Rethinking neural efficiency: effects of controlling for strategy use.

A sentence verification task (SVT) was used to test whether differences in neural activation patterns that have been attributed to IQ may actually depend on differential strategy use between IQ groups. Electroencephalograms were recorded from 14 low (89 < IQ < 110) and 14 high (121 < IQ < 142) IQ individuals as they performed the SVT with either a spatial or verbal strategy. Event-related desynchronization in upper alpha (9.5-12.5 Hz) and theta (4-6 Hz) bands showed that different strategies evoked different activation patterns, but these patterns did not differ between groups. However, an IQ-related correlate was found in the preparation interval. Thus, although processing patterns during task performance seem to depend on the strategy used for task execution, preparation for task processing may depend on IQ.