Speaking brains: the language of science

language

not what we say but the way we understand the world and can be visual, written, signed or spoken

McGurk effect

multisensory illusion in which visual information from lip movements changes what a person hears

• dubbed sound “ba” onto video of mouth saying “ga” will hear “da” - compromise between the 2

what effects our ability to understand language

highly dependent on top-down processes - strongly shapred by context

• word identification is not instantaneous

the lexicon

knowledge of words shared by speakers of a language

• includes a word’s phonemic representation, morphological structure and meaning

• an abstraction - exact how, where etc unknown

how are concepts organised

concepts and words into semantic categories where related meanings are linked in memory

semantic priming

semantically related words (bread and butter) activate each other making related words faster to recognise

orthographic neighbours

words with similar spelling - can slow recognition bc compete during word identification

word frequency effect

high frequency words are recognised faster and more easily than low frequency

lateralisation of language

language predominately left hemisphere function

How is language represented in deaf individuals?

sign language activates the same left-hemisphere language areas as spoken language

• Language areas are specialised for symbolic communication and representation not just for speech/hearing.

Perisylvian area

network of brain regions surrounding Sylvian fissure in left hemi = critical for language processing . Includes

• Broca’s area

• wernicke’s area

split brain research

method studying patients who have had a corpus callosum cut (commissurotomy) to treat severe epilepsy, allowing researchers to test left vs right hemisphere functions.

What happens when information is shown to the left visual field in split-brain patients?

processed by the right hemisphere, which cannot communicate with the left hemisphere for speech, so patients often cannot verbally report it.

How does split-brain research show hemisphere differences in language?

The right hemisphere can recognize stimuli (e.g., select objects), but the left hemisphere is needed for verbal report and complex speech production.

role of right hemisphere

social communication like humour, metaphors, figurative meaning

• needed to generate the full richness and colour of language

What is a sensitive period in language development?

developmental window (especially for syntax acquisition around ages 2–4) = brain highly receptive to learning language structure

• after puberty, acquiring fluent syntax becomes very difficult.

Genie Wiley case study

severally isolated and neglected 13 year old = extreme language deprivation in childhood

• after rescue was able to learn some vocab fairly quickly

• struggled with grammar and syntax even after years of training

• her language remained largely telographic (few words and simple phrases)

• supports a sensitive period of language development esp for syntax

• early interactive language exposure is crucial for normal development