aesthetics? Sloppy organizer (e.g. our desktop)? Exploratory tasks? Emotion and hedonic experience? Social aspects? Could we consume information for pleasure? For self assurance? To learn more about our goals (hence adaptive goals like searching for where to vacation)?

http://www.musicovery.com/http://www.youtube.com/watch?v=GZUaXDm4qik

Increasing the rate of gain of valuable information always increases fitness (ability to predict and control the environment in order to solve the problems)?

Burt’s Brokerage, Granovetter’s weak ties = information advantageHowever, social distance (outcast), identity, habituation could be a concern. For example, users also seek social belongingness.

“We expect to see a shift in studies from HCI to HII” (Pirolli 2007): Is HII broader or narrower than (or a subset of) HCI?

Formal Models of Behaviors Formal Models vs. Empirical Methods such as ethnography,

multivariable models I find the paper robust in that …. and it is supported by mathematical

foundations. – Juho Kim I'm not that excited about "models" of how people behave. It just

seems that so much more is to be gained by looking at the differences in individuals along with the trends among populations, rather than just describing people's actions as minimizing energy while maximizing benefit. - Jesse Cirimele

“this paper was enough to get you interested, but lost me in the abstraction without ever really reaching the pragmatic.” - Eyal

Pirolli states that frameworks "are typically not testable in and of themselves." I disagree with Pirolli that frameworks are untestable. – Stephen Hess

“If the forager cannot estimate these values (tb) before undertaking a task, the model can only describe search efficiency after-the-fact, rather than prescribe how best to perform it beforehand.” - David

Positives

“extremely important” “accurate” “novel” “insightful” “surprising”

Application to web designs today: Google, Twitter, Social Foraging (Digg)

stanford hci group / cs376

http://cs376.stanford.edu

A Morphological Analysis of the Design Space of Input Devices

Patty Sakunkoo

Main Points Design for HMI: Design an artificial

language to communicate between H and M This paper H -> M Mackinlay M -> H

Morphological design space analysis. Generating the design space

Comprehend different input device designs as points in a parametrically described design space

Testing the designs.

Generating Design Space Primitive Movement Vocabulary

<M,In,S,R,Out,W>

Generating Design Space Composition Operators <Merge, Layout,

Connect>

Taxonomy

Testing the devices Expressiveness

conveys exactly and only the intended meaning

Effectiveness – how well this can be done Footprint – the amount of area consumed Bandwidth – speed of use is a joint product of

the human, the application, and the device.

self-explained?

Predictions Fingers = high bandwidth : could beat the

mouse.

Multi-touch

The pinch

Integration of Design Space Generating and Testing

Is the relationship between positions in the structured design space and their consequences (e.g. footprint, bandwidth, etc.) clear?

Perhaps, test metrics should have more integration with the design space. Like a 3-D space, the 3rd D being a performance metric.

User-based design space?

stanford hci group / cs376

http://cs376.stanford.edu

Thank you.