So, now that my Div3 is completed, and I just submitted my official penultimate draft, I thought I'd discuss some of the finer points of what I've learned in this journey.
1. Though it stands to reason, my particular study did not find a link between WM and N400 amplitude. There was a trend in adults (p=.063), and the number got lower with cleaner subjects. There was NO correlation in kids with this sample size. I think the lack in statistical power comes from a small sample size, and with data as varied as mine, this would be all it takes to gain significance.
2. Adult data in my study ended up, as expected, being sensitive to the gradient of cloze expectancies. That is, moderately incongruous sentences had shallower N4's than strongly incongruous. Children did not show this effect. Here's my reasoning (right from my discussion page) as to why:
Chall’s (1983) final stage in reading development is being able to grasp metaphor and ambiguous language. This is able to be achieved after years of exposure to different forms, meanings, and uses of words. Additionally, Vygotskii (1965) found that children have more difficulty traits of an object. Just like a cow must have horns to be a cow (even if a dog is temporarily relabeled as a “cow” in the context of a game).
In the current study, the following sentence was rated as moderately incongruous: “She made a jar out of pumpkins.” An adult can more efficiently go through the immediate nodes that would make the sentence false, such as being large, rigid, a plant, and attain the nodes that make the sentence possible: that it’s hollow, they can be small. Accuracy data suggests that children and adults end up perceiving the sentences with the same plausibility. However, increased efficiency in adults is illustrated in significantly longer RT in children for the moderate condition. Working memory, reading ability, and efficiency are likely key to developing this abstraction (Gathercole, 1993), further studies will be needed to better understand the role of these processes.
I think studies like this would help better understand neuropsychological evidence about kids' perception of abstraction. At this stage, I would definitely pursue a study linking complex span (Daneman and Carpenter, 1980) to N400 amplitude. I think with the right ERP task (homograph decoding, Proactive Interference/Release from Proactive Interference), it's totally possible. I would also be interested in if PI/RPI are related to a complex span; this would give insight into executive function and working memory. There are probably such studies out there, I just haven't had the chance to look for them.
Further, I would be interested to see other forms of N4 tasks involving kids/adolescents. Language is the key to human consciousness, so why aren't we looking at our own intellectual roots? I mean, I'm sure we are, but I'd like to know more.
I don't know if I'll be updating this, but I have no particular reason to take it down. When I get back to my library carrel, I'll see if there are any other studies or books of note that should be posted.
But if I don't post again to this particular blog, I will link to whatever project I have next.
Until then, I leave you with the two quotes (which work rather nicely with eachother) found on the front cover of my Div3. They perfectly sum up the importance of the study psycholinguistics:
“Thought and language, which reflect reality in a way different from that of perception, are the key to the nature of human consciousness. Words play a central part not only in the development of thought but in the historical growth of consciousness as a whole. A word is a microcosm of human consciousness.” – L.S. Vygotskii (1965)
"I just look at the words and I know what they say.”-Laura, age 6, from Siegel (1993)