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Chapter 10 - Language Slide 1 Chapter 10 Language

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Page 1: Slide 1Chapter 10 - Language Chapter 10 Language

Chapter 10 - Language Slide 1

Chapter 10

Language

Page 2: Slide 1Chapter 10 - Language Chapter 10 Language

Chapter 10 - Language Slide 2

Outline

One of the things that really seems to differentiate us fromother animals is our ability to communicate very complexthoughts and ideas from one person to another, even frompeople long since dead.

We will be covering three general issues related to languagein this part of the course, one a day for the next three days.

1) Speaking and listening to language2) Reading and Writing3) The Acquisition of Language

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Chapter 10 - Language Slide 3

Verbal Communication - Speech

Our ability to communicate via speech gives our species ahuge advantage by allowing us to learn things from others,instead of having to learn everything from scratch ourselves.

It also allows for an enhanced ability for cooperativebehaviour as one individual can precisely specify what theywould like another to do.

While other animals do posses some extent of auditorycommunication (e.g., whales & wolves), their form of communication seems much more crude, focused almostcompletely on hunting and mating behaviours.

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Perception of Speech

Our ability to perceive speech is truly amazing … anotherone of those abilities that is very hard to teach a machineto do (though speech recognition devices are now OK).

One of the things that makes speech perception so difficultis the challenging of parsing the speech sound into words.This seems easy to us, but try it with another language.

Once we have figured out where a word begins and ends,then we have to somehow find a match for that sound inmemory, then retrieve the meaning associated with the soundand fit it together with what we have already heard.

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Learning the Rules of Language

In order for anyone to understand what we are saying, wemust form our thoughts into sentences according to a setof rules typically called grammar.

For example, the sentence “George lives in the yellow house”makes sense but “George lives in the house yellow” makes less sense and “George house lives in yellow the” makes nosense at all. In French, the second sentence makes moresense than the first, as the rules concerning adjectives and nouns are different in French.

These rules are also called syntax.

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Learning and Using the Rules

Although most of us can use the rules of grammar quite well,we are not generally very good at stating what the rules are.

The rules seem to be learned and used automatically, withoutus having any explicit knowledge of what they are.

In fact, one of the most famous studies attempting to showour ability to learn without awareness is a study that usesgrammar learning as its base.

The phenomenon it is focussed on has come to be called implicit learning, and a typical experiment goes like ...

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Implicit Learning - Grammer & Stimuli

F G R

D X P S

W L C

Legal Stimuli

DFXGR DWLPS DFWLCS

Illegal Stimuli

DFGPS DWXPR DLWXGR

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Chapter 10 - Language Slide 8

Implicit LearningExperiment & Results

In a typical implicit learning experiment, subjects willfirst be shown a number of “legal stimuli”.

They are then shown stimuli that either do or do not conform to the grammar, and are asked to categorize eachstimulus as legal or not.

Even when the legal stimuli shown in the second part are different from those shown in the first part, subjects canperform the categorization task at above chance levels.

Despite their performance, subjects cannot verbalize thegrammar at all … it is as if they implicitly learned it.

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The Role of Context

We have already discussed the fact that context often exertstop-down effects that aid perception … the same is true ofspeech perception.

In one study, Polack & Pickett (1964) found that subjects could only understand about 47% of spoken words when theywere presented out of context (i.e., as isolated words), butcould understand nearly all of them when presented in theoriginal spoken context.

Similarly, subjects can perceive words better in a noisy environment when the words form meaningful sentences then when they do not.

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Chapter 10 - Language Slide 10

World Knowledge

Thus, we use the structure of the sentence and context tohelp us understand speech, but that is far more to it than that.

Another strong part of our ability to understand speech (andwriting) is our general world knowledge.

Consider the following paragraph:

Tony was hungry. He went to the restaurant and ordered a pizza. When he had finished he realized he had forgotten to take his wallet with him. He was embarrassed.

Thus, much of the meaning of a sentence is not in it. Wheredoes it come from?

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Schema Theory

One theory that helps to explain where we get the additional information is something called schema theory

The general idea is that we have “scenarios” stored inmemory that describe the typical roles and events associatedwith certain situations … similar to the consciousness model?

