1. Subjectless Sentences in Child Language
Paul Bloom
1990
Presented by Jodi Davenport

2. Why do children drop the subjects from sentences?
Hug Mommy.
Play bed.
Writing book.
See running.
subjects
Why do children drop the subjects from sentences?

3. Grammatical / Knowledge Theory
Children represent different grammars than adults. Children may all start out with a grammar dropping the subject (as in Spanish or Italian), and later switch their grammar. (Hyams et.al. 1986).
Processing Theory
Children have the same grammar as adults, they drop subjects due to performance factors. (Bloom, this paper)

4. Evidence for Processing Theory
Length limitations occurs even when children imitate adult speech.
Children omit all constituents, not just subjects.
Some children don’t eliminate subjects, but only reduce them.
Evidence against Processing Theory
Children occasionally produce long sentences.
Children drop subjects, but rarely drop objects.

5. Hypothesis: Procedure:
If subject drop is due to processing limitations, sentences with subjects will have shorter verb phrases than those without.
Procedure:
Examine the length of verb phrases in sentences with and without subjects from 3 children (20 hours of recording each) stored in the CHILDES database.

6. Procedure (cont.)
Exclude subjectless sentences acceptable in adult language (i.e. imperatives, “put that down”).
Use sentences with past tense verbs (e.g. “washed”).
Use verbs that denote cognitive states or involuntary acts (nonimperitives, e.g. “need”)

7. Results:
Sentences with subjects had significantly smaller verb phrases than sentences without subjects.

8. Are children omitting the subject when its meaning can be inferred by the listener from context?
Processing Theory
no subject >
short subject >
long subject
Pragmatic Theory
no subject >
short subject =
long subject

9.   Why are subjects omitted more frequently than objects?
Omissions from obligatory contexts
Adam Eve Sarah Total
Subjects 57% 61% 43% 55%
Objects 8% 7% 15% 9%
Processing Theory: There are more processing resources available at the end of the sentence than at the beginning.
Since pronouns have less of a processing load than non-pronouns, pronouns should appear more frequently in subject position than object position.  
Overt non-pronoun subjects should be shorter than overt non-pronoun objects.

10. Possible explanations for why more subjects are dropped:
Pragmatic factors: Subjects convey “given” information while objects convey “new” info.
“Save the heaviest for last”: A bias in language processing that affects both children and adults. The bias may arise from the interaction between grammatical structure and short-term memory within language production. (Bever, 1970).

11. Summary:
This paper has provided evidence in line with processing limitations explanation of subjectless sentences in child language.
Processing theory is a more simple explanation for child’s speech than mis-set parameters of grammar.

12. Comments
Bloom does not offer a compelling explanation for why subjects are much more frequently dropped than objects.
This paper lacks evidence to support the notion that more processing resources are available at the end of the sentence.