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Abstract:
Abstract: Prior studies (Hill Karrer, et al., 1998; Karrer
and Ackles, 1990, Wentworth et al., 2000) suggest NSW within the
infant ERP waveform reflects the ability of an infant to utilize
sequential information processing to predict the nature and timing
of upcoming stimuli. The purpose of this study was to investigate
NSW as a measure of expectancy through manipulations of stimulus
omission (SO). Six-month infants (n=36) viewed two female faces
presented within infant-controlled, oddball paradigms of 80 trials.
SO trials were manipulated through three paradigms contrasting
presence or absence of temporal clues of SO and oddball stimuli as
a distracter to expectancy. Simultaneous measures of fixation
duration and ERPs (Grass Model 12 amplifiers, bandpass 0.1-35 Hz)
were recorded within all paradigms. Infants expressed both
behavioral and neural indices (NSW, Pb, Nc, Nc2) of probability and
omission detection specific to the three paradigms. SO detection
was indicated by NSW that typically did not resolve to baseline
until just before stimulus onset of the trial following SO.
Interestingly, infants at risk of developmental delay due to Down
syndrome or Fragile X syndrome did not express NSW during SO (Hill
Karrer, et al., in review). Thus, NSW may reflect expectancy
development during infancy. Supported by NICHD 30868.
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