Poster D68, Monday, March 27, 8:00 – 10:00 am, Pacific Concourse
Electrophysiological effects of orthographic neighborhood in a letter detection task
Stephanie Osmond1, Phillip J. Holcomb1, Gabriela Meade1,2; 1San Diego State University, 2University of California, San Diego
A large literature now examines how a variety of lexical factors modulate N400 amplitude, but almost exclusively in tasks that require lexical processing. In these lexically-oriented tasks, words (e.g., drug) with more neighbors (e.g., drag, drum, rug) elicit larger amplitude N400s than words (e.g., tofu) with fewer neighbors. The present study examines whether or not this evidence of co-activated neighbors can also be found in the context of a superficial form-level task. ERPs were recorded as participants decided whether or not a target letter was present in words from high- and low-density orthographic neighborhoods. Behavioral responses were faster overall for target-present stimuli, but were not affected by neighborhood density. N400 amplitude was also sensitive to target presence such that target-absent trials elicited larger amplitude N400s than target-present trials. Interestingly, the presence of the target letter appeared to determine whether or not neighbors were co-activated. When the letter was absent, the classic N400 orthographic neighborhood effect was observed. However, when the letter was present, there was no effect of neighborhood on N400 amplitude. Together, these data suggest that neighbors can be activated in a form-level task, but that early identification of the target letter terminates lexical processing prematurely, thereby minimizing spreading of activation to neighboring lexical nodes.
Topic Area: LANGUAGE: Other