How fast is fast and how slow is slow in mental simulation? Two rating studies on Estonian speed adverbs

Abstract The study explores the language-cognition interface through the semantics of Estonian speed adverbs. It hypothesizes that fastness, being more intense than slowness, is reflected in how adverbs are processed. The expectations are that fast adverbs (e.g., kiiresti ‘fast’) are attributed more extreme speed values than slow adverbs (e.g., aeglaselt ‘slowly’) and that meaning intensification through word formation (reduplication, simile compounding, adding prefixoids) enhances the speed-related meaning of fast adverbs more strongly than those of slow adverbs. Two rating experiments on 86 simple (e.g., kiiresti ‘fast’) and 84 complex adverbs (e.g., üli+kiiresti ‘extra fast’) refute these expectations, notably showing slow simple adverbs as more extreme in slowness than fast adverbs are extreme in fastness. However, meaning intensification – particularly through intensifying prefixoids (e.g., üli+kiiresti ‘extra fast’) and simile compounding (e.g., välk+kiiresti ‘lightning fast’) – amplifies the sense of fastness in both slow and fast adverbs. An exploratory follow-up study on response times shows that fast adverbs (particularly complex fast adverbs) are processed significantly more quickly than slow adverbs. This provides converging evidence for grounded cognition, while the results overall highlight the multifaceted nature of mental simulation, the importance of word-formation mechanisms in meaning reinforcement, and the asymmetries observed in speed adverbs.