Usability and Information System Design

Prof. Stephen Hirtle

University of Pittsburgh

hirtle@pitt.edu

Outline

What is Usability? How should it apply to Information Systems Design? What resources are available to learn more? Some applications for location-based services and

wayfinding

What is Usability?

The ease to which (information) tools can be used to complete the task at hand.

With interfaces, could use the term user-friendly, but usability applies to all technologies from toasters to highway systems.

Information Design

User Centered Design Software Design

Usability

Interface Design

Information Visualization

Based on the Cognitive Processing

http://en.wikipedia.org/wiki/File:HumanProcessorModel.jpg

Based on the Cognitive Processing

http://en.wikipedia.org/wiki/File:HumanProcessorModel.jpg

Constructivist view

Perception is driven by cognition

Cognition, in turn, is driven by perception

“Old” idea from (Niesser, 1967)

http://huwi.org/2.php

Some examples follow …

Perception is not a direct copy of the environment

http://www-bcs.mit.edu/people/adelson/checkershadow_illusion.html

Move B to show effect

http://www.sandlotscience.com

http://www.blogt.nl/images/juli2003/raareffect.jpg

Ambiguous figures

Can even see in photos…

Marbled Teal, an endangered species in Europe (sent from David Mark, 2001)

The Joy of Visual Perception: A Web Book - Peter K.Kaiser Phi Phenomenon

http://www.yorku.ca/eye/funthing.htm

Pinker on Illusions, NY Times, 1/13/2008 “Illusions are a favorite tool of perception scientists for

exposing the workings of the five senses, and of philosophers for shaking people out of the naïve belief that our minds give us a transparent window onto the world (since if our eyes can be fooled by an illusion, why should we trust them at other times?).”

Magic , Perception and Cognition

Macknik SL, King M, Randi J, Robbins A, Teller , Thompson J, Martinez-Conde S (2008). Attention and awareness in stage magic: turning tricks into research. Nature Reviews Neuroscience; 9, 871-879.

Magic and the brain Susana Martinez-Conde and Stephen L. Macknik (2008) Scientific American, vol 299(6) pp 72-79, December 2008

“Magicians have been testing and exploiting the limits of cognition and attention for hundreds of years. Neuroscientists are just beginning to catch up”

New York Times, Feb 12, 2007

Giuseppe Arcimboldo

http://cvcl.mit.edu/hybrid_gallery/gallery.html

Eye movements play an important role Yarbus, 1967

An Enigma: Change Blindness

Compare

Open folder here

Change Blindness: Ron Rensink

One of our latest projects has explored the question of why people often do not see things that are right in front of their eyes. (This form of "blindness" is a major cause of traffic accidents.) To study why this happens, we developed a "flicker" paradigm in which two images - an original and a modified one - are sequentially alternated, with a brief (<100 ms) flash placed between the images. Under these conditions subjects have a very difficult time seeing the change between the two pictures,even when the changes are large, and the subjects are expecting them. Evidently, attention is required to see change; without it, people will look at but not see the change.

http://www.psych.ubc.ca/~rensink/

Change Blindness

Not central to scene – almost to 11 seconds to notice Central to scene – 4.5 seconds No interruption – 1 second

Change Blindness

Implications of the research Our representations of the visual world are very sparse.

“Our impression of a world that is both coherent and detailed is therefore based only on the properties of the world itself, and not on the properties of the representations that underlie our visual experience.”

Note: You don’t even need to include a blank space if you add other masking noise

An Enigma: Change Blindness

Compare

Change blindness

Something changed in the previous picture. If you weren’t able to see the change, compare with the

version that does not have the mudsplashes

From J.K. O'Regan Laboratoire de Psychologie Expérimentale, CNRS, Paris; R.A. Rensink Nissan Cambridge Basic Research & J.J. Clark Electrical Engineering Department, McGill University

One more example using continuous video Start movie

See the Colour-changing Card Trick at http://www.quirkology.com/USA/Video_ColourChangingTrick.shtml

Or even Wizard of Oz http://www.youtube.com/watch?v=XICas3_ynEw Watch :38 to 1:32 (can mute sound) See next slide for example

More examples

Cognitive Daily http://scienceblogs.com/cognitivedaily/2007/09/why_we_

are_blind_to_some_chang.php

Rensink’s lab http://www.psych.ubc.ca/~viscoglab/demos.htm

Change Detection Database http://viscog.beckman.uiuc.edu/change/

On to theory …

Jnd.org

Argues for design principles and then applies them to interface design

In his essay: Design as Communication, Norman revisits his

theory of user-centered

design

Builds on the notion of affordances

Applies to information systems to doorknobs

http://www.baddesigns.com

Click to enlarge

Builds on the notion of affordances

Applies to information systems to doorknobs

http://www.baddesigns.com

Affordances and Design – Don Normanhttp://www.jnd.org/dn.mss/affordances_and.html

In the world of design, the term "affordance" has taken on a life far beyond the original meaning. It might help if we return to the original definition.Let me try to clarify the definition of the term and its many uses.

