ma lecture 4

8/17/2019 MA Lecture 4

1/63

Language Behaviour: Psycholinguistics

Psycholinguistics investigates the mental

mechanisms underlying language

processing. (Cognitive)

How to perceive words and store them in the

mind, how to understand a sentence, how tolearn to read, how language and writing

systems influence mental organizations.


2/63

What is Psycholinguistics

Two Aspects:

Language Comprehension –how weunderstand the meaning of words and

sentences (receptive process)

Language Production –how we speak and

use language (productive process)


3/63

Example: Visual Word Recognition

When people encounter a printed word,

how do they identify it?

Properties of the word

Visual or auditory (Modality)

Orthographic –whether a word is constructed in a legal

way (e.g. “ math” vs “ mtah” )

Phonological (syllable: /cat/; phoneme: /k/, /e/, /t/,

Meaning

Time course of activation of the 3 types of linguistic info in

visual word identification


4/63

Example: Word Recognition

In identifying a written word,

Visuo-orthographic analysis occurs.(activate, activation)

Is the meaning of a word accessedautomatically?

Is the phonological information of a wordaccessed automatically?


5/63


An Experiment:

Task: Speak out the color name of the stimulus youwill view. (red, blue, green)

Requirement: Complete the task as quickly andaccurately as possible.

(The task was devised by Stroop, 1935 --the “ Stroop task” .)


6/63


7/63


8/63


9/63


Expected results:

For color words (red, green, blue), when theirink color is inconsistent with the meaning of

the words,

Naming time is longer (i.e.response latency);

Responses are less accurate.


10/63


Why there is such an interference effect?


11/63

The mental lexicon

red

*

/blu:/

red

blue


12/63

The above finding suggests that themeaning of words is activatedautomatically –people cannot

control the activation of meaning.

automaticity



13/63


What about the phonological information

of a written word in a silent reading task?

Is a word’s phonology activated in a task

that does not require reading aloud?


14/63


Another experiment:

Task: On each trial, you will first see a semanticcategory name (e.g., “flower”). Following thesemantic category, you will see a target wordwhich may be an exemplar of the category(e.g., “rose”). Judge if the target word you willsee is an correct exemplar of the category.


15/63


A servant


16/63


maid


17/63


Type of food


18/63


meet


19/63


Part of a mountain


20/63


peek


21/63


A flower


22/63


rows


23/63


Expected results:

High false “ YES” responses to

homophones of the exemplars.

Suggest that the meaning of words is

accessed via phonology.


24/63

flower

rose/rouz/

rows

rows

Yes

(false)


25/63

Why we do this sort of stuff???

Research on normal readers’ word identificationprocesses provide a solid basis for treating

abnormal readers.

13% poor readers

7-15% developmental dyslexics (dyslexia)

(Developmental dyslexia: Individuals with normal to

high intelligence have severe reading problems.)


26/63

Findings with normal readers indicate that

word meaning and phonology are activated

automatically.

Apply the same tasks to dyslexia. There is a

phonological deficit for dyslexics –they

cannot activate phonological informationobligatorily.


27/63

Research Methodology inPsycholinguistics

1. Reaction time (RT) approach

It measures people’s RT (response latency) to alanguage stimulus. It includes many on-line

methods of studying people’s language behavior

continuously in a laboratory setting“ RT measures time from onset of a stimulus to

onset of a response.”

Infer the mental activity in terms of RTs.


28/63

dog


29/63

dog/dawg/


30/63


2. Memory and Classroom Approach

It investigates language behavior inclassroom, a more natural setting.

To study the developmental pattern of

children’s reading ability:

cross-sectional (grades 1 to grade 5)

longitudinal (a 5-year study)


31/63


3. Eye movements Approach

Use the eyetracker to measure the positionand duration of people’s eye fixations uponthe text

It is a most reliable psycholinguistictechnique.


32/63


How the Eyes Work?

When people read, the eyes do NOT movecontinuously. Instead, the eye will “ stop” on

some word for a brief period (150 to 500

milliseconds). This is called fixation.Between the fixations are periods where the

eye moves rapidly. These rapid eye

movements are called saccades.


