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

Associate ProfessorAssociate Professor

Lecture 5 – Cognition & Information ProcessingLecture 5 – Cognition & Information Processing

Tues. Jan. 30, 2007Tues. Jan. 30, 2007

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

An overview capabilities and limitations of our An overview capabilities and limitations of our information processing related to HF Designinformation processing related to HF Design

1. An example re: limitations in cognition1. An example re: limitations in cognition

2. Information processing models2. Information processing models

3. Object and pattern recognition3. Object and pattern recognition

4. Transfer to working memory4. Transfer to working memory

5. Working memory5. Working memory

6. Long term memory 6. Long term memory

7. Attention and mental resources7. Attention and mental resources

8. Conclusions8. Conclusions

IE 486 - Lecture 5 - QOTDIE 486 - Lecture 5 - QOTD

QOTD 1 Ambiguous or unclear sensory QOTD 1 Ambiguous or unclear sensory features can be recognized as different features can be recognized as different objects depending on context. This objects depending on context. This illustrates…___________.illustrates…___________.

QOTD 2 The human sensory register can QOTD 2 The human sensory register can hold _____________. This illustrates hold _____________. This illustrates ___________.___________.

1. An example re: limitations in cognition1. An example re: limitations in cognition

Drive to downtown mall for holiday shoppingDrive to downtown mall for holiday shopping– Enter the mall’s 10 story parking structureEnter the mall’s 10 story parking structure

Drive up spiral until you find a space near the Drive up spiral until you find a space near the elevatorelevator– Proceed down the elevator and into the mallProceed down the elevator and into the mall

5 hours later bring many bags of gifts for friends 5 hours later bring many bags of gifts for friends and relativesand relatives– Return to the parking garageReturn to the parking garage

Get out on 6th floor but can’t find the car!Get out on 6th floor but can’t find the car!– then wander to two other levels before finally locating then wander to two other levels before finally locating

the car.the car.

2. Information processing models2. Information processing models

Perceptual EncodingPerceptual Encoding

Central ProcessingCentral Processing

RespondingResponding

2. Information processing models2. Information processing models

Perceptual EncodingPerceptual Encoding – includes issues of chapter 4 & 5 on sensesincludes issues of chapter 4 & 5 on senses– Bring knowledge to the sensory input; give it meaningBring knowledge to the sensory input; give it meaning

Central ProcessingCentral Processing– Includes concerns about ‘attentional resources’ and Includes concerns about ‘attentional resources’ and

issues related to perception, memory and issues related to perception, memory and thoughtsthoughts about the need for decision making – related to chapter about the need for decision making – related to chapter 66

RespondingResponding– The line between decision making and problem solving The line between decision making and problem solving

is a bit blurredis a bit blurred– Includes decision making – chapter 7Includes decision making – chapter 7

For additional detail see figure 6-1 p. 122For additional detail see figure 6-1 p. 122

Information processing modelInformation processing model (p.122)(p.122)

3. Object and pattern recognition3. Object and pattern recognition

Feature analysisFeature analysis

It is a 3 step processIt is a 3 step process according to Anderson according to Anderson– Break into component featuresBreak into component features– Draw out stored patterns from long term memory to Draw out stored patterns from long term memory to

match the features match the features – Decide which stored pattern is the best matchDecide which stored pattern is the best match

3. Object and pattern recognition3. Object and pattern recognition

Feature analysisFeature analysis

It is a 3 step process according to AndersonIt is a 3 step process according to Anderson– Break into component featuresBreak into component features– Draw out stored patterns from long term memory to Draw out stored patterns from long term memory to

match the features match the features – Decide which stored pattern is the best matchDecide which stored pattern is the best match

Eg. If we see the word ‘the’ enough times, Eg. If we see the word ‘the’ enough times, – we begin to process it automatically as a global shapewe begin to process it automatically as a global shape

rather than analyze the individual features (parts of rather than analyze the individual features (parts of letters and individual letters).letters and individual letters).