I introduced the term affordance to design in my book, "The Psychology of Everyday Things" (POET: also published as "The Design of ..."). Theconcept has caught on, but not always with true understanding. Part of the blame lies with me: I should have used the term "perceived affordance,"for in design, we care much more about what the user perceives than what is actually true.

… because I can click anytime I want, it is wrong to argue whether a graphical object on the screen "affords clicking." It does. The real question is about the perceived affordance: Does the user perceive that clicking on that location is a meaningful, useful action to perform?

© 2008 R Allen

Affordances with MS PPT 2007??

Nudge?

© 2008 R Allen

Design as Communicationhttp://www.jnd.org/dn.mss/design_as_comun.html

I was traveling, and once again I woke up to a strange hotel room in a strange city: Delft, The Netherlands in this instance. I went to take a shower to prepare myself for my 8:30 AM pickup. As I looked over the bathtub and shower, wondering where to put the soap, I realized that the design was talking to me. "Put the soap here," the metal dish on the side practically screamed at me. …

Later, as I thought back about that morning shower, I realized I had been communicating with the designers. "Grab here," the bar was telling me. "Put the soap on me," the wire rack soap dish screamed. "Here are your towels," said the horizontal bars at the rear wall, at the end of the tub, conveniently stocked with towels.

baddesigns.com

Click on image for website

Road sign often leads to confusions

http://www.signslanguage.com

baddesigns.com

CONCEPTUAL MODELS & USER-CENTERED DESIGN – Donald Norman Years ago, I championed "User-Centered System

Design," based upon the point that designers had to focus their attention upon the users of their systems. I diagrammed the interaction between designer and user as a triad:

The designer's model, the system image, and the user's model. For people to use a product successfully, they must have the same mental model (the user's model) as that of the designer (the designer's model). But the designer only talks to the user via the product itself, so the entire communication must take place through the "system image": the information conveyed by the physical product itself.

I have long maintained that the appropriate way to design a complex system is to develop a clear, coherent conceptual model (ideally the same as the designer's conceptual model) and to design the system so that the user's mental model would coincide. I had always assumed this would be done through the design of the "System Image": the artifact plus any auxiliary material, such as manuals and help systems.

DeSousa makes a major advance in our understanding of the communication model. If the designer explains the reasoning behind the model, the user will find the task of uncovering the conceptual model much easier. In other words, what we need to provide to people is reasons, not just methods.

Systems usually try to convey the actions that need to be taken at any point in a sequence. A major driving force in the development of graphical user interfaces -- the GUI -- was to make all possible commands visible, so at any point a person could discover what to do simply by looking through the set of possibilities.

The technique of "graying out" menu items that are not applicable at the moment is a communicative tool: indicating the existence of the command while simultaneously indicating that in this situation, it does not apply.

Although GUIs were a major step forward, they simply providing information about the set of possibilities, not about the reasoning. Thus, if a grayed-out command appears to be precisely what the person is searching for, the system simply communicates its non-availability: it does not suggest why it is not available, nor how to change it to be available.

Human beings are explanation machines. We are always trying to understand the world around us, and we make up stories to explain the occurrences we experience. If there is sufficient evidence or knowledge, these stories are reasonably accurate, but in the absence of such information, the story -- in other words, the explanation -- is apt to be wrong.

In many cases, the person simply cannot construct an adequate explanation, not even for themselves, which means they remain puzzled and are apt to have the same difficulty every time they encounter the situation.

Additional jnd.org essays

The truth about Google's so-called "simplicity" The truth? It isn't simple. Why does it look simple?

Because you can only do one thing from their home page: search. If you want to do one of the many other things Google is able to do, oops, first you have to figure out how to find it, then you have to figure out which of the many offerings to use, then you have to figure out how to use it. And because all those other things are not on the home page but, instead, are hidden away in various mysterious places, extra clicks and operations are required for even simple tasks -- if you can remember how to get to them.

