Modality effects in the cultural evolution of language: An experimental iterated learning approach

Abstract

Cultural evolution has been proposed as the mechanism by which human languages’ distinct

features emerge. One of such features is structure, which is regarded as an optimal solution

to the competing pressures for simplicity and expressivity in language learning and use. A recent

experimental iterated learning study (Kirby et al., 2015) shows that structure can emerge

from an unstructured language under these competing pressures, by implementing both a

learning and a communication task in a transmission chain setup. However, as most iterated

learning experiments, it was run on a written modality, which might be problematic if the aim

is to drive conclusions about language in general—writing is not language’s default modality

and was not present in early stages of language evolution.

The present study carried out a partial replication of the aforementioned experiment,

contrasting a written condition (analogous to the original) with a spoken condition, in order

to test for possible modality effects. Results for the written condition did not replicate those

in Kirby et al. (2015) in any of the measures, suggesting that motivational factors could have

played a crucial role in the previous findings. This hinders the interpretations of modality

effects and suggests the need of further work.