The effects of tactile stimulation on imprinting in ducklings after the sensitive period

Four-day-old ducklings received visual-plus-tactile exposure to one novel object and visual-only exposure to a different novel object. In a subsequent test, strong suppression of ongoing distress vocalization was exerted only by the object to which visual-plus-tactile exposure had been given. With these results, the experimental conditions under which physical contact is known to facilitate the initiation of imprinting are extended to include subjects that are past the sensitive period.