The tools …

© 2007

Selective Attention

• Selective attention seems to involve adding more cognitive resources for processing sensations and it is guided by higher level cognitive processes.

• Attention may be compared to a spotlight with some objects highlighted compared to others.

• People often attend more to items and events which reinforce their expectations.

55

Can measure where you attend by examining eye movements Yarbus, 1967

F-Shaped Pattern For Reading Web Content

http://www.useit.com/alertbox/reading_pattern.html

© 2007

Interface Engineering

• Can we set the parameters of an interface the same way that an engineer follows equations when building a bridge?

• One example is the Keystroke Level Model. This tries to predict the time to complete specific commands with keystrokes and mental planning time.

• Works well for simple tasks, but not for complex ones.

Keystroke analysis

© 2008 R Allen

Motor times vary with motor task

K - Keystroke (.12 - 1.2 sec; .28 recommended for most users). T(n) - Type a sequence of n characters on a keyboard (n ´ K sec). P - Point with mouse to a target on the display (1.1 sec). B - Press or release mouse button (.1 sec). BB - Click mouse button (.2 sec). H - Home hands to keyboard or mouse (.4 sec). M - Mental act of routine thinking or perception (.6 - 1.35 sec; use

1.2 sec). W(t) - Waiting for the system to respond (time t must be

determined).

Using the Keystroke-Level Model to Estimate Execution Times David Kieras, University of Michigan

© 2008 R Allen

Analysis of the Utility of Office Applications - Interim Status ReportHelsinki University of TechnologyMat-2.177: Seminar on case studies in operations research

Benefits of GOMS (Goals, Operators,

Methods, and Selection Rules) Gray, W. D., John, B. E., & Atwood, M. E. (1993). Project Ernestine:

Validating a GOMS analysis for predicting and explaining real-world performance. Human-Computer Interaction, 8(3), 237-309.

Project Ernestine served a pragmatic as well as a scientific goal: to compare the worktimes of telephone company toll and assistance operators on two different workstations, and to validate a GOMS analysis for predicting and explaining real-world performance.

Darker line indicates critical path

Proposed workstation added 3 motor and one cognitive cell to this path

Benefits of GOMS (Goals, Operators,

Methods, and Selection Rules) Gray, W. D., John, B. E., & Atwood, M. E. (1993). Project Ernestine:

Validating a GOMS analysis for predicting and explaining real-world performance. Human-Computer Interaction, 8(3), 237-309.

Contrary to expectations, GOMS predicted and the data confirmed, that performance with the proposed workstation was slower than with the current one. Pragmatically, this increase in performance time translates into a cost of almost $2 million dollars a year to NYNEX. Scientifically, the GOMS models predicted performance with exceptional accuracy.

Have I reached the party to whom I am speaking?

Sometimes the solution to usability problems is non-intuitive Consider the problem of understanding road signs in

terms of perception, cognition, information extraction, and decision

© 2008 R Allen

Road Signs near Montefollonico, Tuscany, Italy

http://www.edinphoto.org.uk/0_MY_P_I/0_my_photographs_italy_-_tuscany_road_signs_1nq21_largest.htm

Remove road signs and increase safety!

Huh? What are you talking about?

Well, Bohmte, a town in Germany is doing just that. They are removing all street signs in an effort to improve traffic safety. The concept is that road users will now have to negotiate their behavior with each other, rather than have it prescribed by rules. The idea being that people will pay more attention to what other road users are doing and hence cause fewer accidents.

Guess what, it works! The idea first started in the  Dutch town of Drachten, and since they implemented this, accidents are way down.

http://blogs.edmunds.com/Straightline/3428

Read more about this social experiment and how it applies to information design in Zittrain’s Future of the Internet and How to Stop It.

http://www.magdeburgerjoe.com/2009/09/no-more-traffic-lights.htmlhttp://www.cbsnews.com/video/watch/?id=5290564n&tag=contentMain;contentBody

© 2007

Evaluation ofInterfaces/Interaction

• Three main approaches– Usability testing

• Either experiments or discount usability• Highly replicable but not necessarily realistic

– Field studies• Watching users in natural environments• High generality

– Heuristic evaluation• Apply simple checklists or • Relatively easy and cheap to conduct

Summary

Need to consider the entire cognitive processing model

Affordances and conceptual models

Tools Eye movements Keystroke analysis and GOMS

Consider nontraditional solutions

On to Part II …

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