Eight-Month-Old Infants Are Susceptible to the Auditory Continuity Illusion

The real world is full of noise and constantly overlapping sounds. However, our auditory system provides a solution to this, that is, the continuity illusion; when we hear a sound stream that is partially replaced by high-level noise, we can restore missing sound information and "fill in" the information as if it were smooth and continuous even against a background of noise. In the present study, we tested the preferences for familiar and novel melodies of 8-month-old infants after a 2-month memory retention interval following 1-week exposure to a specific melody. A preference for familiarity was seen not only when the melody was presented intact but also when it was periodically replaced by high-level noise, which elicits the continuity illusion in adults (Experiment 1). However, a trend toward preference for a novel melody was observed for stimuli periodically replaced by low-level noise that did not satisfy the ecological constraints for the elicitation of the illusion (Experiment 2). For the first time, this study showed that infants as young as 8 months of age are susceptible to the auditory continuity illusion. The study also revealed that the infants could recognize the melody they heard 2 months previously.