Usability and Human Factors

1. Usability and Human Factors Unit 3: Cognition and Human Performance Lecture b This material (Comp 15 Unit 3) was developed by Columbia University, funded by the Department of Health and Human Services, Office of the National Coordinator for Health Information Technology under Award Number 1U24OC000003. This material was updated by The University of Texas Health Science Center at Houston under Award Number 90WT0006. This work is licensed under the Creative Commons Attribution-NonCommercial-ShareAlike 4.0 International License. To view a copy of this license, visit http://creativecommons.org/licenses/by-nc-sa/4.0/.

2. Cognition and Human PerformanceLecture b – Learning Objectives • Describe the impact of different kinds of representation on cognition as it applies to human computer interaction and web design (Lecture a) • Describe how humans process information and obtain skills (Lecture a) • Describe the Gestalt principles of perception and their relevance to human computer interaction and cognitive theory (Lecture a) • Describe the processes of memory and their relationship to web-design (Lecture b) • Describe the cognitive constructs for mental representation (Lecture b) • Describe the cognitive constructs for mental representation (Lecture c) • Explain how cognition and human performance models should inform iterative design processes (Lecture c)

3. Memory Short term sensory storage Working Memory Long Term Memory

4. Memory Processes • Encoding: process of putting things into memory • Storage: how information is maintained in memory • Retrieval: accessing information from memory

5. Working memory (WM) • WM is the short-term memory or temporary store that keeps information “active” • When processing in WM, we bring information from the sensory register and long-term memory (LTM) into WM • Information is encoded • WM has limitations • The limitations of WM have major implications for system design

6. WM Capacity Constraints • The upper limit of capacity is 7± 2 chunks of information • A “chunk” is the unit of WM space, defined jointly by the physical and cognitive properties that bind items within the chunk together (Miller, 1956)

7. Long-term memory (LTM) • LTM provides a mechanism for storing information and retrieving it at a later time • Relatively permanent storage system • Highly organized knowledge structures • Different types of knowledge

8. Carving Up Knowledge • Factual Knowledge • Risk factors for coronary artery disease • Declarative or Conceptual Knowledge • Deeper level of understanding • Part of a network of knowledge and beliefs • Procedural Knowledge • How to perform various actions • Decision rules in guidelines • Collaborative Knowledge (people and artifacts) • Individual and collective

9. Cognitive Constructs for Mental Representation • Schema • Mental Images • Representation of perceiving some object, event, or scene • Propositions • Capture the meaning of linguistic and other symbolic forms • Mental models

10. Schemata

11. Schemata (Cont’d – 1) • To process information with the use of a schema is to determine which model best fits the incoming information. • Does the animal at a distance more closely resemble a dog or a cat? • Features of schemata. • constants (all birds have wings) and • variables (chairs can have between 1 and 4 legs); • Aimed at evaluating how well they fit to the data being processed • Does the patient’s chest pain seem more like a case of heartburn or might he be having a heart attack?

12. Bird Schema • Type: • animal • Locomotion: • flies* (default value) • walks • swims • Communication: • sings* • squawks • Size: • small* • medium • large • Habitat: • trees* • lands • waters • Food: • insects* • seeds • fish • Colors: • Variable (Kaufman, 2010)

13. Scripts • Knowledge structure captures general information about routine events • eating in a restaurant, • attending a lecture, • the visit to the Dentist’s office • Scripts have typical roles • Customers, waiter, cook • Professor, teaching assistants, students • Dentist, assistant, patient, and the drill

14. Scripts (Cont’d – 1) • Scripts have entry conditions • Customers are hungry • Students are thirsty for knowledge • Patient needs 6 cavities filled, some root canal work and a bridge installed • Scripts elicit elaborated knowledge of an event type • We can fill in or infer the scenes and actions that are not explicitly mentioned

15. Cognition and Human Performance Summary – Lecture b • Structure of memory with a particular focus on working memory • Cognitive constructs for mental representation • Schemata • Scripts • Next lecture: mental models and distributed cognition

16. Cognition and Human PerformanceReferences – Lecture b References Preece, J. Rogers, Y. & Sharp, H. (2007) Interaction Design: Beyond Human-Computer Interaction. 2nd Edition. New York, NY: John Wiley & Sons. Miller, G. A. (1956). The magical number seven, plus or minus two: some limits on our capacity for processing information. Psychological review, 63(2), 81. Images: Slide 12: Kaufman, D. (2010). Personal image of bird schema. Department of Biomedical Informatics, Columbia University Medical Center.

17. Usability and Human FactorsCognition and Human PerformanceLecture b This material was developed by Columbia University, funded by the Department of Health and Human Services, Office of the National Coordinator for Health Information Technology under Award Number 1U24OC000003. This material was updated by The University of Texas Health Science Center at Houston under Award Number 90WT0006.