How Experts Differ from Novices Melissa Eubank. How Experts Differ form Novices When it comes to problem solving, experts have gained a lot of knowledge

How Experts Differ from How Experts Differ from NovicesNovices

Melissa EubankMelissa Eubank

How Experts Differ form NovicesHow Experts Differ form Novices

When it comes to problem solving, experts When it comes to problem solving, experts have gained a lot of knowledge that affects have gained a lot of knowledge that affects what they notice.what they notice.

This knowledge also affects how they This knowledge also affects how they organize, represent, and interpret organize, represent, and interpret information.information.

How Experts Differ from NovicesHow Experts Differ from Novices

6 Principles of Expertise6 Principles of Expertise Meaningful Patterns of informationMeaningful Patterns of information Organization of KnowledgeOrganization of Knowledge Context and Access to KnowledgeContext and Access to Knowledge Fluent RetrievalFluent Retrieval Experts and TeachingExperts and Teaching Adaptive ExpertiseAdaptive Expertise

Meaningful Patterns of InformationMeaningful Patterns of Information

““Experts notice features and meaningful patterns Experts notice features and meaningful patterns of information that are not noticed by novices.”of information that are not noticed by novices.”

Experience is KeyExperience is Key Chunking Chunking Examples:Examples:

ChessChess Electronics TechniciansElectronics Technicians PhysicistsPhysicists TeachersTeachers


ExperienceExperience Experts have seen the problem before, Experts have seen the problem before,

therefore they can see patterns of meaningful therefore they can see patterns of meaningful information.information.

The problem is not really a “problem”.The problem is not really a “problem”. Because they can see the patterns of Because they can see the patterns of

meaningful information experts problem meaningful information experts problem solving starts at a “higher level”.solving starts at a “higher level”.


ChunkingChunking Put together information into familiar patterns.Put together information into familiar patterns. Chunking enhances short term memory.Chunking enhances short term memory.

• Example:Example: 0111000111010010101110001110100101


Chess: Masters vs. Lesser ranked chess Chess: Masters vs. Lesser ranked chess players.players. Chess masters were able to out play their opponents Chess masters were able to out play their opponents

because if the knowledge they acquired from hours because if the knowledge they acquired from hours upon hours of playing chess.upon hours of playing chess.

Chess masters experiences lead to recognition of Chess masters experiences lead to recognition of meaningful chess configurations (using chunking) meaningful chess configurations (using chunking) which leads to the realization of the best strategy with which leads to the realization of the best strategy with the most superior moves to win based on these the most superior moves to win based on these configurations.configurations.

Chess masters can chunk together chess pieces in a Chess masters can chunk together chess pieces in a configuration.configuration.


Electronics Technicians.Electronics Technicians. Expert electronics technicians were able to Expert electronics technicians were able to

reproduce large portions of complex circuit reproduce large portions of complex circuit diagrams after only a few SECONDS of diagrams after only a few SECONDS of viewing. viewing.

Chunked several individual circuit elements Chunked several individual circuit elements that performed the function of an amplifier. that performed the function of an amplifier.

Novices could not do this.Novices could not do this. Being a novice in this area I hardly Being a novice in this area I hardly

understand the words!!understand the words!!


Physicists Physicists Mathematical ExpertsMathematical Experts Recognize problems of river currents and Recognize problems of river currents and

problems of headwinds and tailwinds in problems of headwinds and tailwinds in airplanes to all involve relative velocities.airplanes to all involve relative velocities.

They chunked all of these into relative velocity They chunked all of these into relative velocity problems. Only an expert physicist would be problems. Only an expert physicist would be able to do that with expert mathematical skills able to do that with expert mathematical skills would be able to do that.would be able to do that.


TeachersTeachers Expert and Novice teachers were shown a videotaped Expert and Novice teachers were shown a videotaped

classroom lesson and asked to talk about what they classroom lesson and asked to talk about what they were seeing.were seeing.

Expert teachers noticed:Expert teachers noticed:• Note-taking strategies of students.Note-taking strategies of students.• Students loosing interest in the lesson.Students loosing interest in the lesson.• That the students seem to be accelerated learners.That the students seem to be accelerated learners.

Novice teachers:Novice teachers:• Couldn’t tell what students were doing.Couldn’t tell what students were doing.• Couldn’t understand what was going on.Couldn’t understand what was going on.• Said “It’s a lot to watch.”Said “It’s a lot to watch.”

