[PS-1.11] Cognitive Load Impairs But Does Not Suspend Contrastive Inferences

Stranahan, E. , Hardenbergh, D. & Snedeker, J.

Harvard University

Working memory load impairs scalar implicature computation [Marty et al. 2013], suggesting quantifier upper-bounds are not encoded lexically. Do scalar adjectives ('tall') encode contrast lexically, or are pragmatic processes required? If contrast is lexical, we expect minimal interference with contrastive inference (CI, [Grodner & Sedivy, 2011]) computation by cognitive load. We manipulated how many letters participants memorized alongside a picture-selection task designed to elicit CIs [G&S]. In both low- and high-load conditions, participants looked equally at a tall pitcher and a tall glass before hearing the final noun when instructed to 'Click on the tall glass' when no short glass was present. But when a short glass was introduced, low-load participants showed a strong preference to look at the tall glass after hearing 'tall', and high-load participants' displayed a similar preference but one significantly weaker 200-300ms after the adjective. Listeners are thus able to use context to derive contrastive meaning even while under cognitive load--suggesting contrast is lexically encoded--but this ability can be impaired under high load---suggesting some aspect of CI computation is pragmatic.