Eye-tracking and ERPs in multi-word expression research

In recent years, there has been growing interest in the mechanisms that underlie online processing (comprehension and production) of units above the word level, known as multi-word expressions (MWEs). MWEs are a heterogeneous family of expressions that vary greatly in their linguistic properties but are perceived as highly conventional by native speakers. Extensive behavioural research has demonstrated that, due to their frequency and predictability, MWEs are processed differently from novel strings of language. At the very least, MWEs have been shown to be processed faster than matched control phrases. However, behavioural measures are limited in what they can tell us about MWE processing in the brain above and beyond the speed of processing. The present paper argues in favour of two powerful psycho- and neurolinguistic techniques — eye-tracking and event-related brain potentials (ERPs) — and presents a case for why these techniques are particularly suited for the investigation of phrasal frequency and predictive linguistic mechanisms. A number of studies that have drawn on these methods in their exploration of MWEs are reviewed, with a particular emphasis on the unique role of the method and its ability to tap into the underlying mechanisms implicated in MWE processing. It is argued that the two techniques complement, rather than duplicate each other, providing an ever richer account of the (psycho)linguistic phenomenon that MWEs are.