Organization of KnowledgeOrganization of Knowledge ““Experts have acquired a great deal of content Experts have acquired a great deal of content

knowledge that is organized in ways that reflect knowledge that is organized in ways that reflect a deep understanding of their subject matter.”a deep understanding of their subject matter.”

Big Ideas guide expert thinking.Big Ideas guide expert thinking. Experts Experts understandunderstand the problem vs. novices who the problem vs. novices who

just want to solve the problem.just want to solve the problem. Examples:Examples:

PhysicsPhysics MathematicsMathematics Adults and ChildrenAdults and Children

Organization of KnowledgeOrganization of Knowledge

““Big Ideas”Big Ideas” Experts knowledge is organized around core Experts knowledge is organized around core

concepts that guide their thinking about their concepts that guide their thinking about their domains.domains.

Novices are more likely to approach problems Novices are more likely to approach problems by searching for the correct formulas. Their by searching for the correct formulas. Their knowledge is simply a list of facts and knowledge is simply a list of facts and formulas that are relevant to the domain.formulas that are relevant to the domain.


Understanding the problem.Understanding the problem. Experts want to understand what the problem Experts want to understand what the problem

means rather than just plug in numbers in a means rather than just plug in numbers in a formula to get an answer.formula to get an answer.

By understanding the problem experts can By understanding the problem experts can then explain why they used the tactics they then explain why they used the tactics they did to solve the problem.did to solve the problem.

Organization of KnowledgeOrganization of Knowledge PhysicsPhysics

Experts:Experts:• Use the core concept if Newton’s 2Use the core concept if Newton’s 2ndnd Law. The sum of the Law. The sum of the

external forces equals the mass multiplied by the external forces equals the mass multiplied by the acceleration. F=Ma. acceleration. F=Ma.

• Draw Free Body Diagrams in order to see all the external Draw Free Body Diagrams in order to see all the external forces and get a generic formula for solving the problem.forces and get a generic formula for solving the problem.

• When looking at different problems experts group these When looking at different problems experts group these problems based on the major principle that could be applied problems based on the major principle that could be applied to solve.to solve.

Novices:Novices:• Immediately plug in numbers into formulas.Immediately plug in numbers into formulas.• Memorize, recall and manipulate to get answers they need.Memorize, recall and manipulate to get answers they need.• Grouped problems together based on if the pictures looked Grouped problems together based on if the pictures looked

similar. similar.


MathematicsMathematics Experts want to understand the problem and Experts want to understand the problem and

not just plug in numbers like novices.not just plug in numbers like novices. Experts and Novices were asked to solve an Experts and Novices were asked to solve an

algebra word problem that is logically algebra word problem that is logically impossible. impossible. • Experts wanting to understand the problem quickly Experts wanting to understand the problem quickly

realized that it was logically impossiblerealized that it was logically impossible• Novices used the numbers in the problem to plug Novices used the numbers in the problem to plug

into equations that they would use to solve it, into equations that they would use to solve it, getting an unrealistic answer.getting an unrealistic answer.


Adults (Experts) vs. Children (Novices)Adults (Experts) vs. Children (Novices) Adults and children were asked:Adults and children were asked:

There are 26 sheep and 10 goats on a ship. There are 26 sheep and 10 goats on a ship. How old is the captain?How old is the captain?• Adults had enough expertise to realize that you do Adults had enough expertise to realize that you do

not have enough information to solve this problem.not have enough information to solve this problem.• Children attempted to answer this question with a Children attempted to answer this question with a

number by adding, subtracting, etc. They did not number by adding, subtracting, etc. They did not try to understand the problem.try to understand the problem.

Context and Access to KnowledgeContext and Access to Knowledge

““Experts’ knowledge cannot be reduced to isolated facts Experts’ knowledge cannot be reduced to isolated facts or propositions but, instead, reflects contexts of or propositions but, instead, reflects contexts of applicability: that is, the knowledge is “conditionalized” applicability: that is, the knowledge is “conditionalized” on a set of circumstances.”on a set of circumstances.”

