cognitive work. cognitive engineering improving the effectiveness, efficiency and safety of tasks...

Cognitive WorkCognitive Work

Cognitive EngineeringCognitive Engineering

Improving the effectiveness, efficiency and Improving the effectiveness, efficiency and safety of tasks performed primarily in the safety of tasks performed primarily in the mind (e.g. decision making, planning, mind (e.g. decision making, planning, design, etc.)design, etc.)If we are to do so, we must first If we are to do so, we must first understand:understand:– InformationInformation– Human information processing (capabilities Human information processing (capabilities

and limitations)and limitations)


““Thinking” work; planning, design, Thinking” work; planning, design, diagnosis, management.diagnosis, management.

Cognitive work is not traditionally included Cognitive work is not traditionally included in methods engineering and work design,in methods engineering and work design,

However, much work available today However, much work available today involves both involves both cognitivecognitive and and physicalphysical components.components.


What jobs involve a large component of What jobs involve a large component of cognitive work? cognitive work?

Secretary, air traffic controller, doctor, taxi driver, Secretary, air traffic controller, doctor, taxi driver, chess player, …chess player, …

Which components are cognitive and which Which components are cognitive and which physical?physical?

Search and rescue, soccer, military field work.Search and rescue, soccer, military field work.

Cognitive performance is tied to physical activity Cognitive performance is tied to physical activity level.level.




Which jobs are Which jobs are bothboth cognitive and physical? cognitive and physical?

Search and rescue, soccer, military field work.Search and rescue, soccer, military field work.





Which jobs are Which jobs are bothboth cognitive and physical? cognitive and physical?

Driving,Driving, ssearch and rescue, soccer, military field earch and rescue, soccer, military field work.work.


Cognitive EngineeringCognitive Engineering

(Re)design the(Re)design the– toolstools, , – work work process, or process, or – work work

environmentenvironment

to improve to improve effectiveness in effectiveness in cognitivecognitive work work

Tools(Products)

Work Process

Work environmen

t

Organizationalstructure

Motivation:Incentives/rewards

InformationInformation

Cybernetics:Cybernetics: the study of information. the study of information. Started in 1940’s and 1950’s.Started in 1940’s and 1950’s.

Bits:Bits: a measure of Information: one bit can a measure of Information: one bit can represent two alternatives: 1 or 0.represent two alternatives: 1 or 0.

H bits can represent n = 2H bits can represent n = 2HH alternatives; alternatives;

H = logH = log2 2 n (n = number of alternatives).n (n = number of alternatives).

ExampleExample

How many bits are needed to represent the 26 How many bits are needed to represent the 26 letters of the alphabet? letters of the alphabet?

They can be represented with 5 bitsThey can be represented with 5 bits

H bits = logH bits = log22 26 alternatives 26 alternatives = 4.7= 4.7 (round up to next integer, 5)(round up to next integer, 5)

Therefore it takes at least Therefore it takes at least 5 bits5 bits to represent the 26 to represent the 26 letters in the alphabet.letters in the alphabet.

(ASCII codes use 7 bits to represent letters, numbers (ASCII codes use 7 bits to represent letters, numbers and symbols).and symbols).

If we use 5 bits for each letter, the word If we use 5 bits for each letter, the word “panda”“panda” can be represented with: can be represented with:

5 letters x 5 bits/letter = 25 bits.5 letters x 5 bits/letter = 25 bits.

Information PropertiesInformation Properties

Bandwidth:Bandwidth: bits/second that can be bits/second that can be transferred through a communication transferred through a communication channel. channel.

There is much There is much redundancyredundancy in written in written letters (66%), spoken language, and letters (66%), spoken language, and communication systems in general. communication systems in general.

Redundancy can be important for Redundancy can be important for error error correction. correction.

Human Information ProcessingHuman Information ProcessingMemory: 3 typesMemory: 3 types

Sensory StoreSensory Store

Short Term Memory (STM) or “working Short Term Memory (STM) or “working memory”memory”

Long Term Memory (LTM)Long Term Memory (LTM)

Good review of memory in: Good review of memory in: The Complete The Complete Problem SolverProblem Solver, by J. R. Hayes, 1981, Chapter , by J. R. Hayes, 1981, Chapter Four: “The Structure of Human Memory”.Four: “The Structure of Human Memory”.

Human Information Processing ModelHuman Information Processing Model MemoryMemory

Human Information ProcessingHuman Information Processing3 Stages:3 Stages:

PerceptionPerceptionDecision and Response SelectionDecision and Response SelectionResponse ExecutionResponse Execution

The dividing line between them is not necessarily The dividing line between them is not necessarily distinct.distinct.

Attention ResourcesAttention Resources focus our perception, focus our perception, decisions and actions.decisions and actions.

We will examine memory and information processing We will examine memory and information processing as it progresses from inputs to outputs.as it progresses from inputs to outputs.

