Effects of Visual and Auditory Stimulation on Subsequent Visual Preferences in Neonates

The effects of prior exposure to slow or fast temporal frequencies of visual or auditory stimuli on subsequent preferences for visual temporal frequencies were examined in three groups of neonates (N =12 in each group). The 2 Hz group was exposed to lights flashing at 2 Hz prior to half the preference trials and sounds pulsing at 2 Hz prior to the other half of the preference trials. The 8 Hz group was similarly prestimulated with 8 Hz lights and sounds. The control group received no prestimulation prior to preference trials. Preference trials consisted of the presentation of all possible pairs of 2, 4, or 8 Hz flashing lights for 20 sec per pair. Regardless of modality, visual preferences varied systematically with changes in prior stimulation such that there was an inverse relationship between amount of prestimulation and preferred temporal frequency. Infants looked more at slower frequencies and less at faster frequencies as the amount of prestimulation increased from none to 2 Hz to 8 Hz. These effects are similar to those found when internal stimulation is increased by testing neonates before feeding while unswaddled. Thus, we conclude that additional stimulation, whether from external or internal sources, influences neonates' visual attention through general rather than stimulus-specific effects on arousal.