Numerical cognition in speakers of an Amazonian language with exactly twenty number words.

Recent research has examined the relationship between number word vocabularies and performance on tasks requiring exact number representation and processing. Many studies in this area have focused on a small number of Amazonian languages, which are reported to have highly restricted number inventories, leaving other Amazonian systems comparatively under-documented. Here we investigate the Awetý number system and assess numerical performance of its speakers within the attested counting range for this language. Contrary to prior claims that Awetý counting is limited to five or ten terms, we show that Awetý has a shared conventional counting system consisting of twenty complex verbal expressions. Twelve Awetý speakers were tested using a battery of 13 tasks that assessed counting, verbal and non-verbal array matching, subtraction, and their Approximate Number System acuity. We compared Awetý speakers’ performance on non-verbal tasks to 12 speakers of Brazilian Portuguese. Awetý speakers’ performance was comparable to Brazilian Portuguese speakers across non-verbal number tasks. These findings show that Awetý speakers can reliably represent and operate on exact numbers up to 20, providing new empirical evidence from an under-described Amazonian language.