Paul D. Toth

The impact of instruction on second-language implicit knowledge: Evidence against encapsulation

This paper compares explicit instruction in second-language Spanish with a control treatment on a written picture description task and a timed auditory grammaticality judgment task. Participants came from two intact, third-year US high school classes, with one experiencing a week of communicative lessons on the Spanish clitic se (n = 15) and the other exposed to se only incidentally (n = 20). Explicit instruction consisted of grammar rules with sentence-level examples, followed by communicative tasks. Three test versions were administered within a split-bloc design as a pretest, immediate posttest, and delayed posttest 6 weeks after instruction. The instructed group increased targetlike uses of se on both tasks and sustained gains through the delayed posttest, although first-language transfer errors persisted. Meanwhile, overgeneralization errors centered on semantic and syntactic contexts similar to the instructional object, aligning with the unergative–unaccusative distinction among intransitive verbs. It is argued that the data provide evidence for the permeability of second-language implicit knowledge to explicit instruction and against total encapsulation as a model of the mind.