ERP study of the development of the holistic and analytic modes of processing between 6 and 8 years

Event-related potentials (ERPs) were recorded (01, 02, Fcz, Cpz leads) from 32 normal children aged from 6 to 8 years during a categorisation task performed with 4 types of stimuli that allowed for a holistic and/or an analytic development to modify information processing according to the child's age. Whatever age, derivation or stimulus, the individual ERPs showed a large negative N2 wave (mean latency: 230 ms) made up of two widely overlapping components. In order to separate these components, an initial principal component analysis (PCA) was performed on the waveforms; this PCA provided a principal component that accounted for the amplitude difference between the first negative peak of the N2 wave (180 ms after stimulus onset) and the subsequent slope change. A second PCA was then carried out on the corresponding individual component scores; this second PCA provided two factors according to whether the stimuli were holistically or analytically processed. Regarding the pre- and post-vertex data (Fcz and Cpz), these two factors accounted for the same ERP effect for the 6-year-old children but opposite effects after the age of seven. We interpreted this change as reflecting the differentiation of specific - holistic and analytic - modes of processing from a non-specific mode after the establishment of the concrete operation period.