1

Chapter 11

Human Processing: Brain, Mind and Language

The Human Brain

• composed of approximately 10 billion nerve cellsneurons

• Axons: take informationaway from cell body

• Dendrites: bring informationto cell body

Sourse: http://faculty.washington.edu/chudler/cells.html

Source: http://faculty.washington.edu/chudler/cellpyr.html(Image used with permission of The Slice of Life.)

Pyramidal neuron in the cerebral cortex.

2

Source: http://faculty.washington.edu/chudler/functional.html

Cerebral cortex

The Cerebral Hemispheres

Source: http://designweb.otago.ac.nz/grant/psyc/TWOBRAIN.HTML

3

The Corpus Callosum• bundle of nerve fibres that serves as connection

between the 2 hemispheres.

Source:http://www.macalester.edu/~psych/whathap/UBNRP/Split_Brain/Corpus%20Callosum.html

Source: http://faculty.washington.edu/chudler/split.html

Contralateral Organization of Brain• in general, the left hemisphere controls movement on right side

of body, and the right hemisphere controls movement on left side of body

• In 95% of right-handers, the left sideof the brain is dominant for language.

• Even in 60-70% of left-handers, theleft side of brain is used for language

4

Source: http://hypatia.ss.uci.edu/psych9a/lectures/lec2notes.html

Contralateral Organization of the Visual Field

Ipsilateral Organization

• Ipsilateral connections are same side connections

• Some ipsilateral connections are found in theauditory cortex

5

Brain Imaging Techniques

1. CT Scans

2. PET Scans

3. Magnetic Resonance Imaging (MRI)

4. Functional Magnetic Resonance Imaging (fMRI)

5. Event-Related Brain Potentials (ERPs)

1. Computed Tomography (CT) Scan• uses a series of x-ray beams passed through head• creates cross-sectional images of the brain• shows the structure of the brain, not the function

Source: http://faculty.washington.edu/chudler/image.html

6

2. Positron Emisssion Tomography (PET) Scans? radioactive material is injected or inhaled? a scanner detects this material when it breaks down ? provides a functional view of the brain

Source: http://faculty.washington.edu/chudler/image.html

3. Magnetic Resonance Imaging (MRI)• uses detection of radio frequency signals produced

by displaced radio waves in a magnetic field• a scanner detects this material

when it breaks down • provides an anatomical view of the brain

Source: http://faculty.washington.edu/chudler/image.html

7

4.functional Magnetic Resonance Imaging (fMRI)• detects changes in blood flow to particular areas of

brain• provides both anatomical and functional view of the

brain

Source:http://www.fmri.org/fmri.htm

5. Event-Related Brain Potentials (ERPs)• record electrical signals emitted from different areas of

the brain• reflect brain activity that is specifically related to some

stimulus or other event

Source: http://faculty.washington.edu/losterho/erplab.htm

8

Source: http://faculty.washington.edu/losterho/erps.htm

Event-Related Brain Potentials (ERPs)

Evidence for Modularity

1. Split brain studies

2. Dichotic Listening studies

3. Aphasia

4. The autonomy of language

Plasticity

9

1. Split Brain Studies

• corpus callosum severed as treatment for epilepsy• visual stimuli are presented simultaneously to the right

and left half of a screen, and the physical objects are placed within reach of either the left or right hand of the subject

• subject fixates on centre of visual display• “key ring” example: key reaches right hemisphere

ring reaches only left hemisphere

Split Brain Study Tasks1.Report what they saw:• Subjects within intact corpus callosum:

Report seeing “key ring”• Subject with split corpus callosum:

Report only seeing word ringv key projected to mute half of brain, and can’t be

transferred to left (speaking) side of brain

2. Reach out and touch what they saw with left hand• Subject with split corpus callosum:

touches keyv contrast in response if language is used

10

Split Brain Study Tasks

New Developments• keep the back of corpus callosum – the splenium, in tact• seizures relieved, but retains some interhemispheric communication

Source:http://hypatia.ss.uci.edu/psych9a/lectures/lec2notes.html

2. Dichotic Listening Test

• two different auditory stimuli are presented simultaneouslythrough earphones to the left and right ears

• the listeners must report what they hear

Source: http://grove.ufl.edu/~tomomi/Intro/Lecture26/sld005.htm

11

2. Dichotic Listening Test (cont’d)

• linguistic stimuli are more accurately reported whenpresented to the right ear

eg. boy to right ear; girl to left earRight-ear advantage

• non-linguistic stimuli are more accurately reported when presented to the left ear

eg. coughing to right ear; laughing to left earLeft-ear advantage

2. Dichotic Listening Test (cont’d)

• processing of acoustic signal dependent upon it beingperceived as a linguistic or non-linguistic stimuli

eg. Syllables contrasting in tone (pitch contours)

Thai: a tone languageSpeakers show a right-ear advantage

English: not a tone languageSpeakers do not show a right-ear advantage

12

Speaking a written word

written text

primary visual cortex

Posterior speech area(including Wernicke’s area)

