A new article by Jacob Louis Hoover, Morgan Sonderegger, Steven T. Piantadosi, and Timothy J. O’Donnell, titled “The Plausibility of Sampling as an Algorithmic Theory of Sentence Processing”, will appear in the journal Open Mind: Discoveries in Cognitive Science. This article is based on Jacob’s second Evaluation paper, supervised by Tim and Morgan. 

Words that are more surprising given context take longer to process. However, no incremental parsing algorithm has been shown to directly predict this phenomenon. In this work, we focus on a class of algorithms whose runtime does naturally scale in surprisal—those that involve repeatedly sampling from the prior. Our first contribution is to show that simple examples of such algorithms predict runtime to increase super linearly with surprisal, and also predict variance in runtime to increase. These two predictions stand in contrast with literature on surprisal theory (Hale, 2001; Levy, 2008a), which assumes that the expected processing cost increases linearly with surprisal, and makes no prediction about variance. In the second part of this paper, we conduct an empirical study of the relationship between surprisal and reading time, using a collection of modern language models to estimate surprisal. We find that with better language models, reading time increases superlinearly in surprisal, and also that variance increases. These results are consistent with the predictions of sampling-based algorithms.

A preprint is available at psyarxiv.com/qjnpv