Miller D B, Blaich C F
Department of Psychology, University of Connecticut, Storrs 06268.
Dev Psychobiol. 1988 Sep;21(6):523-33. doi: 10.1002/dev.420210603.
Mallard ducklings (Anas platyrhynchos) freeze upon hearing the maternal alarm call, which the hen issues when there are disturbances (e.g., potential predators) near the nest. Our previous work indicates that ducklings that have been devocalized embryonically and reared in auditory isolation exhibit a significant reduction in the incidence of freezing, as compared to vocal ducklings or to devocal ducklings that have been exposed to duckling sounds throughout the perinatal period up to the time of testing at 12 hr posthatch. The main purpose of this paper is to assess whether there is a prenatal or postnatal sensitive period for such auditory experience. Two groups of 30 devocalized ducklings were either (a) stimulated with duckling sounds prenatally and tested to the alarm call at 12 hr posthatch (Expt. 1), or (b) stimulated from the time of hatching to the time of testing at 12 hr (Expt. 2). These experiments rendered no conclusive evidence of either a prenatal or postnatal sensitive period, but they suggested that auditory experience might be important in maintaining freezing. To test this hypothesis, a third group of 30 ducklings was stimulated from hatching to 12 hr and tested at 24 hr (Expt. 3). Only those ducklings receiving auditory experience contiguous with the time of testing (Expt. 2) showed high levels of freezing. Whenever a gap occurred between the offset of stimulation and the onset of testing (Expts. 1 and 3), the incidence of freezing dropped. Thus, auditory experience is important in maintaining the freezing response. This effect contrasts markedly with traditional conceptions of sensitive periods.
绿头鸭幼雏（绿头鸭）听到母鸭发出的警报声时会僵住，母鸭在巢穴附近出现干扰（如潜在捕食者）时会发出这种声音。我们之前的研究表明，与正常发声的幼雏或在围产期直至孵化后12小时测试时一直接触幼雏声音的去声幼雏相比，胚胎期去声并在听觉隔离环境中饲养的幼雏僵住的发生率显著降低。本文的主要目的是评估这种听觉体验是否存在产前或产后敏感期。两组各30只去声幼雏，一组（实验1）在产前用幼雏声音刺激，并在孵化后12小时对警报声进行测试，另一组（实验2）从孵化时到12小时测试时都进行刺激。这些实验没有得出关于产前或产后敏感期的确凿证据，但它们表明听觉体验可能对维持僵住行为很重要。为了验证这一假设，第三组30只幼雏从孵化到12小时进行刺激，并在24小时进行测试（实验3）。只有那些在测试时持续接受听觉体验的幼雏（实验2）表现出高水平的僵住行为。每当刺激结束与测试开始之间出现间隔时（实验1和实验3），僵住的发生率就会下降。因此，听觉体验对维持僵住反应很重要。这种效应与敏感期的传统概念形成了明显对比。
