6. Cognition

산업경영공학과

IMEN 315 인간공학

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



SELECTIVE ATTENTION 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

PERCEPTIONThree Perceptual Processes1. bottom-up feature analysis2. 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 inten-sity, unfamiliar accents)



3. 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 Perception4. maximize bottom-up processing5. maximize automaticity and unitization6. maximize top-down processing avoid confusion; use a smaller vocabulary; create context; exploit re-

dundancy

WORKING MEMORYA 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



Limits of Working MemoryCapacity Around 72 chunks of information (Miller, 1956) What makes a single chunk Familiarity based on past experience

(LTM), similar to unitization in perception1. Chunking reduces the number of items in WM, increasing the capacity

of working memory2. Chunking makes use of meaningful associations in LTM retention of

the information 3. Material more easily rehearsed, more likely to be transferred to LTM Perceptual chunks by spatial separationTime 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



Confusability and SimilarityAttention and Similarity WM is resource-limitedHuman Factors Implications of Working Memory Limits1. Minimize WM load2. Provide visual echoes3. Provide placeholders for sequential tasks4. 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

5. Minimize confusability6. Avoid unnecessary zeros in codes to be remembered7. Consider WM limits in istructions



LONG-TERM MEMORY Learning, training, retrieval, forgetting Semantic memory (memory for facts or procedures) or event memoryBasic MechanismStrength Frequency and recency of its useAssociationsWM and LTM Rote memory (rehearsal through simple repetition)Forgetting1. Weak strength due to low frequency and recency2. Weak or few associations with other information3. Interfering associations Recall, recognition



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 networkSchemas and Scripts Schema – the knowledge structure about a particular topic Scripts – schemas that a typical sequence of activitiesMental Models schemas about dynamic systems Generates a set of expectancies Population stereotypeCognitive Maps Mental representations of spatial information Mentally straightening Preferred or canonical orientation (mental rotation)



LTM Implications for Design1. Encourage regular use of info to increase frequency and recency2. Encourage active verbalization or reproduction of info that is to be re-

called3. Standardize4. Use memory aids Knowledge in the world vs. knowledge in the head5. Careful design info to be remembered6. 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 ac-

quired 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



Police lineup recognition – 20% incorrect at all 3 stages of encoding, storage, retrieval

Cognitive interview (CI) – not recognition but recall procedure



Prospective Memory for Future Events Failures of prospective memory are forgetting to do something in the fu-

ture – 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 performanceMeasuring SA SA global assessment technique (SAGAT) subjective awareness -- metacognition



Importance of SA to Human Factors1. designing easy-to-interpret displays of dynamic systems2. an important tool for accident analysis3. 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 solutionChallenges 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



an important top-down processing bias in troubleshooting – cognitive tunneling or confirmation bias

1. high system complexity2. 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



METACOGNITION AND EFFORT meta-knowledge or metacognition – people’s knowledge about their own

knowledge anticipated effort – seeking additional information related to selective at-

tention 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 allocationMental Effort and Resource Demand

the relationship between single-task difficulty and dial-task divided attention decrements -- resource theory

automaticity



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



Confusion similarity between items in WM; similarity-based confusion in visual sen-

sation; 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 “pro-

tected”? dual task performance (primary task vs. secondary task ) task man-

agement resource allocation successful time-sharing strategies – optimal switching of attention be-

tween tasks parallel processing vs. cognitive tunneling



Addressing Time-Sharing Overload1. Task redesign2. interface redesign3. training4. automation

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6. Cognition