Vossel G, Zimmer H
Psychologisches Institut, Universität Mainz, F.R.G.
Int J Psychophysiol. 1992 Jan;12(1):41-51. doi: 10.1016/0167-8760(92)90041-9.
In recent discussions on the differentiation of orienting, startle and defense responses, the importance of stimulus rise time for the elicitation of different cardiac response patterns was re-emphasized. Especially, it has been claimed that phasic accelerative heart rate (HR) responses-interpreted as indicators of startle-might not only be evoked by auditory stimuli with instantaneous rise times and high intensities, but also by low to moderate stimulus intensities with sudden onsets. The present study examined this question by manipulating rise time (instantaneous vs. 50 ms) and intensity (60 vs. 95 dB). Subjects (N = 120) were randomly assigned to one of the four independent groups. They performed a habituation experiment in which 12 tones of 1000 Hz with a constant interstimulus interval of 90 s were presented. On trial 13, a change in rise time was introduced by reversing the rise time condition in each group (i.e., from instantaneous to 50 ms and vice versa). Examination of HR changes across 4 poststimulus seconds, of maximal HR deceleration and acceleration, as well as examination of magnitude of skin conductance responses (SCRs) indicated clear intensity effects. Rise time, on the other hand, had no effects on HR and SC that could be interpreted as indicative of startle. Thus, it could neither be observed that instantaneous rise time led to stronger accelerative HR responses nor that the combination of instantaneous rise time and high intensity elicited anything but a dominant accelerative response pattern. These findings were also obtained when the first four trials were analyzed separately. As a consequence of stimulus change, larger SCRs as well as larger decelerative HR responses were observed without, however, being affected by the direction of the change in rise time. In sum, the present study suggests that the role attributed to rise time with respect to eliciting qualitatively different cardiac response patterns has been exaggerated. The consequences for the differentiation of different unconditioned responses are briefly addressed.
在最近关于定向反应、惊跳反应和防御反应分化的讨论中，刺激上升时间对引发不同心脏反应模式的重要性再次得到强调。特别是，有人声称，被解释为惊跳指标的阶段性心率加快反应，可能不仅由具有瞬间上升时间和高强度的听觉刺激引发，也可能由突然开始的低至中等强度刺激引发。本研究通过操纵上升时间（瞬间与50毫秒）和强度（60分贝与95分贝）来检验这个问题。120名受试者被随机分配到四个独立组中的一组。他们进行了一项习惯化实验，实验中呈现12个1000赫兹的音调，刺激间隔恒定为90秒。在第13次试验中，通过颠倒每组的上升时间条件（即从瞬间变为50毫秒，反之亦然）引入上升时间的变化。对刺激后4秒内的心率变化、最大心率减速和加速进行检查，以及对皮肤电导率反应（SCR）的幅度进行检查，结果表明存在明显的强度效应。另一方面，上升时间对心率和皮肤电导率没有可解释为惊跳指标的影响。因此，既未观察到瞬间上升时间会导致更强的心率加快反应，也未观察到瞬间上升时间和高强度的组合会引发除主导的心率加快反应模式之外的任何反应。当分别分析前四次试验时，也得到了这些结果。由于刺激变化，观察到更大的SCR以及更大的心率减速反应，但不受上升时间变化方向的影响。总之，本研究表明，上升时间在引发定性不同的心脏反应模式方面所起的作用被夸大了。本文简要讨论了这些结果对区分不同无条件反应的影响。
