Carlsen Anthony N, Dakin Chris J, Chua Romeo, Franks Ian M
School of Human Kinetics, University of British Columbia, Vancouver, Canada.
Exp Brain Res. 2007 Jan;176(2):199-205. doi: 10.1007/s00221-006-0610-8.
Recent experiments pairing a startling stimulus with a simple reaction time (RT) task have shown that when participants are startled, a prepared movement was initiated earlier in comparison to voluntary initiation. It has been argued that the startle acts to trigger the response involuntarily. However, an alternative explanation is that the decrease in RT may be due to stimulus intensity effects, not involuntary triggering. Thus the aim of the current investigation was to determine if RT simply declined in a linear fashion with increasing stimulus intensity, or if there was a point at which RT dramatically decreased. In the present experiment participants completed 50 active wrist extension trials to a target in response to an auditory stimulus of varying stimulus intensity (83-123 dB). The presented data show that RTs associated with a startle response are separate from stimulus intensity facilitated responses. Furthermore, this startle facilitation is more highly associated with sternocleidomastoid electromyographic (EMG) activity, rather than the EMG from the widely used startle response indicator muscle orbicularis oculi.
最近将令人吃惊的刺激与简单反应时（RT）任务配对的实验表明，当参与者受到惊吓时，与自愿启动相比，准备好的动作会更早开始。有人认为惊吓会不由自主地触发反应。然而，另一种解释是，反应时的缩短可能是由于刺激强度效应，而非不由自主的触发。因此，当前研究的目的是确定反应时是否仅仅随着刺激强度的增加呈线性下降，或者是否存在一个反应时急剧下降的点。在本实验中，参与者针对不同刺激强度（８３－１２３分贝）的听觉刺激完成了５０次主动腕部伸展至目标的试验。呈现的数据表明，与惊吓反应相关的反应时与刺激强度促进的反应是分开的。此外，这种惊吓促进与胸锁乳突肌肌电图（EMG）活动的关联更强，而不是与广泛使用的惊吓反应指示肌肉眼轮匝肌的肌电图。
