Willems, Oostenveld, & Hagoort (2008)  EEG tends to be oscillatory  Composed of several different frequency bands  Fourier Decomposition  Theta (4-6 Hz), Alpha (8-12 Hz), Gamma (40-50 Hz), …  Activity in different frequency bands changes in characteristic ways in response to stimuli/tasks  Increase/decrease in amplitude/power  Increase/decrease in synchrony across brain areas  E.g., Theta becomes more synchronized across regions during memory retrieval

Stimuli Spoken Dutch sentences - Picture presented with a Critical Word - Never sentence-final - CW &/or picture Congruent or Incongruent w/ sentence - 41 trials/cond in 4 conds Task = Listen in order to answer questions later Previous work found N400 effects for both words & pix - Scalp distribution often more frontal for pix Critical Word

More on Stimuli & Procedure  Pix appeared at onset of auditory CW and stayed on screen through end of sentence  CWs = 1-syll pictureable nouns beginning w/ stop Consonant  Incongruent CWs always started w/ different stop C  Low constraint context sentences  Congruent CW cloze probability = 16%  Incongruent CWs cloze = 0%  EEG measured from 27 scalp sites  Referred to left mastoid, later re-referenced to both mastoids  16 participants

ERP Results Scalp distribution of N400 effect more frontal than for language-only stimuli

Significance Tests of ERP Results Lang Mismatch & Pict Mismatch both evoke N400 of same size & scalp distribution - Both larger than correct - And not diff from each other Double Mismatch also evokes Larger N400 than Correct - But they never say whether it’s smaller than Lang & Pict!

Percent Power Change (from pre-CW baseline) Over Time in EEG Frequency Bands { { theta alpha { gamma

Diffs Between Conditions in Percent Power Change & Their Scalp Distributions { { theta alpha { gamma

Alpha effects about language Gamma effects about picture

Frequency Components of ERP Difference Waves

Some Interpretation  Increases in theta power in late window in all mismatch conditions  Oscillatory counterpart of N400?  Decrease in alpha power in earlier window in both Lang & Pict Mismatch, but stronger in Lang than in Pict Mismatch  Maybe early detection that spoken word doesn’t match “predicted” word?  Even though cloze is only 16% for congruent words?  Decrease in gamma power in earlier time window for Pict Mismatch compared to both Correct & Lang Mismatch  Early detection of mismatch in visual info from pict w/ sentence context?