Arredondo Luis T, Perez Claudio A
Department of Electrical Engineering, Universidad de Chile, Santiago, Chile.
Department of Electrical Engineering and Advanced Mining Technology Center, Universidad de Chile, Santiago, Chile.
PLoS One. 2017 Nov 1;12(11):e0186932. doi: 10.1371/journal.pone.0186932. eCollection 2017.
Stochastic Resonance (SR) is a phenomenon, mainly present in nonlinear detection systems, in which the addition of certain amount of noise, called optimal noise, has proven to enhance detection performance of subthreshold stimuli. When added noise is present only during the stimulus, an additional enhancement can be reached. This phenomenon was called time Coincidence Enhanced Stochastic Resonance (CESR). The aim of this study was to study the effect of spatially distributed vibrotactile noise in subthreshold stimuli detection. The correct response rates from two different stimuli conditions were compared, using four tactile stimulator systems to excite four different spatial locations on the fingertip. Under two different conditions, the stimuli were present in only one randomly chosen stimulator. For the first condition, all stimulators contain optimal noise level. In the second condition, the optimal noise was present only at the stimulator with the stimulus. SR threshold principle should not produce different correct response rates between the two conditions, since in both cases the noise enables the subthreshold stimulus to go above threshold. The stimulus signal used was a rectangular displacement controlled pulse that lasted 300ms within a 1.5s attention interval, applied to the exploratory zone of the index finger of 13 human subjects. For all subjects it was found that detection rates were better (p<0.0003) when noise was spatially coincident with the stimulus, compared to the condition in which noise was present simultaneously in all the stimulators. According to our literature review this is the first report of SR being influenced by the spatial location of the noise. These results were not found previously reported, so represent the discovery of a new phenomenon. We call this phenomenon Spatial-Coincidence-Enhanced Stochastic Resonance (SCESR). As results show, the optimal noise level is dependent on the relative position between stimulus and noise.
随机共振（SR）是一种主要存在于非线性检测系统中的现象，在该现象中，添加一定量的噪声（称为最佳噪声）已被证明可提高阈下刺激的检测性能。当仅在刺激期间存在添加噪声时，可实现额外的增强效果。这种现象被称为时间巧合增强随机共振（CESR）。本研究的目的是研究空间分布的振动触觉噪声在阈下刺激检测中的作用。使用四个触觉刺激器系统刺激指尖上四个不同的空间位置，比较了两种不同刺激条件下的正确反应率。在两种不同条件下，刺激仅出现在一个随机选择的刺激器中。对于第一种条件，所有刺激器都包含最佳噪声水平。在第二种条件下，仅在有刺激的刺激器处存在最佳噪声。SR阈值原理不应在两种条件之间产生不同的正确反应率，因为在两种情况下噪声都能使阈下刺激超过阈值。所使用的刺激信号是一个矩形位移控制脉冲，在1.5秒的注意力间隔内持续300毫秒，施加于13名人类受试者食指的探索区域。对于所有受试者，发现与所有刺激器同时存在噪声的情况相比，当噪声与刺激在空间上重合时，检测率更高（p<0.0003）。根据我们的文献综述，这是关于SR受噪声空间位置影响的首次报告。这些结果以前未被报道过，因此代表了一种新现象的发现。我们将这种现象称为空间巧合增强随机共振（SCESR）。结果表明，最佳噪声水平取决于刺激与噪声之间的相对位置。
