EVENT-RELATED POTENTIAL VARIABILITY AS A MEASURE OF INFORMATION-STORAGE IN INFANT DEVELOPMENT

This article describes the concept of response variability in neuropsy chological development and presents a theoretical rationale for the pr ediction of a decrease in variability in neural responding in the firs t months of life. Methods for measuring variability in brain electrica l activity using event-related potentials (ERPs) are then discussed, f ollowed by a report of a longitudinal study that employed those method s. In that study, 24 infants heard either 64 clicks or 64 tones at 5, 8, 11, 14, and 17 weeks of age. ERP latency variability to tones decre ased significantly across age with this change tending to be linear. A mplitude variability also showed a significant main effect for age in both the early and late windows of the waveform. These results were mo st apparent in the click ERPs, with the declining variability followin g clear linear trends. Tone ERPs appeared to follow age trends that we re similar to click ERPs, but the former were actually quadratic in na ture with variability increasing and then decreasing with age. These r esults are then discussed within the theoretical framework provided ea rlier in the article.