Idiom and proverb processing in autism: a systematic review and meta-analysis

Kinga Morsanyi,Dušan Stamenković

doi:10.1007/s41809-021-00079-4

Kinga Morsanyi, Dušan Stamenković

Open Access

https://doi.org/10.1007/s41809-021-00079-4

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Abstract

Figurative language processing impairments in autism have been widely demonstrated, and have been considered a defining feature of autism. Studies in this area often consider different types of figurative language together, and less attention has been paid to identifying the factors that might contribute to difficulties in processing specific types of figurative language. Here we present a preregistered systematic review and meta-analysis of studies assessing the comprehension of idioms and proverbs in autism spectrum disorder (ASD) as compared to typically developing (TD) individuals. Idioms are widely used multi-word figurative expressions, which are understood by using contextual information. Proverbs are a related type of fixed, figurative, formulaic expression in a sentential form, typically linked with wisdom. Idioms and proverbs represent forms of figurative language which are more conventionalized and frequently opaquer than metaphors, pointing to a unique way that they are processed in conversational contexts. Our analysis encompassed a total of 11 studies from 10 papers (involving 235 autistic and 224 TD individuals), which met our inclusion criteria (the ASD and TD groups were matched on both chronological age and intelligence). The analysis of accuracy data revealed a group difference favouring the TD over the ASD group, with a medium effect size, and no indication of a publication bias. Participants’ age was unrelated to the magnitude of group differences, but there was a trend for smaller group differences in the case of participants with higher (verbal) intelligence. We discuss these findings with reference to theories related to the nature of figurative language impairments in autism.

Highlights

In light of the above considerations, we present a systematic review and meta-analysis, focusing on idioms and proverbs, both of which represent conventionalized, and often opaque forms of figurative language, which points to a unique way they are processed in conversational contexts
The studies are listed in the table in rank order of effect size (Hedge’s g) for the group difference in performance on the idiom or proverb task(s), from positive to negative
Some studies assessed language skills with multiple tests, the most common strategy was to match the groups on the Vocabulary subtest of the Wechsler Intelligence Scale. This meta-analysis focused on idioms and proverbs, two special forms of figurative language, which are more opaque and conventionalized than metaphors, and, for this reason, rely more heavily on the processing of contextual cues, and might be more difficult to process

Summary

Introduction

Autism is a neurodevelopmental disorder, which, according to some current estimates (Maenner et al 2020), affects about 1 in 54 people. There are some characteristic features of autistic cognition, which involve orientation toward detailed perceptual features (often at the expense of central coherence), impairments in social imagination (for example, in imaginative play) and, most importantly for the present discussion, deficits in communicative behaviours (e.g., Bal et al 2019; Happe & Frith, 2006; Lobban-Shymko et al 2017; Pellicano et al 2006; Rajendran & Mitchell, 2007). Autistic people have been found to be less susceptible to some reasoning biases and memory illusions than typically developing people (e.g., De Martino et al 2008; Morsanyi et al 2010; Wojcik et al 2018), these findings may be attributed to impairments in the automatic processing of linguistic information in context (Pijnacker et al 2010)

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