Biological Foundations of Language

Psycholinguistics

Isabel Matos & Sara Pacheco

Biological Foundations of Language

Brain Mechanisms and Language

Lateralization of Language Processes

Brain Mechanisms and LanguageMajor Types of Aphasia

Broca’s aphasia = expressive aphasiaPaul Broca

•Agrammatic speech/writing

•One word at a time

•Able to comprehend

Brain Mechanisms and LanguageImplications for Normal Language Processing

Stimuli

Visual Input

Tactile input

Auditory Input

Visual regionof the brain

Somasentory regionof the brain

Auditory regionof the brain

Wernicke’s area

Wernicke’s area

Wernicke’s area

Arcuatefasciculus

Arcuatefasciculus

Arcuatefasciculus

Broca’s area

Broca’s area

Broca’s area

Caramazza and Zurif (1976)

Broca’s aphasia = lack of production Wernicke’s aphasia = lack of comprehension Conduction aphasia = no relation between both processes

(1) The book that the girl is reading is yellow.

(2) The horse that the bear is kicking is brown.

(3) How many did you see birds in the park?

(4) The little boy fell down, didn’t it?

Broca’s area may

be necessary for syntax

Broca’s aphasics may

be able to construct syntactic

representations but fail to use

them

Linebarger, Schwartz and Safran (1983)

Lateralization of Language Processes

Split-Brain Research

- Severed corpus callosum

- No communication between hemispheres

Preventing epilepsy

What is perceived with the left visual fields goes to the right hemisphere and viceversa.

Lateralization in Normal Brains

Lateralization of Language Processes

Different stimuli for each ear

The dichotic listening task

The visual field task

Broadbent (1954)

Showed

Right ear Left hemisphere

Input Input

Input

Righthemisphere

Contralateral pathway

Ipsalateral pathway

Different stimuli for each ear

The dichotic listening task

Normal Brains

Contralateral pathways

are stronger than Ipsalateral pathways

The dichotic listening task

Split Brains

Right ear Left earSpeechStimuli

Left ear failed because

The contralateral pathway is not helpful – no corpus callosum

The ipsalateral pathway is blocked by the contralateral pathway.

Wood (1975)

Non-linguistic task linguistic task

Greater right hemisphere activityGreater left

hemisphere activity

Left Hemisphere Right Hemisphere

Lateralization of Language Processes

•Better appretiation of pragmatic aspects

o Sarcasm

o White lies

o Humor

•Alternative meanings last longer

Thank you