lec 1- Critical periods in language acquisition

what is a critical period

a strict, time-limited window where specific input is required for normal development. it starts and stops sharply. if the input is missed, the effect is permanent.

eg: a train which only stops at a station once, if your not there when it comes, you cant catch it later.

3 features of a critical period

1. begins and ends abruptly- the window opens and shuts sharply, theres no slow fade

2. external stimuli is compulsory: the brain needs input from the outside world (like sound or language) during that window, or development wont happen properly.

3. cortical areas adapt to other functions: after it closes, the brain repurposes those areas for other jobs.

eg- in a study where kittens had one eye covered for their first few weeks, even after uncovering it, that eye never saw normally, becuase the brain had already given that space to the pther eye

what happens if the input is missed during critical period

the skills cant develop normally, and its permanent. the brain does not wait for the input. it reassigns those areas, so they are not available for that skill later.

eg- baby dicks follow the first moving thing they see in the first day or after hatching (called imprinting), if they dont see thier mom in that window, they wont attach to her later.

what is sensitive period

a gradual window where the brain is at peak responsiveness to input. learning still happens after it closes, but just less efficiently.

eg: sale at sephora, you can get best deal during sale, but you can still buy makeup after, you just pay more

3 features of a sensitive period

1. begins and ends gradually - window fades in and out slowly

2. maximally sensitive to stimuli- during the window, the brain learns the most and fastest efficiently. input isnt strictly needed then, but it works best during this period.

3. after, skills can be acquired but less efficiently- you can still learn it, just slower and harder and you wont reach the same ceiling as someone who learned during the window.

eg: someone who starts piano at 5 vs someone who starts at 30. the 30 yr old can totally learn, but its harder and they probably wont reach the same level as the person who started as a kid.

whats the main difference between a critical and sensitve period

missing a critical period would have permanent damage meaning the door is shut.

missing a sensitive period doesnt permanently shut the foor, you can still learn it, just less efficiently.

in language= sensitive period is common, critical period only applies as a theory, isnt seen in real life.

1. what is L1, and where does the evidecnce for a sensitive period in L1 acquisition come from?

2. explain the aphasia evidence, what happens and what does it show

3. explain the early language deprivation evidence (genie and late sign exposure) what happened and what does it show

1. L1= mother tongue/ first language. evidence comes from :

a. recovery from aphasia= looking at how well people get language back after brain damage, depending on thier age

b. early language deprivation= looking at people who didnt get a language input early in life, like deaf kids with late sign exposure. both of this shows that age matters for language learning, which points to a sensitive period

2. aphasia= loosing language ability becuase of brain damage (stroke/ injury) when kids get brain damage in language areas, they recover language much better than adults with the same damage. a child’s brain is still plastic, so other parts of the brain can rewire and take over language. an adult brain is already set, so it cant make up for the damage as well. this shows an early window where the brain is specifically ready for language, i.e. sensitive period

3. genie= isolated from all languages until age 13. after she was found, she got lots of language input. she could learn word, but she never fully learned grammer. her sentences never came out properly.

late sign exposure= some deaf kids dont get sign language until after the sensitive period, becuase thier hearing parent dont know sign. even after years of signing, thye have permanent gaps in grammar. directs to sensitve period.

1. what is L2, and how does the sensitive period affect learning it?

1. L2= second language, you learn after your first one. the sensitive period doesnt affect all parts of L2 the same way. researchers split language into 3 parts:

a. phonology (sounds)

b. vocabulary (word meanings)

c. morphosyntax (grammar)

late L2 learners find vocab easy, but sounds and grammar stay difficult, so the snesitive period matters the most for soundsand grammar

1. explain phonology and vocabulary in late L2 learners

2. explain morphosyntax in late L2 learners

1. phonology= the sounds of a language. its an area of ongoing difficulty for people who learn an L2 late. even after years, they usually keep a non-native accent, becuase thier brain is already tuned to the sounds of thier L1. eg. an adult who moves to canada, speaks english fluently, but still has an accent.

vocabulary= knowing word meaning. this is relatively easy for late leaners. adults can learn new words quickly, so age doesnt hurt vocab much. eg: you can learn tons of french words at 22 with flashcards

2. morphosyntax= grammar of a language. late L2 learners make grammatical errors alot, meaning the mistakes stick around even after years of using the language and being fluent. eg: adult learner might keep saying “he go” instead of he goes or keep mixing it up. grammar seems to be the most affected part starting late.

1. what is ultimate attainment

2. what is rate of learning

3. why do researchers need to look at both ultimate attainment and rate of learning

1. ultimate attainment= how proficient you can get in a language if you start learning it at a certain age. it is your highest possible level. starting late = lower ceiling, starting early= higher ceiling, especially for grammar and sounds.

2. how fast you pick up a language at a certain age, its about speed not about how good you end up. older learners learn fast at first, but get stuck at a lower level soon. younger learner are slower at first, but end up at a higher level overall. eg: 21 yr old and 5 yr old learning french. after 6 months, 22 yr old is ahead. fter 10 years the kid is better, especially with grammar and accent.

