A growing number of studies support the partial compositionality of idiomatic phrases, while idioms are thought to vary in their syntactic flexibility. Some idioms, like kick the bucket, have been classified as inflexible and incapable of being passivized without losing their figurative interpretation (i.e., the bucket was kicked ≠ died). Crucially, this has never been substantiated by empirical findings. In the current study, we used eye-tracking to examine whether the passive forms of (flexible and inflexible) idioms retain or lose their figurative meaning. Active and passivized idioms ( he kicked the bucket/the bucket was kicked) and incongruous active and passive control phrases (he kicked the apple/the apple was kicked) were inserted in sentences biasing the figurative meaning of the respective idiom ( die). Active idioms served as a baseline. We hypothesized that if passivized idioms retain their figurative meaning ( the bucket was kicked = died), they should be processed more efficiently than the control phrases, since their figurative meaning would be congruous in the context. If, on the other hand, passivized idioms lose their figurative interpretation ( the bucket was kicked = the pail was kicked), then their meaning should be just as incongruous as that of both control phrases, in which case we would expect no difference in their processing. Eye movement patterns demonstrated a processing advantage for passivized idioms (flexible and inflexible) over control phrases, thus indicating that their figurative meaning was not compromised. These findings challenge classifications of idiom flexibility and highlight the creative nature of language.

The literature on idioms often talks about an “idiom advantage,” such that familiar idioms (spill the beans) are generally processed faster than comparable literal phrases (burn the beans). More recently, researchers have explored the processing of idiom modification and while a few studies indicate that familiarity benefits the processing of modified forms, the extent of this facilitation is unknown. In an eye-tracking study, we explored whether familiar idioms and modified versions with 1 or 2 adjectives {spill the [spicy, (red)] beans} are processed faster than matched literal phrases {burn the [spicy, (red)] beans} when both were preceded by a biasing context. The results showed that adjectives inserted in idioms induced longer fixations and were more likely to elicit a regression. However, idiom verbs and final words were processed with the same ease in all adjective conditions, implying that modifying idioms did not impede their processing. In contrast to the widely reported “idiom advantage,” the results demonstrated that canonical and modified idioms were slower to read relative to matched literal controls. This was taken to reflect the competition between an idiom’s literal and figurative meaning, and subsequently the need to select and integrate the contextually appropriate one. In contrast, meaning integration in literal, unambiguous phrases was easier. We argue that processing costs associated with meaning selection may only manifest when idioms are preceded by a biasing context that allows disambiguation to occur in the idiom region, and/or when literal control phrases are contextually appropriate and carefully matched to idioms. Thus, idiom recognition/activation may elicit the well attested idiom advantage, while meaning selection and integration may come at a cost, and idiom modifications may simply add to the cognitive load.

Ambiguous but canonical idioms (kick the bucket) are processed fast in both their figurative ("die") and literal ("boot the pail") senses, although processing costs associated with meaning integration may emerge in postidiom regions. Modified versions (the bucket was kicked) are processed more slowly than canonical configurations when intended figuratively. We hypothesized that modifications delay idiom recognition and prioritize the literal meaning, yielding processing costs when the context warrants a figurative interpretation.To test this, we designed an eye-tracking study, where passivized idioms were followed by "keywords" relating to their literal (bucket-water) or figurative (dead-body) meaning, or were incongruent (time). The remaining context was identical. The findings showed a facilitation for the literal meaning: keywords and passivized idioms in the literal condition were read significantly faster in go-past and total reading time, respectively, compared to both the figurative and control conditions. However, both literal and figurative keywords were processed equally fast (and significantly faster than controls) in total reading time. In support of our hypothesis, the literal meaning of passivized idioms appears to be more highly activated and easier to integrate, although the figurative meaning receives some activation that facilitates its (full) retrieval if necessary. Public Significance StatementThis study shows that altering the form of (otherwise familiar and) ambiguous idiomatic expressions (e.g., the beans were spilled as opposed to spilled the beans) can affect their initial interpretation, with the literal meaning becoming more dominant. Idiomatic meanings are still available but require extra processing effort. The research demonstrates that the way we understand recurrent linguistic units is influenced by how often we encounter them in a particular way.