| Scope and method of study. The purpose of this study was to determine if increased experience with an auditory stimulus with 3-month-olds would produce novel/familiar differentiation found with older subjects. Participants were 24 infants (3 month-olds) from the Stillwater, Oklahoma area; each subject had three consecutive days of stimulus experience. On Day 1 of testing, 100 presentations of a single tone were given. The next day, subjects received 50 tones identical to Day 1 and 50 presentations of a new tone. On Day 3 of the study, infants heard 50 familiar tones (the Day 1 stimulus), along with 50 presentations of what had been the novel tone on Day 2 (now called New Novel) and 50 presentations of a tone not previously experienced. Average amplitudes, single-trial analyses and latency variability measures were carried out for three peaks (P2, N2, and P3) and at four electrode sites (Cz, Fz, Fpz, and T3). Planned comparisons were done to examine the three hypotheses of the study; ANOVA was also performed to examine any effects beyond the planned comparisons.;Findings and conclusions. The results of the study indicated that the amplitude of the average ERP increased from Day 1 to Day 2 for both the familiar and novel stimulus, an indication of stimulus generalization rather than differentiation. With the additional third day of stimulus experience, it was found that 3-month-old infants do indicate stimulus differentiation with amplitude increases and latency variability decreases for the Day 3-Familiar stimulus over the Day 3-New Novel stimulus. However, the effect was not robust, as is found with older (5-month-olds) and there are more indicators of stimulus generalization than differentiation on Day 3 of stimulus experience. |