Broca’s area

Primary mortor cortex

Source:http://faculty.washington.edu/chudler/lang.html#speak

Speaking a heard wordspoken word

primary auditory cortex

Posterior speech area(including Wernicke’s area)

Broca’s area

Primary mortor cortex

Source:http://faculty.washington.edu/chudler/lang.html#speak

13

Broca’s Aphasia• often referred to as agrammatic• problems with production: slow, slurred speech • difficulty with syntax• interpretation requiring syntactic analysis can also be

be problematicThe dog chased the car. (okay)The cat chased the dog. (confusing)

Broca’s Area

Source:http://faculty.washington.edu/chudler/lang.htmlImages: Courtesy of Sice of Life

3. Aphasia

Broca’s Areainvolved in speech productionand syntactic analysis

Broca’s Aphasia Speech SampleHudson, Grover. 2000. Essential introductory linguistics.Blackwell. Oxford.

Yes… ah… Monday… ah… Dad and Peter Hogan, and Dan… ah… hospital… and, ah… Wednesday… Wednesday, nine o’clockAnd ah Thursday… ten o’clock ah doctors… two… two… andDoctors and ah… teeth…

14

Wernicke’s Aphasia

• comprehension difficulties• characterized by verbal fluency without coherence

Source:http://faculty.washington.edu/chudler/lang.htmlImages: Courtesy of Sice of Life

Wernicke’s Area

Wernicke’s Aphasia Speech SampleHudson, Grover. 2000. Essential introductory linguistics.Blackwell. Oxford.

Well, I had trouble with… oh, almost everything that happened form the eh, eh… Golly, the word I can remember you know is ah… When I had the… ah biggest… ah… that I had trouble with, you… that the trouble with,and I still have a … the ah different… The things I want to say… ah..

15

Jargon Aphasia• substitution of one phoneme for another

sable for table• some produce long sequences of uninterpretable “jargon »• show that knowledge of sound sequences can be

disassociated from meaning

Acquired Dyslexia• patients who could read prior to lesion substitute when

reading word lists• may not always substitute same word

S-applaud R1-laugh R2-cheers• some only have trouble with grammatical morphemes

S-which R-no!S-witch R-witch

• such substitutions indicators of lexical organization

4. The Autonomy of Language

Specific Language Impairment (SLI)• acquisition of language is impaired, but general intelligence

develops normally

Contrast• development of language, despite delays in other cognitive

areas

16

5. Plasticity

• originally thought that connections between neuronsdeveloped early, became fixed and could not be changed

• now some strategies have been developed to overcomelanguage processing problems by modifying brainnetworks

Learning a New Language Task (PET)

UnpracticedTask: hearing a text for a new

language taskHighest brain activity• temporal lobe – responsible for

hearing perception• prefrontal cortex – responsible for

understanding language

PracticedTask: knows the task, is spelling outHighest brain activity• Broca’s area - responsible for

the motor control of voice, Source: http://www.epub.org.br/cm/n01/pet/pet.htm

17

Prior to Intervention• Brain activity of 10 year old boyas he identifies sounds of words• reading level: 8 years old

After Intervention• Brain activity after 8 weeks ofspecialized training

• reading level increased by 3 years• images indicate brain activity

changed as well

Source:http://web.sfn.org/content/Publications/BrainBriefings/brain_lang_reading.html

Teaching Reading Strategies : Brain Activity

Language Processing

Psycholinguistics• area of linguistics associated with linguistic performance

The Speech Signal• problem of segmentation• study of spectrograms to learn about acoustic components

that reflect articulatory features of speech sounds

18

Source: http://depts.washington.edu/phonlab/mystery/ Robert Hagiwara

bead bid bade bed bad

bod bawd bode buhd booed

Spectrogram

Speech Perception and Comprehension

The Mental Lexicon• information about sound, spelling, syntactic category andmeaning

Lexical Access• period when information about lexical representation

is made available

Word Recognition• outcome of selection phase

19

Top-Down Processing• uses semantic and syntactic information to process

sensory input• subjects make fewer identification errors on word

recognition tasks if words occur in:a) sentences rather than in isolationb) meaningful sentences rather than nonsense onesc) grammatical sentences rather than ungrammatical ones

• subjects understand words even if with missing phonemesHear wheel in a sentence even if wh is missing

Bottom-Up Processing• comprehension is based solely on incoming sensory input

Factors Affecting Word Recognition

Frequencyhigher frequency – faster recognitionPrimingFaster recognition for semantically related words

doctor nurse recognized faster than flowerReal WordsRecognized faster than nonsense wordsRecencymore recently used words accessed more quickly

20

Syntactic Processing

Garden Path Sentencesharder to process; require back-tracking

1. The bus driven past the school stopped.

2. The horse raced past the barn fell.

3. The horse that was raced past the barn fell.

Speech Production

Planning Unit• speech errors demonstrate that the planning unit

is greater than phonetic segments or individual words

There are many churches in our minister forThere are many ministers in our church

Application and Misapplication of Rulesan istem for a systema burly bird for an early bird