Retrieving relevant knowledgeRetrieving relevant knowledge ““Conditionalized”Conditionalized” Examples:Examples:

TextbooksTextbooks Word ProblemsWord Problems TestsTests


Retrieving relevant knowledge.Retrieving relevant knowledge. Experts know A LOT. But when they need to Experts know A LOT. But when they need to

solve a certain problem they don’t need all of solve a certain problem they don’t need all of the information they know.the information they know.

Experts do not search through all the Experts do not search through all the knowledge they know. This would be knowledge they know. This would be overwhelming. Experts selectively retrieve overwhelming. Experts selectively retrieve the relevant information they need. the relevant information they need.

Experts are GOOD at retrieving the relevant Experts are GOOD at retrieving the relevant knowledge they need to solve a problem.knowledge they need to solve a problem.


Conditionalized KnowledgeConditionalized Knowledge ““Conditionalized”- Knowledge includes a Conditionalized”- Knowledge includes a

specification of the contexts in which it is specification of the contexts in which it is useful.useful.• In other words, experts know when their In other words, experts know when their

knowledge is useful.knowledge is useful. Knowledge must be conditionalized in order to Knowledge must be conditionalized in order to

be retrieved when it is needed.be retrieved when it is needed.• Have to know when your knowledge is useful in Have to know when your knowledge is useful in

order to retrieve that knowledge when it is needed order to retrieve that knowledge when it is needed to solve a problem.to solve a problem.


TextbooksTextbooks DO NOT help students to conditionalize their DO NOT help students to conditionalize their

knowledge. They teach laws of mathematics knowledge. They teach laws of mathematics but not when these laws are useful for but not when these laws are useful for problem solving. problem solving. • Students have to learn when their knowledge is Students have to learn when their knowledge is

useful all on their own.useful all on their own. Present facts and formulas, but not the Present facts and formulas, but not the

conditions in which these facts and formulas conditions in which these facts and formulas are useful.are useful.


Word ProblemsWord Problems Word problems that use the appropriate facts and Word problems that use the appropriate facts and

formulas help students to know when, where and why formulas help students to know when, where and why to use the knowledge they are learning.to use the knowledge they are learning.

Example: Addition and Subtraction.Example: Addition and Subtraction.• If you have 2 apples and your friend Julie gives you 7 more If you have 2 apples and your friend Julie gives you 7 more

but then Charlie eats 3 of your apples. How many apples do but then Charlie eats 3 of your apples. How many apples do you have?you have?

• Children might know how to add and subtract numbers but Children might know how to add and subtract numbers but the word problem will help them to know when their the word problem will help them to know when their knowledge is useful.knowledge is useful.


TestsTests Many ask for only facts and not when, where or why Many ask for only facts and not when, where or why

to use those facts.to use those facts. Some tests have questions that are in order of how Some tests have questions that are in order of how

students learned them from the book.students learned them from the book.• Therefore students think that they have conditionalized their Therefore students think that they have conditionalized their

knowledge but they have really memorized in order of the knowledge but they have really memorized in order of the book when to use which formulas and not learned when the book when to use which formulas and not learned when the formulas are actually useful.formulas are actually useful.

• If these same students were to take another test with If these same students were to take another test with questions presented randomly with no hint as to where the questions presented randomly with no hint as to where the formulas were in the book they would not do as well.formulas were in the book they would not do as well.


What knowledge do you have that you know What knowledge do you have that you know exactly when it is useful?exactly when it is useful?

For example: I know how to take derivatives and For example: I know how to take derivatives and velocity is the derivative of position. So if I am velocity is the derivative of position. So if I am presented a velocity vs. time graph all I have to presented a velocity vs. time graph all I have to do to find the position at a given time is to find do to find the position at a given time is to find the area under the curve.the area under the curve.

Fluent Retrieval Fluent Retrieval

““Experts are able to flexibly retrieve important Experts are able to flexibly retrieve important aspects of their knowledge with little attentional aspects of their knowledge with little attentional effort.”effort.”

Effortful Effortful Relatively effortless to automaticRelatively effortless to automatic Leads to progressionLeads to progression Example:Example:

Driving a carDriving a car ReadingReading


EffortfulEffortful NovicesNovices Places demands on the learner’s attention.Places demands on the learner’s attention.

• Attention is being expended on remembering Attention is being expended on remembering instead of learning.instead of learning.

