Instructor: Vincent Duffy, Ph.D.Instructor: Vincent Duffy, Ph.D.

Associate Professor of IEAssociate Professor of IE

Lecture 8 – Human-Computer Interaction Lecture 8 – Human-Computer Interaction

Thurs. Feb. 8, 2007Thurs. Feb. 8, 2007

IE 486 Work Analysis & Design IIIE 486 Work Analysis & Design II

IE 486 Lecture 8 - QOTDIE 486 Lecture 8 - QOTD

Q1. What is a GOMS model? What is the Q1. What is a GOMS model? What is the purpose of a GOMS analysis?purpose of a GOMS analysis?Q2. The case study illustrates which of the Q2. The case study illustrates which of the following?following?Q3. In a text editing exercise, it is believed that a Q3. In a text editing exercise, it is believed that a user decides to use the mouse to move the user decides to use the mouse to move the cursor if the cursor is more than 2 lines from cursor if the cursor is more than 2 lines from where they will edit the text, but uses the arrow where they will edit the text, but uses the arrow keys otherwise. In a GOMS model, this keys otherwise. In a GOMS model, this represents…represents…

Usability/HCI OverviewUsability/HCI Overview‘‘Iterative’ cycle for system development.Iterative’ cycle for system development.

Criteria for designing usable softwareCriteria for designing usable software

Norman’s ‘Seven stages of action model’ in relation to Norman’s ‘Seven stages of action model’ in relation to goals and actual implemented systemgoals and actual implemented system

Briefly consider Norman’s ‘Seven stages of action model’ Briefly consider Norman’s ‘Seven stages of action model’ in relation to goals and actual implemented systemin relation to goals and actual implemented system

GOMS model. What is it; what is the purpose of a GOMS model. What is it; what is the purpose of a GOMS analysis?GOMS analysis?– Review illustration of benefitsReview illustration of benefits

Number of users in evaluation – thinking aloud testNumber of users in evaluation – thinking aloud test

Real life example where good/bad computer Real life example where good/bad computer interface design can be a life or death matterinterface design can be a life or death matter

Consider the example of Ray Cox at the Consider the example of Ray Cox at the East Texas Cancer Center (p.383 in text).East Texas Cancer Center (p.383 in text).– Technician viewed ‘monitor not plugged in’ as Technician viewed ‘monitor not plugged in’ as

normal; and she’d used the controls dozens of normal; and she’d used the controls dozens of times – it was pretty simple.times – it was pretty simple.

– However, there was a flaw in the software- However, there was a flaw in the software- when edit function was used very quickly. when edit function was used very quickly.

Human factors in computers: Human factors in computers: – hardware design, hardware design, – software functionality, software functionality, – interface design.interface design.

See ‘iterative’ cycle for system See ‘iterative’ cycle for system development.development.

See Figure 15.1 (p.387 in text). See Figure 15.1 (p.387 in text).

– Understanding – Design – EvaluationUnderstanding – Design – Evaluation

– Other authorities on HCI include: Nielson, Other authorities on HCI include: Nielson, Norman, LandauerNorman, Landauer

Understanding

Evaluation Design

See ‘iterative’ cycle for system See ‘iterative’ cycle for system development.development.

Criteria for designing usable Criteria for designing usable software software (Nielson, 1994)(Nielson, 1994)

Learnability Learnability should be easy to learn – to get rapid start in workshould be easy to learn – to get rapid start in work

EfficiencyEfficiencySo that user has high productivity once learned.So that user has high productivity once learned.

MemorabilityMemorabilityCasual user should be able to return after period of time w/out re-learningCasual user should be able to return after period of time w/out re-learning

ErrorsErrorsHelpful if system enables low error rate and easy error recovery.Helpful if system enables low error rate and easy error recovery.

SatisfactionSatisfactionPleasant to use; Users should be ‘subjectively’ satisfied.Pleasant to use; Users should be ‘subjectively’ satisfied.

Priority may be greater or lower based on task characteristics.Priority may be greater or lower based on task characteristics.– see p.59 in new edition of text (Ch.3 on Usability Testing for additional see p.59 in new edition of text (Ch.3 on Usability Testing for additional

information). information).

