Poster D58, Monday, March 27, 8:00 – 10:00 am, Pacific Concourse
Word Frequency Effects During Ambient Language Processing
Laurel Lawyer1, Andrew Kessler1, Lee Miller1, David Corina1; 1University of California, Davis
Language processing is typically characterized as an obligatory and automatic process. However, whether language mechanisms are fully engaged when we encounter ambient speech is less well understood. In this study we examined whether word frequency effects are detectable during ambient language processing. Methods: 32-channel EEG was acquired while subjects (N=25) passively viewed a 12 minute silent cartoon flanked by concentric flashing checkerboard patterns (visual data not discussed) and heard ambient free-field speech. Speech stimuli consisted of 49 sentences, grouped into three repeated two-minute blocks. Subjects were given no overt task. Results: Responses to open-class words were split into high and low frequency quartiles. Difference waves were analyzed between 0 and 600 msec. using the Mass Univariate Toolbox (Groppe et al. 2011). Cluster mass permutation testing showed significantly larger amplitude responses for low frequency words than high frequency words (p < .01) in bilateral frontal sites, beginning at 140 msec. and persisting through 220 msec. Conclusions: The time course and distribution of these effects is in alignment with previous studies showing early frequency effects using single-word presentation in reading (eg. Penolazzi et al. 2007) and passive auditory oddball paradigms (eg. Shtyrov et al. 2011). The present data illustrates that these effects are not limited to single-word processing and may be evoked in response to ambient speech. This suggests early frequency effects are robust in speech perception and provides further support that lexical processing circuits are engaged automatically, outside of task demands.
Topic Area: LANGUAGE: Lexicon