• If a student is trying to learn algebra and they are If a student is trying to learn algebra and they are not an expert in addition, then they will be giving not an expert in addition, then they will be giving attention to the addition instead of learning attention to the addition instead of learning algebra.algebra.

Fluent RetrievalFluent Retrieval

Effortless to AutomaticEffortless to Automatic ExpertsExperts Fluency places fewer demands on their conscious Fluency places fewer demands on their conscious

attention.attention.• Allows more capacity of attention on another task.Allows more capacity of attention on another task.• Like the example before, now, if the student can retrieve Like the example before, now, if the student can retrieve

information on how to add effortlessly or automatically they information on how to add effortlessly or automatically they can focus more on learning how to solve algebraic can focus more on learning how to solve algebraic equations.equations.

Doesn’t mean that experts solve problems faster than Doesn’t mean that experts solve problems faster than novices. Sometimes they can take longer because novices. Sometimes they can take longer because they are attempting to deeply understand the they are attempting to deeply understand the problem.problem.

Fluent RetrievalFluent Retrieval Driving a car. Driving a car.

At first everyone starts out as Novices and they have to At first everyone starts out as Novices and they have to consciously think about all of the moves that are associated with consciously think about all of the moves that are associated with driving.driving.

• Checking mirrors.Checking mirrors.• Checking speed.Checking speed.• Radius of turn.Radius of turn.• How hard to apply brakes and gas.How hard to apply brakes and gas.• Which peddles are the brakes and gas.Which peddles are the brakes and gas.• Turning on your blinker when turning.Turning on your blinker when turning.

After experience however all of this becomes automatic After experience however all of this becomes automatic unconscious thought. unconscious thought.

• People can drive while carrying on a conversation.People can drive while carrying on a conversation.• Sometimes I drive from one destination to another and don’t even Sometimes I drive from one destination to another and don’t even

remember how they got there.remember how they got there.


ProgressionProgression Fluent retrieval is very important so that Fluent retrieval is very important so that

solutions can be easily retrieved from memory solutions can be easily retrieved from memory and you can continuously progress onto and you can continuously progress onto higher learning.higher learning.


ReadingReading When someone starts out learning to read When someone starts out learning to read

they have to sound out the words, usually they have to sound out the words, usually syllable by syllable. It is really hard to focus syllable by syllable. It is really hard to focus your attention on the actual material you are your attention on the actual material you are reading when you have to focus on the words.reading when you have to focus on the words.

After experience, reading becomes automatic After experience, reading becomes automatic unconscious thought and the reader focuses unconscious thought and the reader focuses on what they are actually reading.on what they are actually reading.


What knowledge do you find:What knowledge do you find: Effortful?Effortful? Effortless?Effortless? Automatic?Automatic?

Experts and TeachingExperts and Teaching

““Though experts know their disciplines Though experts know their disciplines thoroughly, this does not guarantee that thoroughly, this does not guarantee that they are able to teach others.”they are able to teach others.”

Expertise in a particular domainExpertise in a particular domain Expert teachersExpert teachers Examples:Examples:

HamletHamlet My 9My 9thth grade Biology Teacher grade Biology Teacher


Expertise in a particular domain.Expertise in a particular domain. Does not guarantee that they will be good at helping Does not guarantee that they will be good at helping

other people learn. other people learn. Can sometimes hurt teaching because experts can Can sometimes hurt teaching because experts can

forget what is easy and difficult for students to learn. forget what is easy and difficult for students to learn. To them it all seems easy.To them it all seems easy.

If they don’t have pedagogical content knowledge If they don’t have pedagogical content knowledge then they are more likely to rely on their textbook for then they are more likely to rely on their textbook for how to teach their students.how to teach their students.

• The textbook doesn’t know anything about their particular The textbook doesn’t know anything about their particular classroom.classroom.

Class could have different prior knowledge and not on the same Class could have different prior knowledge and not on the same level that the book expects.level that the book expects.


Expert TeachersExpert Teachers Know the difficulties that students are likely to face Know the difficulties that students are likely to face

when learning.when learning. Good at knowing what existing knowledge their Good at knowing what existing knowledge their

students have so that they can make new information students have so that they can make new information meaningful.meaningful.

Also good at assessing their students’ progress.Also good at assessing their students’ progress. Have pedagogical content knowledge not just their Have pedagogical content knowledge not just their

content knowledge.content knowledge.• Underlies effective teaching.Underlies effective teaching.