33/63


To understand a sentence, the eyes

sometimes move back to some word, re-fixating it. These “ backward” saccades aretermed regression.

Words that are fixated are in the fovea; wordssurrounding the fixated words are in theparafovea.


34/63


A healthy body may seem reward enough for. . . . . . .

177 196 175 244 302 112 177

most people. However, for all those who. . . . .

266 188 199 216 212

question the payoff, some recent research…. . . .

179 266 245 188


35/63


How the Eyes Work?

Fixation Saccades

duration length (characters)

English 231 msec. 7.8

Hebrew 265 msec. 5.5

Chinese 300 msec. 2.0


36/63


How the Eyes Work?

Information extracted from the parafovea aids in reading:

Reading rate is about 200 words per minute when only

the fixated word is visible on each fixation, but it is 300words per minute when both the fixated word and the one

immediately to the right are visible on each fixation.


37/63


4. Neurolinguistic Approach

It studies the brain mechanism for languagefunctioning –where is language functioning

localized in the brain?

Lesion study –using brain-damage patients

Functional brain imaging study –using the

intact human brain


38/63


Lefthemisphere

Righthemisphere

cortex


39/63


Basic Neuroanatomy:

The outer layer of the brain –cerebral cortex

Hidden underneath the cortex are

subcortical parts of the brain

The left and right hemispheres are

connected by a band of nerve fibers –

corpus callosum


40/63


Basic Neuroanatomy:

An important feature of the human nervoussystem is that each cerebral cortex isconnected to the opposite side of the body.

This is termed contralateral connections.

(Same-side connections are very weak.)


41/63


Split-brain patients –those who have a

damaged corpus callosum but an

undamaged brain.


42/63


43/63



44/63


Results:

The left hemisphere is a language

hemisphere. (dominant).


45/63


Brain Imaging Techniques

Language processing requires energy.

Brain imaging techniques depend on the

fact that working brain tissue calls moreblood its way and consumes more

glucose.


46/63



47/63

• General Comments on LesionStudies:

1. The association between language

processing (e.g. syntactic processing)

and the damaged brain areas is direct.


48/63


49/63

2. The primary limitation is that lesions studies

rely on damaged brains. This has severaldrawbacks because

* patients with distinct lesions and specific

functional impairments are rare; in many

case, lesions are large;

* following brain damage, performance may

not reflect normal language processingbecause patients may compensate for their

deficits by using unusual processing

strategies.


50/63

• Can we reliably investigatenormal people’s intact brain by

using noninvasive techniques??


51/63


• Brain Imaging Techniques (PET & fMRI)

Language processing requires energy.

Brain imaging techniques depend on the

fact that working brain tissue calls more

blood its way and consumes moreglucose.

Functional brain imaging:


52/63

Functional brain imaging:

Directly visualize brain activities of normalpeople.


53/63

• PET (positron emission tomography)

Subjects are injected with glucose that

has been tagged with a radioactivesubstance; through this, brain imagescan be got indicating which regions of

the brain have the greatest blood floware are using the most energy.


54/63


55/63

Washington University at St. Louis:

1986: Fox et al., Nature

1988: Fox et al., Science

1988: Petersen et al., Nature1988: Posner et al. Science


56/63

•fMRI (functional magnetic resonanceimaging):

When subjects perform a task (e.g., reading), neural

activity in specific areas of the brain increases. This

results in greater need for glucose and oxygen, both of

which are met by increasing blood flow. There is asmall difference in magnetic susceptibility (a property

of molecules) between oxygenated hemoglobin and de-

oxygenated hemoglobin. With increased blood flow toactive brain areas, there is a change in the proportion

of oxygenated to de-oxygenated hemoglobin. This

difference is detected by MRI scanners.


57/63

Massachusetts General Hospital(Harvard University):

1992: K.K. Kwong et al. (PNAS)

S. Ogawa et al. (PNAS)Peter Bandettini

“ B i I i ” i li th


58/63

“ Brain Imaging ” -- visualize theactivity of the intact human brain


59/63


60/63


61/63


62/63


63/63

• Brain science is (over-)interdisciplinaryand is a team’s work. Psycholinguistics

and Linguistics are parts of it.

ma lecture 4

Documents