Monday, August 27, 2012

Time course of thematic and functional semantics

I am pleased to report that our paper on the time course of activation of thematic and functional semantic knowledge will be published in the September issue of the Journal of Experimental Psychology: Learning, Memory, and Cognition. This project was led by Solene Kalénine when she was a post-doc at MRRI working with Laurel Buxbaum and me. Humbly, I think this paper is pretty cool for a few different reasons.

First, and most central, we found (using eye-tracking) that the knowledge that two things are used together ("thematic relations", like toaster and bread) is activated relatively quickly and the knowledge that two things serve the same general function (like toaster and coffee maker both being used to prepare breakfast) is activated more slowly. Here are some smoothed activation curves based on our data:

I think this is interesting from the perspective of studying the dynamics of semantic cognition and it is nice from a methodological perspective because, to my knowledge, this is the first time eye-tracking has been used to reveal on-line time course differences in activation of semantic relations the way Allopenna et al. (1998) showed for phonological relations.

Our second cool finding was that context (sentence context, in this case) can emphasize different aspects of functional knowledge. This is a new addition to the existing (and growing) body of evidence that semantic representations are dynamic and context-sensitive, not static and self-contained.

The third thing I like this about this paper is that we were able to have a meaningful interpretation of effects on the higher-order polynomial terms in growth curve analysis. That early-vs-late effect difference between thematic and function relation was on the cubic and quartic terms. Usually these higher-order effects are difficult to interpret because it is not intuitive and hard to mentally picture what a "steeper" cubic or quartic curve would look like. We simplified that task by plotting the GCA curves with and without those higher order terms, so their contribution became easy to see (plotting model fits will be the subject of an upcoming blog post).

Full reference for our paper: 
Kalénine, S., Mirman, D., Middleton, E. L., and Buxbaum, L. J. (2012). Temporal dynamics of activation of thematic and functional knowledge during conceptual processing of manipulable artifacts. Journal of Experimental Psychology: Learning, Memory, and Cognition, 38(5), 1274-1295. DOI: 10.1037/a0027626. Allopenna, P. D., Magnuson, J. S., & Tanenhaus, M. K. (1998). Tracking the time course of spoken word recognition using eye movements: Evidence for continuous mapping models. Journal of Memory & Language, 38(4), 419-439 DOI: 10.1006/jmla.1997.2558

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