Experts and TeachingExperts and Teaching HamletHamlet

Teacher 1:Teacher 1:• Couldn’t get into the mind set of his students.Couldn’t get into the mind set of his students.• Made them memorize long-passages, do in-depth analyses of Made them memorize long-passages, do in-depth analyses of

soliloquies and write a paper on the importance of language in soliloquies and write a paper on the importance of language in Hamlet. (This sounds really boring to me!)Hamlet. (This sounds really boring to me!)

• Knew all about Hamlet, but not how to teach it to his students.Knew all about Hamlet, but not how to teach it to his students. Teacher 2:Teacher 2:

• Knew how to get into his students heads.Knew how to get into his students heads.• Knew all about Hamlet too, but also how to teach students.Knew all about Hamlet too, but also how to teach students.• Asked them questions about life situations that pertained to Hamlet Asked them questions about life situations that pertained to Hamlet

before even talking about the play. before even talking about the play. Asked about how the students would feel about their parents splitting Asked about how the students would feel about their parents splitting

due to a new man in moms life and that man might be responsible for due to a new man in moms life and that man might be responsible for dads death. Then to think about what would cause them to go mad and dads death. Then to think about what would cause them to go mad and commit murder.commit murder.

This got the students attention and then they were interested in Hamlet.This got the students attention and then they were interested in Hamlet.


Ms. YinMs. Yin Brilliant in the field of BiologyBrilliant in the field of Biology Horrible teacherHorrible teacher

Adaptive ExpertiseAdaptive Expertise ““Experts have varying levels of flexibility in their Experts have varying levels of flexibility in their

approach to new situations.”approach to new situations.”

ArtisansArtisans VirtuososVirtuosos MetacognitionMetacognition Answer-filled ExpertsAnswer-filled Experts Accomplished NovicesAccomplished Novices Examples:Examples:

Japanese sushi expertsJapanese sushi experts Information systems designersInformation systems designers

Adaptive ExpertiseAdaptive Expertise

Artisans Artisans ““merely skilled”merely skilled” Relatively routinizedRelatively routinized


Virtuosos Virtuosos ““highly competent”highly competent” One that is flexible and more adaptable.One that is flexible and more adaptable.

• Learn throughout their lifetime.Learn throughout their lifetime. Not only use what they have learned but are Not only use what they have learned but are

metacognitive and continuously question their current metacognitive and continuously question their current levels of expertise and attempt to move beyond them.levels of expertise and attempt to move beyond them.

But which learning experiences lead develop But which learning experiences lead develop virtuosos. virtuosos.

• Still challenges people.Still challenges people.


MetacognitionMetacognition The ability to monitor one’s current level of The ability to monitor one’s current level of

understanding and decide when it is not understanding and decide when it is not adequate.adequate.• When there are limit’s of one’s current knowledge, When there are limit’s of one’s current knowledge,

you must take the right steps to remedy the you must take the right steps to remedy the situation. Learn more.situation. Learn more.


Answer filled expertsAnswer filled experts A common assumption is that and expert is A common assumption is that and expert is

someone who knows all the answers.someone who knows all the answers. This puts restraint on new learning because This puts restraint on new learning because

experts worry about looking incompetent experts worry about looking incompetent when they might need help in certain areas.when they might need help in certain areas.

They want to be called Accomplished They want to be called Accomplished Novices.Novices.


Accomplished Novices Accomplished Novices Skilled in many areas and proud of their Skilled in many areas and proud of their

accomplishments, but they realize that they accomplishments, but they realize that they do not know everything. They do not know do not know everything. They do not know everything especially when compared to all everything especially when compared to all that is potentially knowable.that is potentially knowable.

Experts being called accomplished novices Experts being called accomplished novices helps people feel free to continue to learn.helps people feel free to continue to learn.

Adaptive ExpertiseAdaptive ExpertiseJapanese sushi expertsJapanese sushi experts

ArtisanArtisan Excels in following a Excels in following a

fixed recipe.fixed recipe.

VirtuosoVirtuoso Can prepare sushi Can prepare sushi

creatively.creatively.

Both can make great sushi but how they are prepared is Both can make great sushi but how they are prepared is different.different.

