Instructor: Vincent Duffy, Ph.D. Associate Professor Lecture 5 – Cognition & Information Processing Tues. Jan. 30, 2007 IE 486 Work Analysis & Design II

An overview capabilities and limitations of our information processing related to HF Design 1. An example re: limitations in cognition 2. Information processing models 3. Object and pattern recognition 4. Transfer to working memory 5. Working memory 6. Long term memory 7. Attention and mental resources 8. Conclusions

IE Lecture 5 - QOTD QOTD 1 Ambiguous or unclear sensory features can be recognized as different objects depending on context. This illustrates…___________. QOTD 2 The human sensory register can hold _____________. This illustrates ___________.

1. An example re: limitations in cognition Drive to downtown mall for holiday shopping –Enter the mall’s 10 story parking structure Drive up spiral until you find a space near the elevator –Proceed down the elevator and into the mall 5 hours later bring many bags of gifts for friends and relatives –Return to the parking garage Get out on 6th floor but can’t find the car! –then wander to two other levels before finally locating the car.

2. Information processing models Perceptual Encoding Central Processing Responding

2. Information processing models Perceptual Encoding –includes issues of chapter 4 & 5 on senses –Bring knowledge to the sensory input; give it meaning Central Processing –Includes concerns about ‘attentional resources’ and issues related to perception, memory and thoughts about the need for decision making – related to chapter 6 Responding –The line between decision making and problem solving is a bit blurred –Includes decision making – chapter 7 For additional detail see figure 6-1 p. 122

Information processing model (p.122)

3. Object and pattern recognition Feature analysis It is a 3 step process according to Anderson –Break into component features –Draw out stored patterns from long term memory to match the features –Decide which stored pattern is the best match

3. Object and pattern recognition Feature analysis It is a 3 step process according to Anderson –Break into component features –Draw out stored patterns from long term memory to match the features –Decide which stored pattern is the best match Eg. If we see the word ‘the’ enough times, –we begin to process it automatically as a global shape rather than analyze the individual features (parts of letters and individual letters).

3. Object and pattern recognition Top-down and bottom-up processing –Ambiguous sensory features can be recognized as different objects depending on context. Illustrates the benefits of ‘redundancy’ in presenting information. –We may not need to know all of the letters of the word to recognize it.

3. Object and pattern recognition QOTD 1 : Top-down and bottom-up processing –Ambiguous sensory features can be recognized as different objects depending on context. Illustrates the benefits of ‘redundancy’ in presenting information. –We may not need to know all of the letters of the word to recognize it. I cxn rxplxce xvexy txirx lextex of x sextexce xitx an x, anx yox stxll xan xanxge xo rxad xt – ix wixh sxme xifxicxltx.

3. Object and pattern recognition Top-down and bottom-up processing –Ambiguous sensory features can be recognized as different objects depending on context. Illustrates the benefits of ‘redundancy’ in presenting information. –We may not need to know all of the letters of the word to recognize it. I cxn rxplxce xvexy txirx lextex of x sextexce xitx an x, anx yox stxll xan xanxge xo rxad xt – ix wixh sxme xifxicxltx. Typically we think of object recognition as ‘bottom up’ (eg. See the round object - ball). –Yet context may tell us if it is a basketball or beach ball.

3. Object and pattern recognition When stimulus is high quality, bottom up processing will be most influential. –As quality of the signal/stimulus is degraded, increases in context and redundancy will be necessary to enable more top-down processing and high level of recognition.

3. Object and pattern recognition When stimulus is high quality, bottom up processing will be most influential. –As quality of the signal/stimulus is degraded, increases in context and redundancy will be necessary to enable more top-down processing and high level of recognition. Implications –Designers should not do usability testing for ‘icons’ in a lab without considering surrounding environment and/or task context.

4. Transfer to working memory The human sensory register can hold –visual information for about 1 second –auditory information for about 3-5 seconds QOTD 2 : Consider: what does this illustrate?

4. Transfer to working memory Limitations in information processing Only a limited amount of information can be brought from sensory to working memory –Typically overlooked in system design

4. Transfer to working memory Limitations in information processing Only a limited amount of information can be brought from sensory to working memory –Typically overlooked in system design Working memory is limited in two ways: –“Capacity” and “time” Working memory is limited in ‘how much’ information can be kept active ‘how long’ it can be kept active

5. 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 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 memory Working memory must be able to accommodate the demands and support active problem-solving Recall: consideration given to capacity and time limitations Capacity 7 +/- 2 chunks Physical and cognitive properties that bind items together Eg has 4 chunks also has 4 chunks

5. Working memory Working memory must be able to accommodate the demands and support active problem-solving Recall: consideration given to capacity and time limitations Capacity 7 +/- 2 chunks Physical and cognitive properties that bind items together Eg has 4 chunks 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 memory Some rules of thumb for design Minimize working memory load Give visual redundancy when possible Exploit chunking Note: letters may be better than numbers Eg has 8 chunks while GET HELP has 3.

5. Working memory Some rules of thumb for design Minimize working memory load Give visual redundancy when possible Exploit chunking Note: letters may be better than numbers Eg has 8 chunks while GET HELP has 3. Keep numbers separate from letters Eg. License plates: 458 GST is preferred. Instead of 4G58ST

6. Long term memory Semantic memory General knowledge Event memory –specific events- past and future Episodic memory – past event Eg. An accident at work Prospective memory – future Eg. Remember to do something

6. Long term memory Design implications The user is unlikely to develop the same level of detail (recall) in the use of a product compared to the designer

6. Long term memory Design implications The 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 aids Eg. 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 resources If we devote cognitive resources to one activity, others are likely to suffer Eg. 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. Conclusions Some general design implications Consider: issues related to Divided attention, controlled vs. automatic processing & multiple resources