1. Chapter 2 Human Information Processing

2. HCI as a system
human
computer

3. Cognitive process

4. Human information processing

5. STUDYING HUMAN INFORMATION 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’s radar signals after 30 minutes in a radar observation shift)

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

8. Reaction Time (RT) series of discrete processing stages
Additive factors method
two variables that affect different stages should have additive effects on RT while two variables that affect the same stage should have interactive effects on RT
e.g. mode of icon array (menu or dialog box), number of icons, and difficulty of movement had additive effects on response times

9. RT vs. accuracy

10. Neuroergonomics
electroencephalograms (EEG) fMRI

11. INFORMATION PROCESSING IN CHOICE REACTION TASKS

13. Mental rotation R R

14. Response Selection RIGHT LEFT
Hick-Hyman law (N equally likely alternatives):
Compatibility effects
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 different at various devices)
W is target width
other factors, 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
based on interaction, the user develops a representation of how the system is functioning for a given task
metaphors
real life (e.g. desktop)
other tasks/systems (e.g. web browsers)
human decision-making heuristics
(when the outcome associated with a choice is uncertain)
e.g. anchoring heuristic involves making a judgment regarding probabilities of alternative states based on initial information

19. HUMAN MEMORY IN INFORMATION PROCESSING

20. Memory
Memory refers to explicit recollection of information in the absence of the original stimulus and to persisting effects of that information on information processing that may be implicit.
Episodic vs Semantic memory
Declarative vs procedural
sensory stores, short-term memory (working memory), 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 event or action to select it for increased processing.
result in enhanced understanding of the event, improved performance 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 decrease as 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