Adaptive ExpertiseAdaptive ExpertiseInformation systems designersInformation systems designers

Work with clients who know what they want.Work with clients who know what they want. ArtisansArtisans

SkilledSkilled Use their existing expertise to do familiar tasks more efficiantly.Use their existing expertise to do familiar tasks more efficiantly. Tend to accept the problem and its limits as stated by their Tend to accept the problem and its limits as stated by their

clients.clients. VirtuososVirtuosos

CreativeCreative View assignments as opportunities to explore and expand their View assignments as opportunities to explore and expand their

current level of expertise.current level of expertise. Consider the client’s statement of the problem a point for further Consider the client’s statement of the problem a point for further

exploration.exploration.

Experts vs. NovicesExperts vs. Novices

The six principles of expertise need to be The six principles of expertise need to be considered simultaneously, as parts of an considered simultaneously, as parts of an overall system.overall system.


A=28 degreesA=28 degrees Find all other angles.Find all other angles.

Principles of Principles of expertise? expertise?

Are you an expert?Are you an expert?

Experts vs. NovicesExperts vs. Novices A 20-kg mass is attached to a spring with A 20-kg mass is attached to a spring with

stiffness 200 N/m. The damping constant for the stiffness 200 N/m. The damping constant for the system is 140 N-sec/m. If the mass is pulled 25 system is 140 N-sec/m. If the mass is pulled 25 cm to the right of equilibrium and given an initial cm to the right of equilibrium and given an initial leftward velocity of 1 m/sec, when will it first leftward velocity of 1 m/sec, when will it first return to its equilibrium position?return to its equilibrium position?

What expertise do you need to solve this?What expertise do you need to solve this? If you have that expertise, what principles of If you have that expertise, what principles of

expertise are applied?expertise are applied? Are you an expert or a novice?Are you an expert or a novice?


Acceleration of 3-kg mass problem (on Acceleration of 3-kg mass problem (on hand out).hand out).

What expertise?What expertise? What principles of expertise?What principles of expertise? Expert or Novice?Expert or Novice?


A board was sawed into two pieces. One A board was sawed into two pieces. One piece was two-thirds as long as the whole piece was two-thirds as long as the whole board and was exceeded in length by the board and was exceeded in length by the second piece by four feet. How long was second piece by four feet. How long was the board before it was cut?the board before it was cut?

Principles of Expertise?Principles of Expertise?


Puzzle:Puzzle: 5 years ago Kate was 5 times as old as her 5 years ago Kate was 5 times as old as her

Son. 5 years hence her age will be 8 less than Son. 5 years hence her age will be 8 less than three times the corresponding age of her Son. three times the corresponding age of her Son. Find their ages.Find their ages.

What expertise?What expertise? Principles of expertise?Principles of expertise? Expert?Expert?

Experts vs. NovicesExperts vs. Novices First draw a table like this one below:First draw a table like this one below:

5 YRS AGO PRESENT 5 YRS LATER5 YRS AGO PRESENT 5 YRS LATER KATE 5x 5x + 5 5x + 10KATE 5x 5x + 5 5x + 10

SON x x + 5 x + 10SON x x + 5 x + 10

Now we know that 5 years from now Kate's age will be 8 less than three times the corresponding age of her Son. So, if we add 8 to Now we know that 5 years from now Kate's age will be 8 less than three times the corresponding age of her Son. So, if we add 8 to Kate's age , 5 years from now, and make her Son's age 3 times more we will find out 'x' and PROBLEM SOLVED. Kate's age , 5 years from now, and make her Son's age 3 times more we will find out 'x' and PROBLEM SOLVED.

Therefore:Therefore:

5x + 10 + 8 = 3(x + 10)5x + 10 + 8 = 3(x + 10)5x + 18 = 3x + 305x + 18 = 3x + 305x - 3x = 30 - 185x - 3x = 30 - 182x = 122x = 12x = 12 / 2x = 12 / 2x = 6x = 6

Now Kate's Present age is 5x + 5Now Kate's Present age is 5x + 5=5(6) + 5=5(6) + 5= 30 + 5= 30 + 5= 35 YEARS= 35 YEARS

Now her Son's Present age is x + 5Now her Son's Present age is x + 5= 6 + 5= 6 + 5= 11 YEARS= 11 YEARS

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How Experts Differ from Novices Melissa Eubank. How Experts Differ form Novices When it comes to problem solving, experts have gained a lot of knowledge