Norman’s ‘Seven stages of action model’ in relation Norman’s ‘Seven stages of action model’ in relation to goals and actual implemented systemto goals and actual implemented system

See figure 15.2 which consists of two bridges and seven See figure 15.2 which consists of two bridges and seven steps as outlined on p. 390-391 in text.steps as outlined on p. 390-391 in text.– User starts with goals, needs to know what to do, and howUser starts with goals, needs to know what to do, and how– To bridge the Gulf of Execution (bridge)To bridge the Gulf of Execution (bridge)– Bridged (by designer) through good controls (ch.9).Bridged (by designer) through good controls (ch.9).– User evaluates to determine (bridge) how well goals matched User evaluates to determine (bridge) how well goals matched

resultsresults

Execution BridgeExecution Bridge– Intention – send emailIntention – send email– Action specification – necessary sequenceAction specification – necessary sequence– Interface mechanismInterface mechanism

Norman’s ‘Seven stages of action model’ in relation Norman’s ‘Seven stages of action model’ in relation to goals and actual implemented systemto goals and actual implemented system

Briefly consider Norman’s ‘Seven stages of action Briefly consider Norman’s ‘Seven stages of action model’ in relation to goals and actual implemented model’ in relation to goals and actual implemented

systemsystem

Evaluation BridgeEvaluation Bridge– Interface mechanism/displayInterface mechanism/display– InterpretationInterpretation– EvaluationEvaluation

Closing the gap between ‘state of system’ Closing the gap between ‘state of system’ and ‘psychological’ model of system state and ‘psychological’ model of system state is a challenge for designersis a challenge for designers

QOTD. Q1. What is a GOMS model? What is the QOTD. Q1. What is a GOMS model? What is the purpose of a GOMS analysis?purpose of a GOMS analysis?

See p. 392-393 in text as well as p. 45 in Ch.3 – See p. 392-393 in text as well as p. 45 in Ch.3 – considering Task Data).considering Task Data).Goals, Operators, Methods, Selection RulesGoals, Operators, Methods, Selection Rules – – Predictive Models of Task PerformancePredictive Models of Task Performance– Eg. Goal – write email. Sub-goals- make blank page to write on Eg. Goal – write email. Sub-goals- make blank page to write on

– – – Methods – sequence of steps – perceptual, cognitive or motor Methods – sequence of steps – perceptual, cognitive or motor

operatorsoperators– Since several methods can be used to achieve the sub-goals, Since several methods can be used to achieve the sub-goals,

selection rules are developed/postulated to suggest/identify selection rules are developed/postulated to suggest/identify under what conditions a user will use one method or another. under what conditions a user will use one method or another.

– Eg. Method of ‘print’ could be ‘press printer icon’, mouse click Eg. Method of ‘print’ could be ‘press printer icon’, mouse click file, print, ok, or choose key sequence (eg. Alt-f-p or Ctrl-p). file, print, ok, or choose key sequence (eg. Alt-f-p or Ctrl-p).

– Designers/developers may try to determine when what Designers/developers may try to determine when what conditions lead to certain methods (to predict performance and conditions lead to certain methods (to predict performance and learning time).learning time).

Recall in HCI: GOMS model & GOMS analysis?Recall in HCI: GOMS model & GOMS analysis?

Goals, Operators, Methods, Selection Goals, Operators, Methods, Selection RulesRules – Predictive Models of Task PerformancePredictive Models of Task Performance

See p. 392-393 in text as well as p. 45 in Ch.3 – See p. 392-393 in text as well as p. 45 in Ch.3 – considering Task Data.considering Task Data.

– In HCI this is a keystroke level model of human-In HCI this is a keystroke level model of human-machine interactionmachine interaction

Eg. Goal – write email. Eg. Goal – write email. – Sub-goal- make blank page to write onSub-goal- make blank page to write on– So the subgoals can have equivalent related to So the subgoals can have equivalent related to

the operatorsthe operators– Eg. Choose menu item ‘compose new email’Eg. Choose menu item ‘compose new email’

OperatorsOperators are the methods and procedures that are the methods and procedures that the system makes available the system makes available – eg. Elementary motor or cognitive acts needed to eg. Elementary motor or cognitive acts needed to

change the system state – for instance, selecting an change the system state – for instance, selecting an item in a menu.item in a menu.

– Or the ‘goal’ to ‘edit chapter 15 title’ might consist of Or the ‘goal’ to ‘edit chapter 15 title’ might consist of subgoals with equivalent operators: ‘open file’, find subgoals with equivalent operators: ‘open file’, find heading’, ‘delete heading’.heading’, ‘delete heading’.

