1. Semantic Development Acquisition of words and their meanings
First words at about 12 months
Initially this is a slow, gradual process
Maybe learn a couple of words a week
Object words, commands, some social words (bye-bye)
Then, several months after it begins, word learning speeds up dramatically
Usually begins when child’s vocabulary is around words
The “Vocabulary Burst” or “Naming Explosion

2. The Vocabulary Burst
Rapid increase in the rate of word learning in very early childhood. Estimated that the average 5-year-old knows about 6000 words
If child knows 100 words at 18-months, this means they learn 5900 words over the next 3 ½ years.
Almost 5 words/day
“Fast-Mapping”
How do they do it?
Naming insight: Everything has a name and there’s a name for everything
Application of word-learning strategies or principles specific to this task:

3. Word Learning Principles
Why do we need them?
Quine’s (1960) “gavagai” example
Taxonomic assumption
Words are labels for categories of things
Whole-object assumption
Words label whole objects, not parts or attributes
Mutual Exclusivity
Avoid attaching two labels to the same object
The disambiguation effect (Merriman & Bowman, 1989)

4. Word-learning errors Undergeneralization Overgeneralization
Using a word to narrowly, e.g. only using “cat” for your own pet
More common in early word learning, prior to naming explosion
Overgeneralization
Using a word too broadly, e.g. using “cat” to label cats, dogs, cows, etc…
More common after the naming explosion
Do they really think a cow is a cat? More likely it is “lexical gap filling”

5. Syntactic development
Shortly after the vocabulary burst, kids begin to combine words.
“mommy sock”
Early word combinations typically express a common set of meanings
Recurrence “More bottle”
Negation “No bottle”
Possession “My bottle”
Actor-action “Baby eat”

6. The 14 Morphemes (Brown, 1970)
14 early-learned morphemes that are essential to learning English syntax
plural –s, posessive –s, progressive –ing, past –ed, irregular past, third person -s
in, on
the, a
copula be, auxiliary be (contracted and uncontracted)
Vastly increase the complexity of language
Use Mean Length of Utterance in Morphemes as a measure of children’s syntactic development.

7. What are children learning?
Are they simply remembering and imitating what they hear or are they learning syntactic rules?
Good evidence that they are learning rules
How do children treat words they’ve never heard before: The “Wug” Test
Overregularization of syntactic patterns

8. The “Wug” Test (Berko, 1958) This is a wug. Now there are two
of them. There are two
Can do this for possessive, progressive, past morphemes

9. How do kids do?
Children as young as 3 productively use all of these morphemes on novel words
-ing is acquired the earliest (consistency of form)
Plural, possessive, and past allomorphs next
/wugz/ /wuks/ /wucIz/
/wugd/ /wukd/ /wudId/
Those adding the extra vowel are acquired a little later, but even children as young as 4 regularly apply the correct allomorph to the stem.

10. Overregularization Application of morphological and syntactic rules
Typically see this with irregular forms
Goed, eated, hurted
Mouses, mooses, childs
Children as old as 7 overregularize as will adults learning a new language
Syntactic rules are represented as such, the exceptions are stored explicitly.
Double markings: “wented” or “mices”