고려대학교 산업공학과 IMS 621 Engineering Psychology Chapter 7. Memory and Training ...

고려대학교 산업공학과

IMS 621 Engineering Psychology

Chapter 7. Memory and Training

OVERVIEW Working memory – temporary, attention-demanding store to retain new info until we use

it examine, evaluate, transform, compare, mental

arithmetic, predict hold new info until encoding it into long –term

memory Long-term memory – storehouse of facts about the world and how to do things memory – three stage presentation (fig 7.1)

encoding – the process of putting things into memory system storage – the way in which information is held or represented in the two memory

systems retrieval – our ability to access information in memory (forgetting)



WORKING MEMORY three core components (fig 6.5)

verbal component phonological store – info in linguistic form, words and sounds articulatory loop – rehearsed by articulating words and sounds

spatial component – visuospatial sketchpad info in an analog, spatial form, often typical of visual images stores info in a particular form, or code

central executive – controls WM activity and assigns attentional resources to subsystems Code Interference

verbal-phonetic and visual-spatial codes function cooperatively than competitively Brooks (1968) -- tasks should be designed so that the disruption by different concurrent

activities does not occur (the greater resource competition with spatial working memory in the spatial response condition produced greater interference and vice versa)

Interference in the Central Executive four core functions of the central executive (Baddeley, 1996)

1) to coordinate performance on multiple tasks2) to temporarily hold and manipulate information stored in LTM3) to change retrieval strategies from LTM4) to attend selectively to stimuli



a task demanding central executive resources should not be performed concurrently with other tasks drawing on those resources

Matching Display with Working Memory Code principle of stimulus/central-processing/response compatibility – best association of display

formats to codes of working memory S – display modality (auditory and visual) C – two possible central-processing codes (verbal and spatial) R – two possible response modalities (manual and vocal)

S-C compatibility (fig 7.3) Limitations of Working Memory: Duration and Capacity Duration

how long does information in WM last if it is not rehearsed? Brown-Peterson paradigm – decay function (fig 7.4)

without continuous rehearsal, little info is retained beyond 10 to 15 seconds transience applied to both spatial and verbal working memory

augment the initial transient stimulus with a long-lasting visual display – memory aid Capacity and Chunking

capacity limit interacts with time (fig 7.4) – the faster the rehearsal speed, the larger the capacity memory span – the limiting number recalled with full attention

max. capacity of WM -- 7± 2 chunks of information chunk – a set of adjacent stimulus units tied together by associations in the LTM



chunking – recording info. by semantically associating low-level elements (letters better than digits) chunking may be facilitated by parsing (physically separating likely chunks) optimum chunk size – three to four for arbitrary alphanumeric strings

Interference and Confusion MTBR lost from WM through interference from info learned at another time (fig 7.5) PI (proactive interference) – activity engaged in prior to encoding the MTBR disrupts its retrieval

pronounced, especially in a series of memory tasks with little time between them RI (retroactive interference) – activity during the retention interval disrupts retrieval of the MTBR items in WM sometimes forgotten because they are confused with items held in the same time confusion – similarity -- typically acoustic but sometimes semantic to minimize memory interference and confusion

1) avoid creating large strings of similar sounding chunks2) use different codes (verbal vs. spatial) for different sources of information3) use digit strings that are particularly easy to remember4) ensure that the intervals before, during, and after storage are free of unnecessary activity

using the same code (spatial or verbal) as the stored info Running Memory

A sequence of stimuli is presented to the operator, who neither knows its length nor is expected to retain the entire sequence. Instead, a different response must be made to each stimulus or series of stimuli at some lag after they occur. – memory span less than 7±2



EXPERTISE AND MEMORY Expertise

domain specific – advantages in a specified domain1. acquired through practice or training in a domain2. provides a measuring performance advantage3. involve specialized, rather than generic, knowledge a task that defines the domain of expertise is called intrinsic a task that is not central to the domain of expertise, but greater expertise in the domain improves

performance nonetheless, is called contrived Expertise and Chunking

chunking strategies can be acquired through expertise store relevant stimulus material in WM in terms of chunks rather than lowest-level unit our ability to chunk information depends on our expertise in the subject domain

Skilled Memory two aspects of performance in skilled tasks that are difficult for traditional view of WM1. skilled activities can be interrupted, and later resumed, with little effect on performance <-> transient2. performance in skilled tasks requires quick access to a large amount of info <-> limited capacity Ericsson and Kintsch (1995) – WM includes another mechanism based on skilled use of storage in

LTM – long-term working memory (LT-WM) info. in LT-WM is stable, but accessed through temporarily active retrieval cues in WM



domain specific skills allow LT-WM for the skilled activity (medical diagnosis, waiting tables, mental arithmetic)

expert chess player -- retrieval structure (a set of retrieval cues) stored in WM to access the info stored in LT-WM

chunking is thought of as a particular kind of retrieval structure PLANNING AND PROBLEM SLOVING

a plan can be defined as a strategy for solving a problem planning and problem solving occur in the central executive planning difficulty increases when there are more choices available for action (fewer constraints) satisficing heuristic – selects the current best plan with no guarantee that it is the absolute best implementation cost – the cost associated with performing the actions resulting from a particular

plan the amount of time required opportunistic planning -- the problem solving occurs by following the most promising leads at any

point in time – can lead to solutions bit are not optimal – locally optimal but globally suboptimal automated planning system – useful with multiple solutions but decreases exploratory behavior

and lead to deterministic interpretation of presented info SITUATION AWARENESS

situation awareness resides in WM (experts in LT-WM) relatively domain specific SA has important application for design

