RESUMEN
The reward positivity (RewP) is a widely studied measure of neural response to rewards, yet little is known about normative developmental characteristics of the RewP during early childhood. The present study utilized a pooled community sample of 309 4- to 6-year-old children who participated in the Doors guessing game to examine the latency and amplitude of the RewP. Peak detection of the gain-loss difference waveform was conducted for electrodes Fz, Cz, Pz, Oz and the mean activity in a 100 ms window centered around this peak was analyzed. There was a significant decrease in RewP latency (RewP was earlier) and increase in RewP amplitude (RewP magnitude was larger) with advancing age in this cross-sectional analysis. Further, these were independent effects, as both RewP latency and RewP amplitude were uniquely associated with children's age. Moreover, our results indicate that the RewP latency in 4- to 6-year-olds falls outside the 250-350 ms window typically used to quantify the RewP (RewP latency in our sample = 381 ms; SD = 60.15). The internal consistency for latency (.64) and amplitude (.27) of the RewP were characterized by moderate to low reliability, consistent with previous work on the reliability of difference scores. Overall, results demonstrate RewP differences in both timing and amplitude across age in early childhood, and suggest that both amplitude and latency of the RewP might function as individual difference measures of reward processing. These findings are discussed in the context of methodological considerations and the development of reward processing across early childhood.