The emergence of canonical babbling in sign language
Canonical (reduplicated) babbling is usually identified with the onset of babbling at around 6-7 months. It consists of reduplicated syllables (i.e. "babababa").
To distinguish canonical babbling (e.g. "bababa") from the earlier marginal babbling (e.g. "ba"), canonical babbling includes syllables in a timing relationship that conforms to mature language restrictions.
The onset of the stage is relatively sudden, and many of these units are reduplicated (e.g. "bababa" and "dadada" in speech or "closing-opening-hand" and "batting-up-down" in signlan).
Ever since the first evening I was out for work, I showed Juli my black workbag to create an association of my long-hours absence with work. I explained to Juli mother drive, go-to work now. mother ix-me will-be home.
The ASL word work had been one of the most frequently used words in the past weeks. Dude went to work -- father go-to work. [bye-bye]. He came back home -- father work done/finish, now home! and such.
Context: Juli (6 months old, week 4) sometimes tilted her head to one side as well as leaned sideway to see what was in there. Opened her arms, palms up especially when standing -- it was like her fad or something. Manually signing-like (difficult to capture it on video at the right time). Vocally and manually babbled. Made razzing visue/sound.
Videoclip: As I was preparing for work another evening, Grandma Z held Juli in arm and explained mother will go-to work. ix-she will come-back. (The first frame of the video showed "work" that I began videotaping a bit late.)
Then Juli babbled, probably imitating what Grandma Z signed. Among the babbles, one stood out distinctly was the ASL word work.
As I was about to leave, I explained to her again including the word work. Juli was producing what looked like "work".
That is, Juli picked up a pattern from our language and produced her first babble based on the pattern of the ASL word, "work".
The emergence of other babbles
Juli still babbled in the ASL form of "work". A few other babbles had emerged this week or before. In addition, gestural communication began to emerge more.
Babbling "dog" in ASL
A month later (m8w4), Juli's paternal relative, who lived out of state, wanted to adopt the dog we temporarily called "Deputy". He asked that we picked him up at SPCA. For the next half week, we had to look after him till the flight date.
As a result, the ASL word #dog and/or the older ASL sign "patting-on-leg" were the most frequently used this week.
Before Deputy flew for his new home, Juli had been babbling the patterned units of the older ASL sign. Juli was patting on her leg.
The day before Deputy departed, Juli woke up one morning. As soon as she sat up herself, she patted on her thigh so distinctively.
Babbling "mama" (vocal)
Juli vocalized "mama" or sometimes whimpered "mmmm" usually when she looked for me in my office when I was out for work.
One day (or night) this week, when I came back home from work, Juli reached out her arms excitedly and vocalized "mamama".
The second time I returned home from work, Juli again reached out her arm and mouthed "mamamama".
Reduplicated syllabic (canonical) babbling
By the end of 7 months old, Juli had babbled manually and vocally much more often, especially with the syllabic pattern of the ASL word "work".
In ASL linguistics, the Symmetry Condition (Battison) states that, if both hands in a two-handed signed word move, then the handshape must be the same and the movement is either alternating or simultaneous. E.g. bath, maybe, etc.
On the other hand, the Dominance Condition states that, if the hand has a different handshape in a two-handed sign, then only the dominant or active hand can move while the base hand remains stationary (not moving). E.g. enough, cookie.
For right-handed signers, the right hand is the active or dominant hand, while the left hand is the passive or base hand. The opposite is true for left-handed signers.
It is a natural rule that governs the structure of signed language. Native signers didn't consciously create this rule.
It is interesting to observe that Juli had been babbling with one active hand onto the base hand. It can indicate that Juli might be right-handed, but it was still early to determine.
Studies show that syllables in vocal babbling prior to around 8th month can be found undifferentiated among babies across different cultures. Then, the patterns in syllables develop a bit more that is found in an adult language of their own culture.
Likewise, the syllables found in Juli's manual babbling appeared to be based on the patterns of ASL words such as: work, shoes, more, be-careful.
These two-handed ASL words had been regularly exposed to Juli for the past months. And, one of the primes (location, movement, and handshape) of the ASL words was similar in one way or another. But, what all of these words had in common was that both hands were in contact.
The critical period of native language
Video: "The linguistic genius of babies" by Patricia Kuhl at TED Talk.
What does preserving a language really means? Record it and preserve it in archival? No. Teach a language to others? No.
To truly preserve a language is to speak (manually or vocally, depending on which language it is) to babies in a native environment, as shown an example in the video: a mother (one of 800 people in the world) speaks Koro to her baby.
Why? It has to do with your brain -- the critical period from birth to age seven.
A study shows that at 6-8 month old babies don't discriminate sounds of different language, but in an amazing short time, at 10-12 month old babies turn head to sounds of a language of their own culture. It is a 2 month critical period. They are absorbing certain sounds of the language and shaping in their brain.
Researchers compare each component of nonreferential babbles with the phonetic inventory of an adult signlan. Yonekawa (1984) suggested the number of primes in each parameter such as handshape, movement and location. In a participant, 29% of handshape, and 54% of movement inventory in adult JSL were used in non0referential gestures. discuss that nonreferential babbles with the phonetic inventory of adult JSL.
Petitto and Marentette (1991) showed that 32% of the handshape and 54% of the movement that made up the phonetic inventory of adult ASL were observed in manual babbling. These nonreferential gestures are produced before the onset of signed words.
Native-signlan people who are Deaf (with a capital letter of "D") around the world are truly living preservers, ranging from accurate sign production (or "pronunication") to pragmatics (contexts and discourse styles).
Understanding the difference between babbles and words
Studies (Petitto) show that the stages of language acquisition from birth to age 5 and beyond are identical in both visual-spatial modality and vocal-auditory modality.
You might wonder what's with those claims in the "baby sign language" discourse that infants acquire signs earlier than spoken words.
Older studies from a group of researchers (e.g. Bonvillian and others) used such methodological techniques as follows:
In a linguistic standard, if vocal productions within this period (syllabic babbling stage at 7-10 months) are not used referentially, they are considered babbling. But, in these studies, the "recognizable" manual productions were not used referentially by infants and they were misinterpreted as "first signs".
Likewise, we know that when a baby vocally babbles "ma-ma", "pa-pa", or such at 6-7 months, these babbles are not attached to the mother, grandpa, or such respectively. Babies understand the link between the word and its referent at later months (average at 12 months).
Let's look at a scenario: a mother signed "milk" and her baby duplicated it. She was excited, videotaping her baby's first manual production (closing and opening 5-handshape), uploaded it online, and headlined it "6 months old signing 'milk'".
The baby in the video was clearly babbling -- closing and opening hand repeatedly. It is equivalent to "bababa, bababa" in vocal form. The baby was not signing "milk", even though the movement and handshape are similar.
It is no difference in signlan and speech. But, often parents interpret an infant producing something (e.g. commonly "milk" or "more") in visual-spatial modality as "first sign", when in fact it is syllabic babbles. A syllabic structure of manual babbling is often mislabeled for a first sign.
References / suggested readings
Bénédicte de Boysson-Bardies. Developmental neurocognition: speech and face processing in the first year. Pp 366-369.
Also see variegated babbling in sign language.