Week 6 Update

A couple of interesting things happened this week. First of all, I have been analyzing the CDI of another kid, Reilley. Dr. Ingram actually has three different CDIs of Reilley's, at 1;11, 2;2, and 2;5. (Everyone probably knows this already, but I didn't so I'll explain it anyways. 1;11 is a way to write the child's age. The first number is years and the second number is months, so 1;11 means Reilley was one year and eleven months old when the first CDI was done.) Even though Reilley was so much younger than Quince when this data was taken, they are at similar places in terms of vocabulary as Reilley's language developed normally. This allows me to see in what ways Quince's speech is unusual.

Right now, Dr. Ingram and I are trying to figure out why Quince and Reilley say some words but not others. For example, Quince says pajamas but not shirt. We have a few hypotheses for this right now: 1. The words that the children don't say are generally more complex in structure than the words they do, so they are avoiding the more complex, harder-to-produce words. 2. There are specific sounds within the words that the children don't say that are especially difficult for the children to produce.  3. The words that the children don't say are ones that they aren't exposed to or aren't interested in, so they simply don't need them. 

Personally, I think that it's a combination of these reasons, and probably some others as well. Off the top of my head, I can think of examples from Quince's CDI for all three. For the first one, Quince calls orangutans monkeys, even though he can make all the sounds within the word orangutan, because it's very complicated. For the second one, Quince uses the word pop instead of soda because he can't make the 's' sound. And for the third one, Quince never says the word brother because he doesn't have any. But still, I'm interested in seeing which reasons are more prominent than others.

I'm testing these hypotheses by looking at the data from the CDIs in different ways. To test complexity, I’m calculating the PMLU scores for each of the words. Dr. Ingram actually invented the PMLU score as a way to measure word complexity based on word shape. Each vowel unit (not individual letter) is assigned one point, and each consonant gets two. The higher the score, the more complex the word is. I haven’t started on the specific sounds yet, but I’m probably going to try to identify patterns of particularly prevalent sounds and conspicuous absences in the list of produced words. For the situational part, I’m dividing the words into categories such as foods, clothing items, actions, etc. I’m not really going to be able to look at the exact details, like Quince not saying brother because he doesn’t have one, because I don’t have these details for the other subjects.

Something I'm realizing about this field is that it's a lot more subjective than what I'm used to in the research I’ve done, which is mostly physics/engineering kind of stuff. First of all, how can we define exactly which words the child understands and which the child says (which is what these CDIs are based on)? You can try to test comprehension by putting objects in front of the child and asking them to identify one, but a correct response could be produced through random guessing, or process of elimination using already known objects. And where do you draw the line for ability to produce a word? If the child can repeat it? If the child can respond to a question with it? If the child can label something with it? If the child can use it spontaneously without any prompting? 

This uncertainty is very frustrating for me. I can’t tell what criteria were used to fill out Reilley’s CDIs, so the data might not even be comparable. But I guess it’s good for me to get used to doing this kind of thing too? 

Finally, I’ve been trying to record a lot of Quince’s speech, and I noticed something very interesting. When I record what he says and play it back for him, he listens and tries to correct his own recording. The corrections are clearer and more coherent. This is very exciting for us, as it presents a new technique we might be able to incorporate into his treatment.

Here is an example recording I took of my mom working with Quince. In it, my mom is trying to get Quince to say "mow." On the third try, he manages to get the right vowel sound, and then says "I did it." (I repeated "I did it" afterwards to translate for my mom, because she didn't recognize what he said at first.)

Quince's speech exercise (this is a link, you can click on it)

My mom: Mow
Quince: Ma-me
My mom: Mow
Quince: Ma-me-me
My mom: Mow
Quince: Ma-mo, I dee ee
Me: I did it, ok