Human Information Processing Model:Human Information Processing Model:3 Stages of Information Processing3 Stages of Information Processing

Human Information Processing Model:Human Information Processing Model:Sensory Store (very short term)Sensory Store (very short term)

Sensory Stores: Sensory Stores: Very short term memory for sensory Very short term memory for sensory

informationinformation

One sensory store associated with each One sensory store associated with each sensory input channel (vision, hearing, …)sensory input channel (vision, hearing, …)

Decay of information is Decay of information is veryvery rapid, rapid,

Information gone in 1 – 2 seconds.Information gone in 1 – 2 seconds.

Human Information Processing ModelHuman Information Processing Model PerceptionPerception

PerceptionPerception

Perception:Perception: categorization of incoming categorization of incoming stimuli stimuli (Neibel and Freivalds).(Neibel and Freivalds).

– DetectionDetection (simplest form) (simplest form)Decide “Is signal present or not present?” Decide “Is signal present or not present?”

Example: peripheral vision test: raise hand when you Example: peripheral vision test: raise hand when you see a white dot appear.see a white dot appear.

– Classification:Classification: determine the category in which a determine the category in which a stimulus belongs. E.g. “Red dot or white dot?”stimulus belongs. E.g. “Red dot or white dot?”

– Scene analysisScene analysis: understand a complex image.: understand a complex image.

Short Term Memory (STM)Short Term Memory (STM)

Items in current focus of attention,Items in current focus of attention,

Holds 7 Holds 7 +/- +/- 2 “chunks,”2 “chunks,”

Half life of 3 items is about 7 seconds,Half life of 3 items is about 7 seconds,

All items gone in 18 seconds.All items gone in 18 seconds.

Information Theory and the BrainInformation Theory and the Brain

During the 1950’s attention to cybernetics During the 1950’s attention to cybernetics raised the question in the minds of raised the question in the minds of psychologists: psychologists:

““How much information can human How much information can human memory hold?”memory hold?”

George Miller (1956) attempted to answer George Miller (1956) attempted to answer this question for short term memory this question for short term memory (STM).(STM).

Information Capacity of STMInformation Capacity of STM

ProblemProblem: the amount of information that can be : the amount of information that can be stored in short term memory depends on what a stored in short term memory depends on what a person person knowsknows about those items. about those items.

People can remember in STM:People can remember in STM:– Many familiar concepts,Many familiar concepts,– Few unfamiliar concepts.Few unfamiliar concepts.

Example: can you remember this sentence?Example: can you remember this sentence?

““Wir kann mit Zug zu Euch kommenWir kann mit Zug zu Euch kommen.” (155 bits).” (155 bits)

Information Capacity of STMInformation Capacity of STM

ProblemProblem: the number of items that can be stored : the number of items that can be stored in short term memory depends on what a person in short term memory depends on what a person knowsknows about those items. about those items.

People can remember in STM:People can remember in STM:– Many familiar concepts,Many familiar concepts,– Few unfamiliar concepts.Few unfamiliar concepts.

Example: can you remember this sentence?Example: can you remember this sentence?

““Wir kann mit Zug zu Euch kommenWir kann mit Zug zu Euch kommen.” (125 bits).” (125 bits)

““We can take the train to your placeWe can take the train to your place.”.”

ChunksChunks

ChunkChunk: a package of information that is : a package of information that is treated as a unit treated as a unit (Hayes, J. R., 1981).(Hayes, J. R., 1981).

Miller (1956) proposed “chunks” as the Miller (1956) proposed “chunks” as the units stored in memory. units stored in memory.

Chunks do not measure information, per Chunks do not measure information, per se. They are collections of knowledge.se. They are collections of knowledge.

ChunksChunks

A chunk can reference (e.g. point to) a A chunk can reference (e.g. point to) a large body of knowledge in long-term large body of knowledge in long-term memory.memory.Example:Example:– A year and a half ago “Palin” may have meant A year and a half ago “Palin” may have meant

little to you.little to you.– This week “Palin” may be linked to complex This week “Palin” may be linked to complex

set of concepts: politics, Alaska, hunting, set of concepts: politics, Alaska, hunting, hockey, …hockey, …

Long Term Memory (LTM)Long Term Memory (LTM)

Information can potentially stay in LTM a lifetime.Information can potentially stay in LTM a lifetime.

With out rehearsal, information in LTM tends to With out rehearsal, information in LTM tends to decay exponentially, biggest loss in first few days.decay exponentially, biggest loss in first few days.

One can have information in LTM, but be unable One can have information in LTM, but be unable to get at it (tip-of-tongue phenomena) to get at it (tip-of-tongue phenomena) (Brown and (Brown and McNeil, 1996)McNeil, 1996)

Information can be transferred from STM to LTM Information can be transferred from STM to LTM through a) rehearsal, b) association with concepts through a) rehearsal, b) association with concepts already in STM.already in STM.