3. Object and pattern recognition3. Object and pattern recognition

Top-down and bottom-up processingTop-down and bottom-up processing– Ambiguous sensory features can be recognized as Ambiguous sensory features can be recognized as

different objects depending on context.different objects depending on context.

Illustrates the benefits of ‘redundancy’ in Illustrates the benefits of ‘redundancy’ in presenting information.presenting information.– We may not need to know all of the letters of the word We may not need to know all of the letters of the word

to recognize it.to recognize it.

3. Object and pattern recognition3. Object and pattern recognition

QOTD 1 :QOTD 1 : Top-down and bottom-up processing Top-down and bottom-up processing– Ambiguous sensory features can be recognized as Ambiguous sensory features can be recognized as

different objects depending on context.different objects depending on context.

Illustrates the benefits of ‘redundancy’ in Illustrates the benefits of ‘redundancy’ in presenting information.presenting information.– We may not need to know all of the letters of the word We may not need to know all of the letters of the word

to recognize it.to recognize it.

I cxn rxplxce xvexy txirx lextex of x sextexce xitx an x, anx I cxn rxplxce xvexy txirx lextex of x sextexce xitx an x, anx yox stxll xan xanxge xo rxad xt – ix wixh sxme xifxicxltx.yox stxll xan xanxge xo rxad xt – ix wixh sxme xifxicxltx.

3. Object and pattern recognition3. Object and pattern recognition

Top-down and bottom-up processingTop-down and bottom-up processing– Ambiguous sensory features can be recognized as Ambiguous sensory features can be recognized as

different objects depending on context.different objects depending on context.

Illustrates the benefits of ‘redundancy’ in Illustrates the benefits of ‘redundancy’ in presenting information.presenting information.– We may not need to know all of the letters of the word We may not need to know all of the letters of the word

to recognize it.to recognize it.

I cxn rxplxce xvexy txirx lextex of x sextexce xitx an x, anx I cxn rxplxce xvexy txirx lextex of x sextexce xitx an x, anx yox stxll xan xanxge xo rxad xt – ix wixh sxme xifxicxltx.yox stxll xan xanxge xo rxad xt – ix wixh sxme xifxicxltx.

Typically we think of object recognition as ‘bottom Typically we think of object recognition as ‘bottom up’ (eg. See the round object - ball). up’ (eg. See the round object - ball). – Yet context may tell us if it is a basketball or beach ball.Yet context may tell us if it is a basketball or beach ball.

3. Object and pattern recognition3. Object and pattern recognition

When stimulus is high quality, bottom up When stimulus is high quality, bottom up processing will be most influential.processing will be most influential.– As quality of the signal/stimulus is degraded,As quality of the signal/stimulus is degraded,

increases in context and redundancy will be increases in context and redundancy will be necessary necessary

to enable more top-down processing and high level to enable more top-down processing and high level of recognition.of recognition.

3. Object and pattern recognition3. Object and pattern recognition

When stimulus is high quality, bottom up When stimulus is high quality, bottom up processing will be most influential.processing will be most influential.– As quality of the signal/stimulus is degraded,As quality of the signal/stimulus is degraded,

increases in context and redundancy will be increases in context and redundancy will be necessary necessary

to enable more top-down processing and high level to enable more top-down processing and high level of recognition.of recognition.

ImplicationsImplications– Designers should not do usability testing for ‘icons’ in a Designers should not do usability testing for ‘icons’ in a

lab lab

without considering surrounding environment and/or without considering surrounding environment and/or task context.task context.

4. Transfer to working memory4. Transfer to working memory

The human sensory register can holdThe human sensory register can hold – visual information for about 1 secondvisual information for about 1 second– auditory information for about 3-5 secondsauditory information for about 3-5 seconds

QOTD 2 : Consider: what does this illustrate?QOTD 2 : Consider: what does this illustrate?