Methods – sequence of steps – Methods – sequence of steps – – Perceptual – visual or auditoryPerceptual – visual or auditory– Cognitive – Cognitive – operatoroperator decidesdecides (next procedures)(next procedures)

whether to listen, respond/speak, or transfer customer whether to listen, respond/speak, or transfer customer – Motor operations – left hand, right hand, eye Motor operations – left hand, right hand, eye

movementsmovements

Selection RulesSelection Rules - Since several methods can be used - Since several methods can be used to achieve the sub-goals, to achieve the sub-goals, selection rulesselection rules are are developed/postulated to suggest/identify under what developed/postulated to suggest/identify under what conditions a user will use one method or another. conditions a user will use one method or another. – Eg. Method of ‘print’ could be ‘press printer icon’, mouse click Eg. Method of ‘print’ could be ‘press printer icon’, mouse click

file, print, ok, or choose key sequence (eg. Alt-f-p or Ctrl-p). file, print, ok, or choose key sequence (eg. Alt-f-p or Ctrl-p). – Selection rule: choose mouse if line to be edited is +/- 2 lines Selection rule: choose mouse if line to be edited is +/- 2 lines

from cursor current position.from cursor current position.

Designers/developers may try to determine when what Designers/developers may try to determine when what conditions lead to certain methods (to predict conditions lead to certain methods (to predict performance and learning time).performance and learning time).

Recall illustration of benefits of using the GOMS Recall illustration of benefits of using the GOMS

model (NYNEX example).model (NYNEX example). This case was initially described by Gray et al. 1993 in the This case was initially described by Gray et al. 1993 in the journal called Human Computer Interaction.journal called Human Computer Interaction.

See p.394 Case study in text.See p.394 Case study in text.

Gray (1993) et al. used the GOMS model to ‘evaluate’ a new Gray (1993) et al. used the GOMS model to ‘evaluate’ a new operator workstation for NYNEX (NY Phone Company).operator workstation for NYNEX (NY Phone Company).– Why there was a 3-4% increase in performance time even Why there was a 3-4% increase in performance time even

though number of keystrokes was reduced? though number of keystrokes was reduced?

– (consider the keystrokes on the ‘critical path’)(consider the keystrokes on the ‘critical path’)

See also 2 sided handout from ‘Intro to Ergonomics’ BridgerSee also 2 sided handout from ‘Intro to Ergonomics’ Bridger (p.459-461)(p.459-461)– R.S. Bridger, 2003, Introduction to Ergonomics, 2R.S. Bridger, 2003, Introduction to Ergonomics, 2ndnd Ed., Taylor and Francis Ed., Taylor and Francis

Publishers: UK.Publishers: UK.

Recall illustration of benefits of using the GOMS Recall illustration of benefits of using the GOMS

model (NYNEX example).model (NYNEX example). See also 2 sided handout on course webpage from See also 2 sided handout on course webpage from ‘Intro to Ergonomics’ Bridger‘Intro to Ergonomics’ Bridger (parts of pages 459-461)(parts of pages 459-461)

Number of users in evaluationNumber of users in evaluation

Thinking aloud test –Wickens, Thinking aloud test –Wickens, see p. 409 in text,see p. 409 in text, refers to T.Landauer;refers to T.Landauer; some refer to J.Nielsonsome refer to J.Nielson (1994)(1994)..

after 5-6 people, the benefit of additional after 5-6 people, the benefit of additional people diminishes. people diminishes.

Suggests developers would be better off Suggests developers would be better off making software changes before running making software changes before running additional subjects.additional subjects.

IE 486 Lecture 8 - QOTDIE 486 Lecture 8 - QOTD

Q2. The case study illustrates which of the Q2. The case study illustrates which of the following?following?

a. the benefits of a task analysisa. the benefits of a task analysis

b. the barriers to organizational changeb. the barriers to organizational change

c. the information processing modelc. the information processing model

d. all of the aboved. all of the above

e. none of the abovee. none of the above

QOTD QOTD

Q.3. In a text editing exercise, it is believed that Q.3. In a text editing exercise, it is believed that a user decides to use the mouse to move the a user decides to use the mouse to move the cursor if the cursor is more than 2 lines from cursor if the cursor is more than 2 lines from where they will edit the text, but uses the arrow where they will edit the text, but uses the arrow keys otherwise. In a GOMS model, this keys otherwise. In a GOMS model, this represents…represents…a. user goalsa. user goalsb. methods b. methods c. cognitive operatorsc. cognitive operatorsd. all of the aboved. all of the abovee. none of the above e. none of the above