Week 8-1: Models of Human Memory and Knowledge Useful for Design

1. Week 8-1: Models of Human Memory and Knowledge Useful for Design

2. Week 8 Topics • Lecture 8-1 • Long-term vs. Working Memory • Working Memory • Design Implications: SCR Compatibility • Lecture 8-2 • Long-term Memory • Types of Knowledge • Training

3. Human Memory • Process overview • Three stages • Encoding: operator’s extraction of relevant information from the sensory store (attended information) into working and long-term memory • Storage: types of memory codes (decay?) • Retrieval: based on environmental cues, relevant memory traces must be linked to current operator needs and retrieved • Memory failure can result from failures at any one of these stages

4. The Structure of Human Memory • Working memory vs. Long-term memory (LTM)

5. The Structure of Human Memory • Working memory (WM) vs. Long-term memory (LTM) • Phenomenological distinction • contents of working memory occupy consciousness • contents of long-term memory are unconscious unless retrieved into working memory • Behavioral evidence • working memory: Rapid “decay”, limited capacity, analog representations • long-term memory: Decay? Capacity? Analog and propositional representations • Clinical evidence: amnesiacs such as H. M. • Neurophysiological evidence: pre-frontal cortex and WM; hippocampus, LTM, and the development of LTM

6. The Structure of Working Memory • Baddeley (1985): Three sub-systems of WM • Central executive • initiates control, decision, and reasoning processes • transfers information into LTM via rehearsal and recoding • Articulatory rehearsal loop • temporary store of phonetically coded information (sounds): analog representation • Visuo-spatial sketchpad • temporary store of spatially coded information (visual images): analog representation

7. The Structure of Working Memory Working memory response Sensory Memory (iconic, echoic) Central Executive Articulatory rehearsal loop Visuo-spatial sketchpad Long-term Memory

8. Working Memory • Capacity Limits of Verbal Code • Miller (1956): 7 +/- 2 items (~3 bits) • what is an item? (features, letters, words, phrases?) • an item is defined by its code in long-term memory: the number of LTM chunks required to store an item • definition of item depends on operator’s task and experience • Capacity limits are even lower for a running memory task, Moray (1980) • Capacity limits of spatial code?

9. Working Memory: Overcoming Capacity Limits • Chunking or recoding of information • > 7+/-2 items can be remembered if items are recoded into a smaller number of larger “chunks” • Uses pre-existing knowledge in LTM to increase the capacity of Working memory Working memory response Sensory Memory (iconic, echoic) Central Executive Articulatory rehearsal loop Visuo-spatial sketchpad Long-term Memory

10. Duration of Working Memory • Temporal Limits (decay) • Working memory does not decay unless rehearsal is prevented (through distraction, inattention, etc.) • interference NOT decay • Types of interference • proactive: interference forward in time, current material prevents learning of subsequent material • retroactive: interference backward in time, current material prevents learning of previous material

11. Working Memory Interference • Interference at work: the serial position effect • primacy effect • recencyeffect • What causes these effects? • Glanzer & Cunitz (1966) retroactive interference eliminates recency effect • Glanzer (1972) reducing proactive interference for middle items reduces primacy effect

12. Working Memory: Design Implications • Training and consistency • highly trained experts chunk information more effectively due to robust LTM representations • training only helps if environment is consistent with training • Chase & Simon (1973): chess masters vs. novices • “real” board: masters have better memory • random board: no difference in memory • Barnett (1989): Verbal communication between pilots and ATC (air-traffic control) • normal communications sequence: experts better • random communications sequence: no difference

13. Working Memory: Design Implications • Capitalizing on Familiarity • make items that need to be remembered easily “chunkable” • Examples • passwords that form real words or phrases: I82MUCH • phone numbers: “1-800-collect”

14. Working Memory: Design Implications • Implications for system design (cont.) • Parsing • introduce physical discontinuities to enhance chunking • examples • phone numbers • outlining • indentations of program statements in computer programming • Sequencing Data Output • output items less likely to be remembered first • unchunked items (e.g., last 4 digits of phone number) • items from middle and end of list

15. Working Memory: Dual-Codes • Display modality and working memory codes • Dual-code Theory (Paivio, 1986) • memory for abstract vs. concrete terms • concrete terms are easier to remember due to use of both phonetic and image-based codes

16. Working Memory: SCR Compatibility • Stimulus/central processing/response compatibility (Wickens, Sandry, & Vidulich, 1983) • What is the optimum matching between stimulus (S) and working memory codes (C)? (and responses) Spatial tasks are best served by analog visual displays Verbal tasks are best served by auditory displays, unless the message is longer than 4-5 words