1. INFORMATIN PROCESSING MODELS
6. Cognition
people perceive, think, and remember
three stages of human information processing system – perception, central processing or transforming, responding
INFORMATIN PROCESSING MODELS
top-down processing
learning retrieval

2. SELECTIVE ATTENTION PERCEPTION Three Perceptual Processes
not guarantee perception, but necessary to achieve it
four factors for the selection of channels to attend
salience: bottom-up process, attentional capture (blindness)
expectancy, value: top down processes
effort
PERCEPTION
Three Perceptual Processes
bottom-up feature analysis
unitization: sets of features familiar (represented in LTM), more rapid and automatic than perceptual processing
poor bottom-up processing: degradation of visual stimulus (short glance, tiny text, poor illumination) and auditory event (masking noise, low intensity, unfamiliar accents)

3. WORKING MEMORY Human Factors Guidelines in Perception
top-down processing: correct guess from expectations, based upon past experience in LTM; associations between the perceived stimulus and event (frequency and context)
Human Factors Guidelines in Perception
maximize bottom-up processing
maximize automaticity and unitization
maximize top-down processing
avoid confusion; use a smaller vocabulary; create context; exploit redundancy
WORKING MEMORY
A Model of Working Memory
Baddeley (1986, 1990) – central executive component
visuospatial sketch pad – analog spatial form while it is being used
phonological loop – verbal info in an acoustic form

4. Limits of Working Memory
Capacity
Around 7±2 chunks of information (Miller, 1956)
What makes a single chunk  Familiarity based on past experience (LTM), similar to unitization in perception
Chunking reduces the number of items in WM, increasing the capacity of working memory
Chunking makes use of meaningful associations in LTM  retention of the information
Material more easily rehearsed, more likely to be transferred to LTM
Perceptual chunks by spatial separation
Time
Maintenance rehearsal
Half life in WM (Card, Moran, Newell, 1986) – 7 sec for a memory store of three chunks and 70 secs for one chunk

5. Human Factors Implications of Working Memory Limits
Confusability and Similarity
Attention and Similarity
WM is resource-limited
Human Factors Implications of Working Memory Limits
Minimize WM load
Provide visual echoes
Provide placeholders for sequential tasks
Exploit chunking
Physical chunk size – 3 to 4 numbers or letters per chunk
Meaningful sequences
Superiority of letters over numbers
Keeping numbers separate from letters
Minimize confusability
Avoid unnecessary zeros in codes to be remembered
Consider WM limits in istructions

6. LONG-TERM MEMORY Basic Mechanism
Learning, training, retrieval, forgetting
Semantic memory (memory for facts or procedures) or event memory
Basic Mechanism
Strength
Frequency and recency of its use
Associations
WM and LTM
Rote memory (rehearsal through simple repetition)
Forgetting
Weak strength due to low frequency and recency
Weak or few associations with other information
Interfering associations
Recall, recognition

7. Organization of Info in LTM
Info in LTM in associative networks (semantic network)
The structure of the database compatible or congruent with the user’s semantic network
Schemas and Scripts
Schema – the knowledge structure about a particular topic
Scripts – schemas that a typical sequence of activities
Mental Models
schemas about dynamic systems
Generates a set of expectancies
Population stereotype
Cognitive Maps
Mental representations of spatial information
Mentally straightening
Preferred or canonical orientation (mental rotation)

8. LTM Implications for Design
Encourage regular use of info to increase frequency and recency
Encourage active verbalization or reproduction of info that is to be recalled
Standardize
Use memory aids
Knowledge in the world vs. knowledge in the head
Careful design info to be remembered
Design to support development of correct mental models
Visibility (affordance)
Episodic Memory for Events
The personal knowledge or memory of a specific event or episode is acquired from a single experience – very much based on visual imagery  not always faithful “video replays”, having a number of biases
Episodic memory process is far from perfect

9. Police lineup recognition – 20% incorrect at all 3 stages of encoding, storage, retrieval
Cognitive interview (CI) – not recognition but recall procedure

10. SITUATION AWARENESS Prospective Memory for Future Events Measuring SA
Failures of prospective memory are forgetting to do something in the future – sometimes called absentmindedness
Reminders, checklists
SITUATION AWARENESS
characterize user’s awareness of the meaning of dynamic changes in their environment
Endsley (1995) -- the perception of the elements in the environment within a volume of time and space, the comprehension of their meaning, and the projection of their status in the near future
SA is distinct from performance
Measuring SA
SA global assessment technique (SAGAT)
subjective awareness -- metacognition

11. PROBLEM SOLVING AND TROUBLESHOOTING
Importance of SA to Human Factors
designing easy-to-interpret displays of dynamic systems
an important tool for accident analysis
important for training
PROBLEM SOLVING AND TROUBLESHOOTING
troubleshooting a step within a problem-solving sequence
troubleshooting requires a series of tests to diagnose the problem while problem solving involves actions to implement the solution
Challenges
heavy cognitive activity, and human performance often limited
in troubleshooting, two or three active hypotheses in WM
troubleshooting closely depend upon appropriate cues and test outcomes  susceptible to attention and perceptual biases

12. PLANNING AND SCHEDULING
an important top-down processing bias in troubleshooting – cognitive tunneling or confirmation bias
high system complexity
intermittent failures of a given system component
PLANNING AND SCHEDULING
planning may be invoked in the absence of problem solving
in dynamic systems, predicted state and command (ideal) state
sluggish (higher inertia) systems – longer range planning
the importance to planning – level 3 SA, mental model (simulation)
predictive displays

13. METACOGNITION AND EFFORT
meta-knowledge or metacognition – people’s knowledge about their own knowledge
anticipated effort – seeking additional information related to selective attention is also related to another metacognition
ATTENTION AND TIME-SHARING
divide attention – do two or more things at one time
resource demand, structure, similarity, resource allocation
Mental Effort and Resource Demand
the relationship between single-task difficulty and dial-task divided attention decrements -- resource theory
automaticity

14. Structural Similarity
structural similarity – the similarity between key processing structures of both tasks in a concurrently performed pair
multiple resource theory (Navon & Gopher, 1979; Wickens, 1984, 2002) -- different structures in human information processing behave as if they were supported by multiple resources

15. Task Management and Interruptions
Confusion
similarity between items in WM; similarity-based confusion in visual sensation;
concurrent performance of two tasks that both have similar material
Task Management and Interruptions
if interference, then will they both suffer? Or will one or the other be “protected”?
dual task performance (primary task vs. secondary task )  task management  resource allocation
successful time-sharing strategies – optimal switching of attention between tasks  parallel processing vs. cognitive tunneling

16. Addressing Time-Sharing Overload
Task redesign
interface redesign
training
automation