Frequency of concrete words modulates prefrontal activation during semantic judgments.
The effect of word frequency on semantic processing was characterized by studying two groups of right-handed participants using fMRI. Stimuli were presented in blocks of either high frequency or low frequency word triplets where a sample word appeared above a pair of test words. One group (n = 8) made semantic judgments by selecting the word from the test pair that was more closely associated with the sample. Stimulus triplets were designed such that relatedness between sample and "correct" items was obvious. The other group (n = 8) read the words silently without making any semantic decision and pressed a button on completing the reading of each triplet. Semantic judgments while no less accurate, were associated with greater left prefrontal BOLD signal change when they involved low frequency words, whereas there was no reliable effect of word frequency in the reading condition. These findings suggest that retrieval effort modulates left prefrontal activity when deliberate access to semantics is required.
Chee
Michael W L
MW
Cognitive Neuroscience Laboratory, Singapore General Hospital, Singapore 169856.
Hon
Nicholas H H
NH
Caplan
David
D
Lee
Hwee Ling
HL
Goh
Joshua
J
D000328:Adult; D001931:Brain Mapping; D003071:Cognition / Q000502:physiology; D005260:Female; D006801:Humans; D007091:Image Processing, Computer-Assisted; D007802:Language; D016014:Linear Models; D008279:Magnetic Resonance Imaging; D008297:Male; D011939:Mental Recall / Q000502:physiology; D010100:Oxygen / Q000097:blood; D010465:Perception / Q000502:physiology*; D017397:Prefrontal Cortex / Q000502:physiology*; D011932:Reading; D013060:Speech / Q000502:physiology
D010100:Oxygen