1. 1 CMT 3210: Understanding the Human Element in HCI Week 7: Memory and Attention

2. 2 Topics: zMemory zAttention zMultimodal systems

3. 3 1. Memory zCognitive models of memory zActivation in memory zImplications of memory models zApplications of memory models

4. 4 A Model of Memory zThree memory stores ysensory memory xinput buffer xvisual or acoustic yshort term memory x‘scratchpad’ store xvisual or acoustic yLong term memory xstores facts and meanings xsemantically organised Sensory memory Short term memory Long term memory

5. 5 Primary Memory and Recency Effects zFree recall experiments ysuperiority of items at the end of the list: primary memory, recency effect ysuperiority of items at the begin of the list: increased attention, transfer to longer term memory systems Chance of recall Position in list LTM STM Recall after 30 s Imme- diate recall

6. 6 Revised Memory Model zWorking memory is a subset of LTM. zItems are semantically linked. zitems in working memory are activated. zactivation is supplied from other linked chunks and from sensory input. Sensory memory Working memory Long term memory

7. 7 Revised Human Processor Model and Related Memory Visual image store Working memory Long term memory Auditory image store Visual StimulusSound Perceptual processor Motor processor Cognitive Processor

8. 8 The Central Executive zAttentional co-ordinating system in the working memory zsubsidiary slave systems yvisuo-spatial sketchpad yarticulatory loop zInterferrence: yWatching and talking Visuo-spatial sketchpad Central executive Articulatory loop

9. 9 Long Term Memory zOrganised as a network of connected chunks of knowledge zactive chunks are in the working memory zactivation spreads through the network ystrength of connection yretrieval of items into WM

10. 10 Long Term Memory zExample ythe dog chewed the food ythe cat stole the food ythe dog chased the cat dog cat food stole chewedchased

11. 11 Consequences for Interface Design zChunking and working memory: y7 ± 2 items, in menus, boxes, slides, grouping, etc. zmemory decay. y history of actions. zinterference. yno competing activities, focus the user’s attention.

12. 12 Remembering zRecognition ystimulus causes activation of LTM items (into WM) zRecall yno stimulus; involves searching, more effort required z Example: yrecognition: use of icons yrecall: command line key combinations e.g. Control- X, control-C z Use recognition instead of recall!

13. 13 Post Completion Error zGoals and sub goals stored and chunks in memory zSub-goals removed once the main goal is achieved zGoals supply activation to sub- goals Goal Sub-goal activation

14. 14 Example: Photocopying Main goal: Make a photocopy Sub-goal: put in original Sub-goal: insert card Sub-goal: carry out copying Sub-goal: retrieve original Sub-goal: retrieve card

15. 15 Memory Functions zFor past history: autobiographical, retrospective zfor things to do in the future: prospective zfor facts: semantic zfor events: episodic zfor how to do it knowledge: procedural zAre these different memory systems?

16. 16 Consequences for Interface Design zUse recognition instead of recall (icons) zavoid potential post completion errors zsupport accumulation of procedural knowledge

17. 17 2. Attention zWhat is attention. ymany competing stimuli, but. yonly limited capacity. ytherefore need to focus, and select. zVisual attention. ybased on location and colour. zAuditory attention. ybased on pitch, timbre, intensity, etc.

18. 18 Models of Attention zDivided attentionz Focused attention Available capacity Possible activities senses Short term store Processing

19. 19 Focused Attention zOnly one thing can be the focus of attention zAttention focus is voluntary or involuntary zFactors affecting attentional focus ymeaningfulness ystructure of display yuse of colour, intensity, yuse of modalities

20. 20 Example 1 (Preece, P. 103)

21. 21 Example 2: Attention in the Wrong Place zPrior to landing pilots found a fault zThree crew engaged in fixing the problem zAccidentally turned off autopilot; aircraft started to descend zdespite low altitude warning, low altimeter reading & warning, visual alert, crew believed to be at 2000 feet zno one noticed the problem; aircraft crashed

22. 22 Attention and Automatic Action zFrequent activities become automatic. zCarried out without conscious attention. zUser does not make conscious decision. zRequiring confirmation does not necessarily reduce errors!

23. 23 Possible Solution? The action you requested cannot be undone, it will cause permanent loss of data. If you really want to delete the information, please type backwards the tenth word in this box.

24. 24 Consequences zDesign to assist attentional focus in the right place. zHelp user to. yattend his/her task not the interface. ydecide what to focus on, based on their tasks, interest,etc. yto stay focused, do not provide unnecessary distractions. ystructure his/her task, e.g. help.

25. 25 Consequences zCreate distraction, when really necessary! zUse alerts (only) when appropriate!

26. 26 3. Multimodal Systems zModality = communication channel zPeople can interact using multiple modalities yexample: pointing at a person and saying “you” zMixture of modalities in user interfaces ycommon for output (e.g. visual and acoustic) yless so for input (e.g. either keyboard or speech)

27. 27 Coherence in Multimodal Systems zAbility to process and combine streams of information on different communication channels. zProblem: interference. ysee also central executive unit with subsidiary slave systems. yvisuo-spatial sketchpad. yarticulatory loop.

28. 28 Coherence & Interference zHow easy is it to ydrive and talk? ySpeak or listen while reading complex texts? ywrite and listen to music? yMonitor children and listen to the radio?

29. 29 Coherence zIf streams of input are incoherent, further problems arise y e.g. lip synchronisation problems in films ye.g. alert colour for confirmation message zUser gets confused

30. 30 Summary zMemory models ysensory, long term, working memory ycentral executive zAttention yfocused and divided attention zMultimodal systems yseveral sensory input streams to be combined yinterference and incoherence

31. 31 Further Reading zPreece, J. et al. (1994) Human Computer Interaction zDix et al. (1998) Human Computer Interaction zGross, R. (1992) Psychology: The Science of Mind and Behaviour (or any similar textbook about cognitive psychology) zJohnson, P. (1992) Human Computer Interaction: Psychology, task analysis and software engineering zRaskin, J. (2000) The Humane Interface: New direction for designing interactive systems. Addison Wesley