Poster E35, Saturday, August 18, 3:00 – 4:45 pm, Room 2000AB
The influence of word imageability on the N400 effect: Preliminary results
Marilyne Joyal1, Sonja A. Kotz2, Christophe Lenglos1, Emmanuelle Renauld1, Maximiliano A. Wilson1, Shirley Fecteau1;1Université Laval, 2Maastricht University
Introduction: Word imageability is the extent and easiness of a word evoking mental imagery. Behavioral studies showed that individuals are more accurate and faster to process higher than lower imageable words in different tasks probing semantics. The N400 effect is an index of semantic processing, as measured by the amplitude difference between two semantic conditions (here, associated and non-associated words). However, event-related potentials (ERPs) associated with word imageability in semantic tasks remain to be elucidated, notably during normal aging. In this experiment, we examined the influence of word imageability on behavioral responses and the N400 effect in healthy elderly participants. We hypothesized that participants will show better behavioral performance for higher than lower imageable words. Further, in line with this expected behavioral difference, we predicted that the N400 effect will differ in size between high and low imageable words. Methods: ERPs were recorded in thirteen elderly participants (mean age=72.8 y.o.; sd=4.3) while they performed a semantic judgment task. Participants were invited to determine if two words presented sequentially were associated or not (e.g. truth – honesty). Imageability (high and low) and association (associated and non-associated) were orthogonally manipulated. Experimental conditions were matched by word frequency, length in letters, orthographic neighborhood size and association strength. ERPs were recorded from 64 scalp positions with Brainvision Recorder software and Brainamp MR Plus amplifiers by Brain Products GmbH. We calculated performance accuracy, RTs (in ms) on accurate responses, and the N400 effect using a time-window of 300 to 600ms post-stimulus onset on four regions of interest (ROIs) encompassing left/right anterior and left/right posterior ROIs. Results: Preliminary behavioral data indicated that participants were more accurate and showed shorter RTs in the high-imageable condition as compared to the low-imageable condition for both associated and non-associated words. The amplitude of the N400 effect was smaller in the high-imageable condition than the low-imageable condition for each of the four ROIs. Conclusion: These preliminary results suggest that there is differential semantic processing for high and low imageable words in elderly participants. Results are in line with the view that perceptual information of concepts influences semantic word processing. Further, this behavioral difference may relate to the reported N400 effects. This difference in the ERP response, that is, a smaller N400 effect for higher than lower imageable words however remains to be further investigated in different aging cohorts.
Topic Area: Meaning: Combinatorial Semantics