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540-310 Human Factors in Information Seeking and Use

Wooseob Jeong

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Notice

Class web site http://www.sois.uwm.edu/jeong/540310

IM communicationFirst assignment is due on February 18th before the class. Review of Norman (1993) Submission should be done via email. Strength, Weakness, Application,

Suggestion

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Eight Golden Rules of Interface Design (0)

Shneiderman (1998)

Examples of Violation Interface Hall of Shame http://digilander.libero.it/chiediloapipp

o/Engineering/iarchitect/

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Eight Golden Rules of Interface Design (1)

Strive for consistency This rule is the most frequently violated

one, but following it can be tricky because there are many forms of consistency. Consistent sequences of actions should be required in similar situations; identical terminology should be used in prompts, menus, and help screens.

Exceptions, such as no echoing of passwords or confirmation of the delete command, should be comprehensible and limited in numbers.

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Eight Golden Rules of Interface Design (2)

Enable frequent users to use shortcuts As the frequency of use increases, so

do the user’s desires to reduce the number of interactions and to increase the pace of interaction. Abbreviations, special keys, hidden commands, and macro facilities are appreciated by frequent knowledgeable users.

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Eight Golden Rules of Interface Design (3)

Offer informative feedback For every user action, there should be

system feedback. For frequent and minor actions, the response can be modest, whereas for infrequent and major actions, the response should be more substantial.

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Eight Golden Rules of Interface Design (4)

Design dialogs to yield closure Sequences of actions should be organized

into groups with a beginning, middle, and end. The informative feedback at the completion of a group of actions gives operators the satisfaction of accomplishment, a sense of relief, the signal to drop contingency plans and options from their minds, and an indication that the ways is clear to prepare for the next group of actions.

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Eight Golden Rules of Interface Design (5)

Offer error prevention and simple error handling As much as possible, design the system

such that users cannot make a serious error; for example, prefer menu selection to form filling and do not allow alphabetic characters in numeric entry fields. If users make an error, the system should detect the error and offer simple, constructive, and specific instructions for recovery.

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Eight Golden Rules of Interface Design (6)

Permit easy reversal of actions As much as possible, actions should

be reversible. The feature relieves anxiety, since the user knows that errors can be undone, thus encouraging exploration of unfamiliar options.

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Eight Golden Rules of Interface Design (7)

Support internal locus of control Experienced operators strongly desire

the sense that they are in charge of the system and that the system responds to their actions. Surprising system actions, tedious sequences of data entries, inability or difficulty in obtaining necessary information, and inability to produce the action desired all build anxiety and dissatisfaction.

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Eight Golden Rules of Interface Design (8)

Reduce short-term memory load The limitation of human information

processing to short-term memory (7± 2) requires that displays be kept simple, multiple page displays be consolidated, window-motion frequency be reduced, and sufficient training time be allotted for codes, mnemonics, and sequences of actions.

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Direct Manipulation

Command line system UNIX, 80’s PC

GUI Iconomized commands Icon: representation, meaning Object-Action Interface (OAI) model

Virtual Reality

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Task-related Organization

Menu system How can you organize menus? How can you display menus? Multiple ways for a menu item

Form Filling Coded fields (mask) Listbox, checkbox, radio buttons …

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Command Language vs. Natural

Language

grep –v ^$ file_a > file_b Not obvious Delete blank lines from file_a and

save the result in file_b

Delete vs. rm

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Response Time (1)

How long are you willing to wait to load a web page? At most, 2 seconds! Implications: few graphics, Java,

Flash, … Trade-off: not so exciting Design vs. Contents

Productivity affected

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Response Time (2)

Appropriate Response Time Typing, cursor motion, mouse

selection: 50-150 milliseconds Simple frequent tasks: 1 second Common tasks: 2-4 seconds Complex tasks: 8-12 seconds

Users should be advised of long delays Alternatives: elevator mirror, blinking

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Response-time (3)

User prefer shorter response timesLonger response times (>15 secs) are disruptiveUsers change usage profile with response timeShorter response time leads to shorter user think timeA faster pace may increase productivity, but many increase error ratesError recovery ease and time influence optimal response time

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Humans Generally Better (1)

Sense low level stimuliDetect stimuli in noisy backgroundRecognize constant patterns in varying situationsSense unusual and unexpected eventsRemember principles and strategiesRetrieve pertinent details without a priori connectionDraw on experience and adapt decisions to situationSelect alternatives if original approach fails

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Humans Generally Better (2)

Reason inductively; generalize from observationsAct in unanticipated emergencies and novel situationsApply principles to solve varied problemsMake subjective evaluationsDevelop new solutionsConcentrate on important tasks when overload occursAdapt physical response to changes in situation

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Machines Generally Better (1)

Sense stimuli outside human’s rangeCount or measure physical quantitiesStore quantities of coded information accuratelyMonitor pre-specified events, especially infrequent onesMake rapid and consistent responses to input signalsRecall quantities of detailed information accuratelyProcess quantitative data in pre-specified ways

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Machines Generally Better (2)

Reason deductively: infer from a general principlePerform repetitive pre-programmed actions reliablyExert great, highly-controlled physical force.Perform several activities simultaneouslyMaintain operations under heavy information loadMaintain performance over extended periods of time

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The Human Mind (1)

Complex, but powerful!Stories – not logicalTo err is human! Slip vs. mistakes

Tunnel Vision Functional fixedness, cognitive

narrowing

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The Human Mind (2)

People do err, especially when required to do things for which we are not suited. The trick is designing technology is to provide situations that minimize error, that minimize the impact of error, and that maximize the chance of discovering error once it has been committed. The human-centered way.

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Interface Hall of Shame

http://digilander.libero.it/chiediloapippo/Engineering/iarchitect/Obviously, there is Interface Hall of Fame page. http://digilander.libero.it/chiediloapippo/Engi

neering/iarchitect/mfame.htm

Think about this: “Show friendly HTTP error messages” Ex) ASP error message – http://

www.sois.uwm.edu/jeong/asp.asp

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Distributed Cognition

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Three Mile Island Accident

http://www.libraries.psu.edu/crsweb/tmi/tmi.htmThe main control console signals overwhelmed human operators. 18 of 22 problems identified were human factors problemsVideo!

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A place for everything, and everything in its place

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A Technological Breakthrough

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Other Technology Needed!

Copy Machine – coping toolsStandardized Paper Size Is it solved really?

Post-It Notes

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Organization of Things

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Organization of Knowledge

Hardware Store Hierarchical and organized by function Coupled by expertise

Dictionary/Encyclopedia Alphabetical – problems? Advantage of digital format

Organization of Web? Similar to Library Catalog? Search engines