Split hemispheres: competition
-Hemispheres act as two seperate people, can conflict with eachother. The left hemisphere usually
supresses right hemisphere for some actions.
- Sometimes the hemispheres cooperate.
- Left brain damage = can interpret emotions on peoples' face better, left hemisphere interferes with
right hemisphere in interpreting emotions.
- Right brain damage = monotone voice, don't understand emotional expressions, sarcasm or humor.
-Better at understanding spacial relationships. Left hemisphere focuses on details, right on overall
Development of lateralization:
- Brain attends to language sounds, different vowel sounds can be noticed by premature infants.
- Planum Temporale in temporal cortex, larger in left hemisphere for 65% of people.
Maturation of Corpus Callosum: Corpus callosum thickens and grows as myelin increases. Discards many
- Two neurons connected by corpus callosum need to have corresponding functions, genes can't specify
where to attach, therefore they make more connections than needed during development and prune
- Young children resemble split brain people because of immature corpus callosum.
- Born without corpus callosum- similar to split brain, preform poorly on tasks that need use of both
hands. But- unlike split brain can verbally describe objects seen in both visual fields
- Anterior commissure- connects anterior parts of cortex and hippocampal commissure allow
some crossing of information.
- Productivity- ability to improvise new combinations of sounds and ideas
- chimps press keys to type message, don't really understand what they're saying. Don't use new
combinations (low productivity), only ask for things, never describe.
-Resemble humans, Kanzi understood spoken language- understand more than they can produce, use
symbols, request items they don't see, use symbols to describe past events, make new requests.
Nonprimates: Alex the parrot- could understand and speak, describe objects and descriminate between
How did humans evolve language:
1. evolved as a biproduct of overall brain development
OR 2. evolved as specialization.
Biproduct of intelligence:
-If it's due to brain size and development, everyone with normal brain should be able to speak, not true.
- Family with a dominant gene that won't let them speak properly, pronounciation, grammar.
Williams Syndrome: Deletion on chromosome 7, low IQ, poor with visuospatial perception. Musical
ability, friendliness high. Fusiform gyrus twice as large, rest of grey matter small. Language problems,
awkward grammar. Language as a specialization:
Language aquisition device: built in mechanism for aquiring language. Most children develop language
quickly and easily, deaf children develop sign language, even if nobody teaches them official signs.
-FOXP2 gene- mutation= poor language, grammar mistakes. Chimps have them too, affects brain
development and jaw structure.
- People learn second language best if they start younger, if you start after age 12 you'll never reach
level of native speaker.
- Bilingual home = bilateral activation of speech for both languages, frontal cortex thicker.
- If you learn sign language first, can learn english later. If you learn no language (even sign), you can't
Brain damage and language:
- Aphasia= language impairement, brocaès area on left temporal lobe.
- Comprehension deficits when sentences are complicated.
- Can't speak, write, gesture or sign language.
- Omit pronouns, other grammatical things. Can't learn net phrases.
-Trouble understanding same kinds of words that they omit when speaking, misunderstand complex
-Comprehension resembles someone that's distracted, like you're listening to someone with thick
accent. Rely on infrences.
-Can write and speak, language comprehension is poor.
-Wernicke's area in auditory cortex, can't remember names of objects.
- Also known as fluent aphasia, because you can speak fluently.