Rydén O O
J Comp Physiol Psychol. 1980 Jun;94(3):426-35. doi: 10.1037/h0077680.
Nine great tit nestlings were exposed to two synthesized auditory stimuli: a replica of a high-pitched alarm call, a part of the species' vocal repertoire, and a control stimulus, identical to the alarm call with respect to amplitude, duration, frequency span, and frequency modulation but having a lower frequency range (8.6--8.1 kHz vs. 4.5--4.0 kHz). The alarm call released a defensive reaction characterized by (a) a prolonged heart rate (HR) acceleration, (b) increased electromyographic activity, and (c) behavioral immobility. The control stimulus elicited a transient HR acceleration and a muscular reaction indicative of a startle reflex. It is concluded that high pitch is a critical feature of the alarm call. It is proposed that the impact of the alarm call is a consequence of the nestlings' primary experience with sounds in the low to middle frequencies, in particular, with the parental feeding call and their own begging call. Embryological maturation of auditory responsiveness, starting with a sensitivity to low-frequency sounds, may contribute to the establishment of a basic tendency to approach low-frequency stimulation and show aversive reactions to high-frequency stimulation. In contrast to earlier interpretations, it is suggested that a strong accelerative HR response is not associated with a reduced stimulus sensitivity per se but rather with an altered distribution of attentiveness.
一种是高音警报叫声的复制品，这是该物种发声库的一部分；另一种是对照刺激，在振幅、持续时间、频率范围和频率调制方面与警报叫声相同，但频率范围较低（8.6 - 8.1千赫兹对比4.5 - 4.0千赫兹）。警报叫声引发了一种防御反应，其特征为：（a）心率（HR）长时间加速；（b）肌电图活动增加；（c）行为静止不动。对照刺激引发了短暂的心率加速和一种表明惊吓反射的肌肉反应。得出的结论是，高音是警报叫声的一个关键特征。有人提出，警报叫声的影响是雏鸟对低频到中频声音的主要体验的结果，特别是对亲鸟喂食叫声和它们自己的乞食叫声的体验。听觉反应性的胚胎学成熟从对低频声音的敏感性开始，这可能有助于建立一种接近低频刺激并对高频刺激表现出厌恶反应的基本倾向。与早期的解释不同，有人认为强烈的心率加速反应本身并不与刺激敏感性降低相关，而是与注意力分配的改变有关。
