Research shows that three years old children can do conditional or if-then reasoning, despite the common belief that it doesn't emerge until 4-5 years in spoken language. The emergence of conditional statement in sign language acquisition fits in this timeline as well.
The ASL-speaking bilingual preschooler Juli (age 3;6) and I had a fun chat about civil services (firefighter, police, and ambulance) and other related topics.
During this conversation, I caught Juli using a partial "if" conditional statement for the first time, if man drives fast, .... I replied, If... what?. Juli completed, police will stop!.
Prior to this time, Juli also appeared to use "when clause" using "before". For example, she signed before you baby, ix-me watched you getting-immunized. Also another time, she signed before ix-me baby, ix-me cried with grandmother. you presentation/lecture (Translated as "When I was baby, I cried with my grandmother while you were (away for) the lecture."
It appeared that Juli began to understand and used a sentence that contain two clauses.
Later that month, Juli produced another clear conditional statement: if you sick, ask-me go-to hospital (translated as "If you're sick, ask me and we go to the hospital). Cute.
Since then, Juli has often used this conditional statement using IF.
This documentation project follows a baby's language acquisition, literacy development, and phonological acquisition in sign language, specifically ASL, week by week from gazing at birth to manual babbling, to first words just before the first birthday in a natural native-ASL environment and visual culture.
The second-year documentation continues to follow the same one-year-old child's language and phonological acquisition and literacy development in ASL on a weekly basis from the one-word stage to two-word and multiple utterances.
The third year documentation continues to follow the same child's ASL language and literacy development on a regular basis from age two to three. It surveys ASL phonological acquisition and more complex utterances.
The fourth year documentation continues to follow the same child's ASL language and literacy development on a regular basis from age three to four. It surveys ASL phonological acquisition and more complex utterances.
This five-year documentation and project follows the bilingual child's natural language acquisition in sign language from newborn to age five.