Shortly after Juli's first birthday, I noticed something. I pondered about why Juli didn't use the "1" handshape in some ASL words. She used this index finger only in gestural (non-linguistic) pointing, but not in linguistic vocabulary.
Juli (at age 1;3,1) finally used the "1" handshape in some ASL words, such as pineapple, comb and some others later.
Before that, Juli used the "20" handshape in replacement of the "1" handshape when producing these words.
For many months prior to Juli's turning 18 months old (1;6,2), I occasionally pondered whether Juli would form the handshape "R" at this age, whenever I came across the Twin Toddler's video clip below).
Sure enough, Juli had formed the handshape "R" that week (1;6,2). She practiced forming it, but she hadn't linguistically incorporated it into some ASL words that contain the handshape of "R", such as rocket.
Juli would form the handshape "R" when I showed mine. But, when I showed her the incorporation of this handshape into the signed word "rocket", she didn't produce this sign at all yet.
The Twin Toddler had a different situation that they incorporated the handshape R into a signed name because the toddler had a signed name with the handshape R, which explains why it was used regularly in their daily language.
A few weeks later (19 months old, week 30, for the first time, she signed rocket, using the "1" handshape. Interesting, she didn't incorporate the form "R" into this ASL sign.
This case tells something that physical development and linguistic development are separate and the brain is working on integrating them.
This reminds me of the studies that while signing-exposed babies and non-signing infants can point at things using index finger on the gestural/physical level, but these signing toddlers don't incorporate this form into a pronoun on the linguistic level until the same milestone (at about 18-20 months) as the speaking/hearing toddlers.
At a BBQ dinner party in the grandparent's backyard, Juli ran to me. She looked at me and asked home-home and then her gaze turned to the guests and produced bye-bye. I replied (translated as), "No, it's not time yet."
The following referential words and phrases that Juli has used this week: fish hide! (a fish behind the rock), mother car ix-loc (while mouthing "mama"), rocket, ice-cream cold, false, practice (e.g. practice jumping), some more shown in the video above, and other ASL words mentioned in the past months.
Grandma Z's shoes were left in the family room by Juli a while before. As Grandma Z was about to leave for home, we all were in the foyer.
I asked Juli, (translated as) "Where is her shoes." I used the possessive pronoun only rather than "grandma's shoes". Juli left and came back with the grandma's shoes.
Another day, in the bathroom, I made a request for Juli to close the door. Juli left and closed all the bedroom doors and came back. I was expecting the bathroom door. It was interesting how we interpreted differently with no specific to which door I asked for. Talking about a different common sense.