Effects of average and specific context probability on reduction of function words BE and HAVE

In a study of word shortening of HAVE and contraction of BE, it is found that both high transitional probability and high average context probability (low informativity) result in reduction. Previous studies have found this effect for content words and this study extend the findings to function words. Average context probability is by construction type, showing that words are shorter in constructions with high average predictability, namely in perfect constructions for HAVE and in future and progressive constructions for BE. These findings show that in cases of grammaticalization, it is not an increase in frequency that results in reduction, but a decrease in informativity.