Tuesday, May 27, 2008

Guerrera & Forster (2008) in LC&P

The authors investigated priming of eight-letter targets in lexical decision, where the primes employed "extreme transposition". This article includes match scores from the SERIOL model. Again, these scores are based on the original (position-specific) formula for bigram activation, rather than the current assumption that bigram activations depend only on the separation of the constituent letters. Also, the article incorrectly states that the original specification of the SERIOL model placed no limit on the number of intervening letters allowed for bigram activation, whereas this limit has always been two letters.

So here are the match scores under the current parameters, where bigram activation is 1.0 for contiguous letters, 0.8 for a one-letter separation, and 0.4 for a two-letter separation (and 0.0 otherwise).
Note that these numbers are quite different than the published ones for Experiment 3 (in particular) and provide a better fit to those data.

Because bigram activations are no longer positional, the third and fourth primes above now give equivalent match scores. However, simulations give an advantage for matching initial versus final letters due to seriality, as discussed in Whitney (in press).

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