Chapter 2 Human Information Processing

1. Chapter 2 Human Information Processing

2. HCI as a system human computer

3. Cognitive process

4. Human informationprocessing

5. STUDYING HUMANINFORMATION PROCESSES

6. Signal detection theory Cognitive model: encoding + decision Evaluation metrics: hit rate false alarm rate (during World War II, British radar observers detected fewer of the enemy’sradar signals after 30 minutes in a radar observation shift)

7. Reaction Time (RT) • series of discrete processing stages • Subtractivemethod • selection of tasks that differ by a single stage e.g. compare the time to finda target link on two web pages that are identical except forthe number of links displayed

8. Reaction Time (RT) • series of discrete processing stages • Additivefactorsmethod • twovariablesthat affect different stages should have additive effects on RTwhile two variables that affect the same stage should haveinteractiveeffectson RT e.g. mode of iconarray (menu or dialog box), number of icons, and difficulty ofmovement had additive effects on response times

9. RT vs. accuracy

10. Neuroergonomics electroencephalograms (EEG) fMRI

11. INFORMATION PROCESSINGIN CHOICE REACTION TASKS

13. Mental rotation R R

14. Response Selection • Hick-Hymanlaw(N equallylikelyalternatives): • Compatibilityeffects • verbal-vocal, spatial-manual Simon-effect: RIGHT LEFT red Stroop-effect blue green yellow

15. Response Execution • Fitt’s low: D is distance to the target (b is differentatvariousdevices) W is targetwidth otherfactors, e.g. point-click vs. point-drag

16. PROBLEM SOLVING AND DECISION MAKING

17. Problem solving • New tasks are frequent at computers • problem space representation • initial and goal states, operations • heuristic path-finding • naive vs. expert

18. Mental model • basedoninteraction, theuser developsa representation of how the system isfunctioning for a given task • metaphors • real life (e.g. desktop) • othertasks/systems (e.g. web browsers) • human decision-makingheuristics (when the outcome associated with a choice is uncertain) e.g. anchoring heuristic involves making a judgmentregarding probabilities of alternative states based on initialinformation

19. HUMAN MEMORY IN INFORMATION PROCESSING

20. Memory Memory refers to explicit recollection of information in the absenceof the original stimulus and to persisting effects of that informationon information processing that may be implicit. • EpisodicvsSemanticmemory • Declarativevsprocedural • sensory stores, short-term memory (workingmemory), and long-term memory

21. short-term memory (STM) • limited capacity • several seconds • 7 ± 2 memory spans • HCI: • distraction (18 sec) • STM load at complex HCI tasks

22. short-term memory, STM

23. long-term memory, LTM • shallow vs deep/semantic processing pl. searching for a link on a webpage • generation effect e.g. passwords • mnemonic techniques (ryhme, loci) • false memories

24. ATTENTION IN INFORMATION PROCESSING

25. Attention Attention is increased awareness directed at a particular eventor action to select it for increased processing. • result in enhanced understanding of the event, improvedperformance of an action, or better memory for the event • allows to filter out unnecessary information

26. Attention models • What happens with unattended stimuli? • filter-attenuation theory • early selection by filtering • attenuated signal may be sufficient • late-selection theory • stimuli are identified and later ignored • load theory • When memory load is high, it is not possible to suppress irrelevant information at a cognitive level

27. Attention and HCI • multi-task, different modality • change blindness • attentional blink • visual search • menu/icon • feature integration theory • attention demands decreaseas a task is practiced

28. Other cognitive areas in HCI • Task loading and stress • Emotions, mood, sentiment • Motivation and influencing • …

29. Summary • Cognitive models of human information processing • HCI can be effective if it is compatible with human information processing