For example … when we go to a restaurant we expect certainthings to happen; (1) we are seated and given menus, (2) weare given some time, then someone asks us what we want,(3) we order, then wait, (4) our food comes and we eat it,(5) they take our plates and give us our bill, (6) we pay ourbill with money (in our wallet).

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Some Relevant Neuropsychology Findings

Speech Production

An area of left frontal cortex located just in front of the motorcortex controlling the mouth, throat and tongue appears criticalfor allowing us to produce speech - Broca’s area.

If this area is damaged, it leads to a condition termed Broca’sAphasia … a difficulty or inability to produce speech.

This area may contain the “motor memories” that control thefine motor movements needed for accurate speech.

There is also a problem with grammer that occurs, both inproduction and comprehension.

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Chapter 10 - Language Slide 13

Some Relevant Neuropsychology Findings

Speech Comprehension

The recognition of spoken words appears to be performed inthe upper part of the left temporal lobe - Wernicke’s area

If this and surrounding areas are damaged, the comprehensionof speech is impaired, and the production of speech is fluentbut completely meaningless - Wernicke’s Aphasia.

If just Wernicke’s area is damaged, patients show somethingcalled “pure word deafness” … an inability to understandwords despite fine hearing and recognition of other sounds.

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Chapter 10 - Language Slide 14

From the Brain-Cam

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Chapter 10 - Language Slide 15

Reading

The ability to read (and write) extends our communicationabilities beyond both space and, especially, time.

It also allows us to slowly intake information, at our leisure

The “Steve hates phones” example

We will not talk much about writing in this class but, instead,will focus on the question of how it is we are able to read.

> Is there one strategy of reading? Two? More?> What parts of the brain are involved?

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How do we read?

There is still considerable controversy over the exact mental processes involved in reading, but one populartheory is called the dual-route hypothesis.

This hypothesis was inspired by the fact that we mustuse different processes to read items from the two stimulusclasses presented below:

Pronounceable Nonwords Irregular Words

blagid yacht ulker aisle gulgerhaun pneumonia

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The “Dual-Route” Hypothesis of Reading

Printed Word

wholeword

reading(lexicon)

letter recognition

phonologicalrecoding

speech control musclesyacht bonkun

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Chapter 10 - Language Slide 18

Surface Dyslexia

Printed Word

wholeword

reading(lexicon)

letter recognition

phonologicalrecoding

speech control musclesyacht bonkun

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Chapter 10 - Language Slide 19

Phonological Dyslexia

Printed Word

wholeword

reading(lexicon)

letter recognition

phonologicalrecoding

speech control musclesyacht bonkun

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Chapter 10 - Language Slide 20

Semantics - The Meaning of Words

Typically, when we are reading words or listening to someonespeak, our ultimate goal is to understand what they are tryingto communicate to us.

This involves going from the word or speech sound to its meaning (or semantics). How is “meaning” represented bythe brain, and how do we access these meanings?

For many years, the standard assumption was that the meaningof words was represented in a form of mental dictionary called a lexicon.

This view was largely supported by the priming phenomenonthat we discussed previously in this class.

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Example of a Priming Experiment

Task: Simply name the following words as quickly as possible

Subject 1 Subject 2

CARPET CARPETCOUCH DISKSOFA SOFAHAMMER TRUCKCAR CARPICTURE PICTURE

Subjects can namethe items that occurin a related contextfaster than they canname the items thatappear in an unrelatedcontext

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The Lexicon View of Semantics and Priming

sofa

couch

chair

lamp

disk

table

floppy

music

bed

sheet

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Chapter 10 - Language Slide 23

The Lexicon View of Semantics and Priming

sofa

couch

chair

lamp

disk

table

floppy

music

bed

sheet

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Chapter 10 - Language Slide 24

The Lexicon View of Semantics and Priming

sofa

couch

chair

lamp

disk

table

floppy

music

bed

sheet

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Chapter 10 - Language Slide 25

The Lexicon View of Semantics and Priming

sofa

couch

chair

lamp

disk

table

floppy

music

bed

sheet

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Chapter 10 - Language Slide 26

Distributed Representations

More recently, a new view hasbecome popular.

This view assumes that meaningis represented in the brain by thesimultaneous activation of neuronsthat represent the features of a concept.

Priming effects can be accounted for within this distributed view byassuming that related items havesimilar meaning patterns.

“couch”

man-made

has fur furniture

four legs

swims