4. Transfer to working memory4. Transfer to working memory

Limitations in information processing Limitations in information processing

Only a limited amount of information can be Only a limited amount of information can be brought from sensory to working memorybrought from sensory to working memory – Typically overlooked in system designTypically overlooked in system design

4. Transfer to working memory4. Transfer to working memory

Limitations in information processing Limitations in information processing

Only a limited amount of information can be Only a limited amount of information can be brought from sensory to working memorybrought from sensory to working memory – Typically overlooked in system designTypically overlooked in system design

Working memory is limited in two ways:Working memory is limited in two ways:– ““Capacity” and “time”Capacity” and “time”

Working memory is limited inWorking memory is limited in‘‘how muchhow much’ information can be kept active’ information can be kept active

‘‘how long’how long’ it can be kept active it can be kept active

5. Working memory5. Working memory

A railroad switchman forgot he moved a train to an active track. The ensuing crash killed over 200 people

Working memory holds two different types of information Verbal and spatial

5. Working memory5. Working memory

A railroad switchman forgot he moved a train to an active track. The ensuing crash killed over 200 people

Working memory holds two different types of information Verbal and spatial

Working memory is the temporary holding of information that is active

Long term memory is considered the reactivation of information

5. Working memory5. Working memory

Working memory must be able to accommodate the demands and support active problem-solvingRecall: consideration given to capacity and time

limitations Capacity

7 +/- 2 chunksPhysical and cognitive properties that bind items togetherEg. 8 4 7 9 has 4 chunks28 36 45 89 also has 4 chunks

5. Working memory5. Working memory

Working memory must be able to accommodate the demands and support active problem-solvingRecall: consideration given to capacity and time

limitations Capacity

7 +/- 2 chunksPhysical and cognitive properties that bind items togetherEg. 8 4 7 9 has 4 chunks28 36 45 89 also has 4 chunks

Chunking reduces the number of items in working memory and makes use of meaningful associations.Also, material can be more easily rehearsed.

5. Working memory5. Working memory

Some rules of thumb for designMinimize working memory loadGive visual redundancy when possible

Exploit chunkingNote: letters may be better than numbersEg. 1-800-663-5900 has 8 chunks while 1-800 GET HELP

has 3.

5. Working memory5. Working memory

Some rules of thumb for designMinimize working memory loadGive visual redundancy when possible

Exploit chunkingNote: letters may be better than numbersEg. 1-800-663-5900 has 8 chunks while 1-800 GET HELP

has 3. Keep numbers separate from letters

Eg. License plates: 458 GST is preferred. Instead of 4G58ST

6. Long term memory6. Long term memory

Semantic memoryGeneral knowledge

Event memory –specific events- past and futureEpisodic memory – past event

Eg. An accident at workProspective memory – future

Eg. Remember to do something

6. Long term memory6. Long term memory

Design implicationsThe user is unlikely to develop the same level

of detail (recall) in the use of a product compared to the designer

6. Long term memory6. Long term memory

Design implicationsThe user is unlikely to develop the same level

of detail (recall) in the use of a product compared to the designer

Therefore, when possible, it is a good idea to:Encourage frequent use of information –

Take advantage of frequency and recency then over time, the task may become more automatic

Standardize and use memory aidsEg. Give list of instructions for sending fax

Carefully design information to be remembered

Make it meaningful and avoid the use of technical jargon when possible

7. Attention and mental resources7. Attention and mental resources

If we devote cognitive resources to one activity, others are likely to sufferEg. Study of the use of cell phones and

driving suggests that accidents are 5x more likely

The rate is roughly equivalent to driving drunk Consider multiple resources

Eg. One can not read a book and watch tv at the same time.

However, one can listen to the spoken version of the book while watching tv.

Visual and auditory processing requires separate resources.

8. Conclusions8. Conclusions

Some general design implications Consider: issues related to

Divided attention, controlled vs. automatic processing & multiple resources