Tuesday, May 27, 2008

SOLAR Model - Davis & Bowers (2006) in JEP:HPP

For five-letter targets in lexical decision, the authors compare primes of the form 1d345 vs. 13d45. The SOLAR model predicts stronger priming for 1d345. In the original specification of the SERIOL model, open-bigram activation decreased with increasing string position. Under this assumption, the SERIOL model predicts stronger priming for 13d45. Davis and Bowers found stronger priming for 1d345 than 13d45, and concluded that the SERIOL model is inconsistent with their experimental results.

However, the conclusions of Davis and Bowers (2006) are based on an obsolete parameterization of the SERIOL model. In my 2004 dissertation, the assumption that bigram activation depends on string position was dropped; bigram activations now depend only on the separation between the constituent letters. As a result, the SERIOL model, like the SOLAR model, predicts stronger priming for 1d345 than 13d45. Thus the priming results do not actually differentiate between the two models. (For a discussion of why the positional variation was originally included, why it was dropped, and how the model now accounts for the phenomenon originally explained by the positional variation, see Whitney (in press, LC&P) ).

Despite the fact that a primary focus of Davis and Bowers (2006) was to compare the SERIOL and SOLAR models, JEP:HPP did not invite me to review their article. Hence, their article includes claims that are no longer accurate. (It also includes a claim that is outright incorrect - that even if the positional variation were dropped, the SERIOL model would still be inconsistent with their results.) Nor would JEP:HPP allow me to publish a reply. Fortunately, I found a fairer venue, and my reply to Davis and Bowers (2006) is now in press at Brain and Language.

Briefly, the main points of the response are:
  • The SERIOL model is consistent with the results of Davis & Bowers (2006).
  • SOLAR's lexical activation function is not biologically plausible.
  • A recent re-parameterization of the SOLAR model leads a contradiction of Davis and Bower's core claim that contiguity matters.
  • Experimental comparisons between models should test inherent aspects of the models and not depend on particular parameterizations.
  • A critical comparison is presented. That is, I specify a pair of primes for which the two models inherently make different predictions. (Colin Davis agrees with this analysis.)


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This is something really innovative because because it can predict stronger priming for 13d45, that's perfect because it was the information I WAS LOOKING for.