1. it has implications for display design2. it has implications for automation



LEARNING AND TRAINING Development of Expertise: Learning

two general cognitive models to explain learning: ACT-R and Soar ACT-R – production system model

currently active information is compared to a set of production rules (IF-THEN statements)

Procedural knowledge – knowledge of how to do things (knowing how) declarative knowledge – knowledge of facts (knowing what) – chunks production rules embody procedural knowledge, but their conditions and actions are defined in

terms of declarative knowledge in terms of chunks formation of production rules is a key part of learning emphasis on practice on specific example to improve learning in the ACT-R framework Soar – a general cognitive architecture relying on production rules Soar does not distinguish between declarative and procedural knowledge Soar learns the particular response that must be made, and stores that as a chunk common characteristics of ACR-T and Soar of how cognitive learning occur

1. emphasis on instances2. recall of the instance through chunking3. recall strategies for training and experience4. novices for open-ended strategies such as means-end analysis5. intelligent tutors based on ACT-R that teach cognitive skills



Transfer of Training training efficiency

1) the best learning in the shortest time2) longest retention3) is cheapest?

transfer of training how much a new skill can capitalize what has been learned before?

Measuring Transfer positive, zero, negative transfer (fig 7.7) % transfer = (control time – transfer time)/(control time) x 100 = savings/(control time) x 100 transfer effectiveness ratio

TER = (amount of savings)/(transfer group time in training program) x 100 training cost ratio

TCR = training cost in target environment (per unit time) training cost in the training program (per unit time)

if TER x TCR > 1, then the program is cost effective -- (if not, consider safety considerations) Training System Fidelity maximum positive transfer if all elements of a task were identical to the target task (fig 7.8)1. expensive , added realism not necessarily add to their TER2. high similarity may be detrimental by leading incompatible response tendencies/strategies3. complexity – increase workload



instead of total fidelity, which components of training similar to the target task critical task components, processing demands, or task-relevant perceptual consistency

Virtual Environments cost effective method for training tradeoff between TER and TCR -- lowering TER but increasing TCR more effective training technique for navigation of space Negative Transfer negative transfer is related to stages of processing (table 7.1) the lack of standardization in the control arrangements

Training Techniques Practice and Overlearning “practice makes perfect “ but how much practice after zero performance errors

the speed of performance increases at a rate proportional to the log of the # of trials attention or resource demand decreases – automated fashion

overlearning decreases the rate of forgetting of the skill Elaborative Rehearsal rehearsal is an active process, necessary to maintain chunks of info in WM maintenance rehearsal – good way to maintain info. in WM but ineffective for transferring to LTM elaborative rehearsal – the meaning of the material, chunking, result from active learning situation,

demand working-memory resources interfere with learning



Reducing Cognitive Load cognitive load theory – the effects of high demands on working memory on training

effectiveness diagram, proximity-compatibility principle, dual modality presentation, worked sample Part-Task Training segmentation – useful when segments of the skill vary greatly in their difficulty (fig 7.9) fractionization – separate practice on two or more components

allows attention to be focused on each component, reducing cognitive load and allowing automatic processing to develop

separating task components prevents the development of time-sharing skills effective with independently broken off components and learnable consistencies effective if task components draw on different WM subsystems Guided Training error prevention training wheels approach – offers explicit and immediate feedback about the error errors should not be eliminated completely – long-term learning impaired Knowledge of Results (KR) feedback about the quality of performance, useful for motivation and performance1) delayed KR and the interval with other activities – performance declined through RI2) KR during performance less well than after completion – divided attention



Learning by Example case studies – annotations and elaboration not excessive cognitive load processing example Consistency of Mapping between target info. and the trainee’s response varied mapping increases in performance during training search for various targets in various contexts, feature learning procedure between

consistent and varied mapping LTM

Knowledge Representation procedural and declarative knowledge, semantic and episodic memory Knowledge Organization information is not stored in a random collection of facts, rather in structure and organization system features are congruent with the operator’s organization of that knowledge Methods for Representing Long-Term Knowledge organization of an expert user’s knowledge – useful for training program, improving the

design of an interface, or building a menu/index structure multiple knowledge acquisition techniques

scaling technique – gives a sense of how domain concepts are related to each other, usually by having experts rate pairs of concepts

protocol technique – perform typical tasks and think aloud interviews, observation, and document analysis



conceptual graph analysis – a representation of a user’s knowledge of a system (fig 7.10) Mental Models a mental structure that reflects the user’s understanding of a system – may be created

spontaneously by the user or carefully formed and structured though training incorporating a mental model into a training program can be effective -- visibility

Memory Retrieval and Forgetting Recall and Recognition recall – knowledge in the head recognition – knowledge in the world (yes or no response or a choice response) – more

sensitive failure of recall and recognition (forgetting)

RI, PI, similarity (confusion), the absence of retrieval cues, passage of time (recency) one particular kind of recall related to remembering to do something – prospective memory –

checklists Skill Retention

Degree of Overlearning additional practice after performance reaches error free -- automation Skill Type perceptual-motor skill – very little forgetting over long time procedural skill – more rapidly forgotten Individual Differences fast learners better retention than slow learner – chunking skills

고려대학교 산업공학과 IMS 621 Engineering Psychology Chapter 7. Memory and Training ...

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