An economy of effort in communication as an influencing variable in the outcomes of naturalistic adult second language acquisition

Abstract
Stabilising at a limited end-state (“the basic variety”) is common in naturalistic adult second language acquisition. Usage-based theories attribute this to learned attentional biases shaped by L1-tuned processing routines and the low salience, redundancy, and contingency of many grammatical functions. However, research on L2 end-states, adult associative learning, and psycholinguistics suggests an underlying economy of effort: speakers use what works for communication and revise strategies only when necessary. This tendency may influence native and L2 speakers differently as they balance reducing uncertainty with minimising effort. Despite being widely invoked, the concept of economy of effort remains underexplored.
This thesis investigates two questions: (1) Can economy of effort be experimentally operationalised in communicative interaction? (2) Does it affect native and non-native speakers differently? Three studies examined whether task-based interaction success (or failure) prompts increased communicative effort and whether any resulting changes generalise to new contexts.
Study 1 (n=169 monolingual English) normed stimuli and established a method to manipulate communicative effort using abstract figure descriptions. Literal descriptions (e.g., “a large triangle in the middle…”) are more effortful than figurative ones (e.g., “it looks like…”); thus, conservation of effort manifests as a preference for figurative language. Studies 2 and 3 involved online communicative tasks with an artificial interlocutor (researcher confederate). Study 2 (n=90 monolingual English) confirmed a general tendency toward conservation of effort, with communicative breakdowns prompting more effortful strategies only when these differed from prior language experience. Study 3 (n=90 bilingual L2 English) found similar results but with a smaller effect size for non-native speakers.