Human Information Processing ModelHuman Information Processing Model (Sanders and MCormick, 1993)(Sanders and MCormick, 1993)

Examples of STM => LTMExamples of STM => LTM

Rehearsal: Rehearsal: – Repeat telephone number or social security Repeat telephone number or social security

number until you remember it,number until you remember it,– Practice piano piece till you memorize it.Practice piano piece till you memorize it.

Association with existing knowledge in LTM:Association with existing knowledge in LTM:– Lady introducing herself at a party: “Hi, I’m Lady introducing herself at a party: “Hi, I’m

Marsha Hoover – like the vacuum cleaner.”Marsha Hoover – like the vacuum cleaner.”– Method of Loci: Associate items to be Method of Loci: Associate items to be

remembered with items on a path through your remembered with items on a path through your house [house [described in [Hayes, J. R., 1981] pp. 98 – 104).described in [Hayes, J. R., 1981] pp. 98 – 104).

Method of LociMethod of Loci

Associate a list of items with a list of Associate a list of items with a list of “stops” on a route through your house.“stops” on a route through your house.

Associate first item with first “stop,” second Associate first item with first “stop,” second item with second stop, etc.item with second stop, etc.

Picture item interacting with something at Picture item interacting with something at its “stop.”its “stop.”

To retrieve the list, “walk” the route To retrieve the list, “walk” the route through your house in your mind.through your house in your mind.

AttentionAttention

AttentionAttentionAttentionAttention: cognitive : cognitive capacity devoted to a capacity devoted to a task (Neibel and task (Neibel and Frievalds).Frievalds).Attention is largely a Attention is largely a serialserial processprocessMulti-tasking:Multi-tasking: If we try to If we try to attend to attend to multiple tasksmultiple tasks performance typically performance typically goes goes downdown. Wickens’ . Wickens’ (1984) multiple resource (1984) multiple resource theory predicts/explains theory predicts/explains performance decrement.performance decrement.

AttentionAttention

Operator Vigilance: Operator Vigilance: sustained attention, sustained attention, ability to remain alert over a long period of ability to remain alert over a long period of time.time.Vigilance tends to go down after 30 min or Vigilance tends to go down after 30 min or so.so.Important in monitoring and inspection:Important in monitoring and inspection:– Truck driving, flying,Truck driving, flying,– Nuclear power plant monitoring,Nuclear power plant monitoring,– Visual inspection ..Visual inspection ..

Human Information Processing ModelHuman Information Processing Model

Decision Making Decision Making and Response Selectionand Response Selection

Decision makingDecision making: the process of considering alternatives, : the process of considering alternatives, and choosing and appropriate response.and choosing and appropriate response.Decision making may take:Decision making may take:– Seconds: what to do when a deer jumps in front of your car).Seconds: what to do when a deer jumps in front of your car).– Minutes: what new route should an airplane take around a Minutes: what new route should an airplane take around a

thunderstorm? Emergency room triage.thunderstorm? Emergency room triage.– Days (or longer): what launch plan should we follow for the next Days (or longer): what launch plan should we follow for the next

space mission?space mission?

Perception, decision making and response selection are Perception, decision making and response selection are not always easily separable.not always easily separable. Decision making may be undertaken by Decision making may be undertaken by individualsindividuals or or groupsgroups..

Some observed challenges in Some observed challenges in human decision makinghuman decision making

People tend to focus on only one People tend to focus on only one alternative or hypothesis at a time – once alternative or hypothesis at a time – once selected others are often ignored.selected others are often ignored.

Undue weight given to early cues, later Undue weight given to early cues, later ones often ignored.ones often ignored.

More information (even if relevant) can More information (even if relevant) can reduce decision making effectiveness reduce decision making effectiveness ((information overloadinformation overload).).

More decision making challengesMore decision making challenges

People are:People are:

Not good at exhaustive exploration of a Not good at exhaustive exploration of a problem space, or remembering what has problem space, or remembering what has been explored and what has not.been explored and what has not.

Not great at working with uncertainty.Not great at working with uncertainty.

Variables with unknown values are often Variables with unknown values are often ignored.ignored.

Information Processing Speed Information Processing Speed in Simple Decision Makingin Simple Decision Making

Multiple factors effect decision making and Multiple factors effect decision making and response speed: response speed: – Number of alternatives (Hick-Hyman Law)Number of alternatives (Hick-Hyman Law)– Spatial properties of alternatives (Fits’ Law)Spatial properties of alternatives (Fits’ Law)– Length of practice with task or problem Length of practice with task or problem

solving method (Power Law of Practice)solving method (Power Law of Practice)

cognitive work. cognitive engineering improving the effectiveness, efficiency and safety of tasks...

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