3. becuase they can give opposite answers. if you only look at rate, it looksl ik older is better (they learn faster at first). if you look at ultimate attainment, younger is better (higher ceiling). you need both to see the full picture of the sensitive period

1. what was the hartshone et al (2018) study

2. what is implicit learnign and what does the graph show

3. what is explicit learning and what does the graph show

1. an online study with alot of ppt that looked at how the age you start at affects L2 proficiency, especially grammar.

2. implicit= natural absorption of language with no conscious effort. you pick it up just by being around, this is how kids learn. the graph shows that theres a sloer start, but it keeps raising and reachers a higher ceiling. eg: kid who moves to france picks up french from friends at school without ever studying grammar rules.

3. explicit= consciously studying the language, like learning grammar rules and memorizing patterns. this is how adults usually learn L2. the grpah is faster early on, but it comes flat later. eg: learning french from a book and memorizing verb tables. this matches the rate vs ultimate attainment. explicit learners win on rate (speed), implicit learners win on attainment (final level)

1. what did hartshone et al. find about ultimate attainment

2. what did the researcher find about rate of learning

1. people who started learning by around age 10-12 reached a higher level of syntax (grammar). people who started after that got lower grammar scores and scores kept dropping the later they started. he also suggested that monolinguals (native speakers) scored the highest, and immersion learners (living in the L2 environment where language is spoken) scored higher than non-immersion learners (learning in a class).

2. the rate of syntax learning starts dropping off at 17 age. after 17, brain becomes less efficient at picking up grammar quickly. you can still learn, just slower.

why are younger learners better at reaching L2 proficiency? explain all 6 reasons

1. exposure- starting early= more hours of input over thier lifetime. more input= more learning

2. cognitive processing- kids have limits in how much they process at once. this actually helps, becuase they filter out irrelevant info and focus on what matters in language

3. experiment- kids are more willing to make errors, they dont get embaressed, they try and get corrected. adults avoid mistakes, which slows their learning.

4. immersion- kids are more likely to be fully surrounded by the L2 at school and with friends, so they get constant exposure and practice.

5. motivation- kids have a strong drive to communicate with other kids and fit in, which pushes them to learn faster.

6. maturation and interference- the brain changes as u get older, and ur L1 gets in the way of learning L2. eg- new kid at school doesnt know english but wants to play with other kids, they are surrounded by english all day, they dont care about making mistakes, and they really want to fit in, so they pick english faster.

example of cognitive processing

Kids can only hold small bits of what they hear in their memory at once. So they naturally break language into small pieces, like single words and word endings. That helps them figure out the building blocks and the grammar rules.

Eg: A kid hears "walked," "jumped," "played." Since they're only holding onto small bits, they notice the "-ed" ending keeps showing up and figure out that "-ed" means past tense. That's why kids say "I goed," because they've learned the rule (and are just overusing it).

Adults can hold whole long phrases at once. So they tend to memorize big chunks without ever breaking them down, which means they miss the small grammar pieces inside.

1. what is the maturation hypothesis

2. what is the interference hypothesis

1. the brain itself changes and becomes less flexible with age. our brains are most plastic early in life. as we grow up, brain maturation happens and declines in neural plasticity mkaing the brain more rigid so learning language gets harder

2. the brain is fine, but your L1 is now blocking the L2 from coming in clearly. your L1 gets deeply wired into your brain, so it becomes a lens that filters all new language input, including L2. so when you try to learn L2, you process it through your L1, and your L1 knowledge interferes with L2 learning. EG: DIFFERENCE BETWEEN V AND W being hindi speaker: vine and wine, wapes, vape - L1 filtering L2.

1. besides age, what affects how someone uses L2 daily, and how do older learners compare to younger learnigns in learning rate vs skill level

2. what subtle language differences show up in people who learned an L2 at older ages?

3. speciality of bilingual kids

1. daily communication: how well someone speaks an L2 in everyday life doesnt just dpeend on age, also depends on motivation, time available, and the amount and quality of language input. so an older learner who is motivated anf gets good input can communicate well.

learning rate vs skill level: older learners pick up new skills quickly but may be at a lower level of skill. eg- adult who moves to canada, works in english all day and rrly wants to learn can get great at english fast, even though they started late.

2. special of lexical access- how fast you can pull up a word from meory, late learners bit slower. use of complex grammer- they handle simple sentences fine, but complicated grammar is harder, memory for complex directions, they have harder time remembering long, complicated instructions in the L2.

3. bilingual kids develop skillls in each language only as much as they need it, based on thier own needs and thier environment. so a bilingual kid wont be equally strong in both languages. they’ll be strongest in whichever language they ise more and need more. eg: kid who speaks hindi at home and english at school might know school words like multiplication only in english, anf home words like food names better in hindi