Understanding when learning begins is critical for identifying the factors that shape both the developmental course and the function of information acquisition. Until recently, sufficient development of the neural substrates for any sort of vocal learning to begin in songbirds was thought to be reached well after hatching. New research shows that embryonic gene activation and the outcome of vocal learning can be modulated by sound exposure in ovo. We tested whether avian embryos across lineages differ in their auditory response strength and sound learning in ovo, which we studied in vocal learning (Maluridae, Geospizidae) and vocal non-learning (Phasianidae, Spheniscidae) taxa. While measuring heart rate in ovo, we exposed embryos to (i) conspecific or heterospecific vocalizations, to determine their response strength, and (ii) conspecific vocalizations repeatedly, to quantify cardiac habituation, a form of non-associative learning. Response strength towards conspecific vocalizations was greater in two species with vocal production learning compared to two species without. Response patterns consistent with non-associative auditory learning occurred in all species. Our results demonstrate a capacity to perceive and learn to recognize sounds in ovo, as evidenced by habituation, even in species that were previously assumed to have little, if any, vocal production learning.

This article is part of the theme issue ‘Vocal learning in animals and humans’.

了解学习何时开始对于识别影响发展过程和信息获取功能的因素至关重要。直到最近，人们认为鸣禽在孵化后很久就可以开始进行任何形式的发声学习，神经基质已经充分发育。新的研究表明，胚胎基因的激活和声音学习的结果可以通过卵内的声音暴露来调节。我们测试了不同谱系的鸟类胚胎在卵中的听觉反应强度和声音学习方面是否存在差异，我们在发声学习（Maluridae、Geospizidae）和发声非学习（Phasianidae、Spheniscidae）类群中进行了研究。在测量卵内心率时，我们将胚胎暴露于（i）同种或异种发声，以确定它们的反应强度，以及（ii）反复同种发声，以量化心脏习惯，这是一种非联想学习的形式。与没有发声学习的两个物种相比，两个具有发声学习能力的物种对同种发声的反应强度更大。所有物种都出现与非联想听觉学习一致的反应模式。我们的结果表明，即使在以前被认为几乎没有发声学习能力的物种中，卵也具有感知和学习识别声音的能力，这一点可以通过习惯化来证明。

本文是主题“动物和人类的声音学习”的一部分。