Determining the cognitive biases behind a viral linguistic universal: the order of multiple adjectives

When people are asked to create a phrase with the elements {blue, earrings, beautiful}, they produce 'beautiful blue earrings'. Several theories have been proposed about the origins of this universal tendency to order multiple adjectives in a specific way: an innate universal hierarchy with designated positions for each category of adjectives, sensitivity to the definiteness of the adjectival denotation, availability and psychological closeness of the adjective attributes to the speaker, the encoding of subjective vs. objective properties, and the adjective's phonological weight. Although these theories have strong descriptive power, they often focus on what happens at the phenotypic level without explaining what cognitive needs trigger this behavior. Through a timed task that measures acceptability in 'Adjective-Adjective-Noun' sequences that either comply with the universal order or violate it, we adduce evidence for the high acceptability of the violating orders, whose processing did not take longer than that of the compliant orders, as should have happened if the former were non-canonical. The results suggest that ordering preferences exist but are not invariable, as one would expect if a strong linguistic universal was involved. We track the origin of adjective ordering preferences to the synergistic interplay of three cognitive biases: Zipf's Law, Intolerance of Ambiguity, and Novel Information Bias. Last, we show that the linguistic manifestation of these preferences is sensitive to the statistical distribution of the input data, resulting to variation even among speakers of the same language.