Kanayama Noriaki, Mio Shumpei, Yaita Ryohei, Ohashi Takahiro, Yamawaki Shigeto
Human Informatics Research Institute, National Institute of Advanced Industrial Science and Technology (AIST), Tsukuba, Japan.
Center for Brain, Mind and KANSEI Sciences Research, Hiroshima University, Hiroshima, Japan.
Front Hum Neurosci. 2020 Jan 20;13:460. doi: 10.3389/fnhum.2019.00460. eCollection 2019.
Touching is a fundamental human behavior used to evaluate objects in the external world. Many previous studies have used tactile stimulation to conduct psychological and psychophysiological experiments. However, most of these studies used solid material, not water stream, as an experimental stimulus. To investigate water perception, or to easily control the temperature of an experimental stimulus, it is important to be able to control the water stimulus. In this study, we investigated the usability of water as an experimental stimulus for electroencephalography (EEG) experiments and report the basic EEG response to water stimulus. We developed a tactile stimulation device using a water stream to study EEG responses, with the ability to control the stimulus onset timing. As stimuli, we selected two types of water stream, normal and soft, based on a psychological experiment to confirm a difference of subjective feeling induced by these water streams. We conducted a typical oddball task using the two different water streams and recorded EEG waveforms from 64 electrodes while participants touched the water streams. We calculated P300 at the Pz electrode, alpha asymmetry at the frontal electrodes, and alpha suppression at the parietal area. As a result, we observed typical P300 differentiation based on the stimulus proportion (target 20% and standard 80%). We observed a weaker alpha suppression when participants touched the soft water stream compared to the normal shower. These results demonstrate the usability of water stream in psychophysiological studies and suggested that alpha suppression could be a candidate to evaluate comfort of water stream.
触摸是一种用于评估外部世界物体的基本人类行为。许多先前的研究使用触觉刺激来进行心理和心理生理学实验。然而，这些研究大多使用固体材料而非水流作为实验刺激。为了研究水感知，或者为了轻松控制实验刺激的温度，能够控制水刺激至关重要。在本研究中，我们调查了水作为脑电图（EEG）实验的实验刺激的可用性，并报告了对水刺激的基本EEG反应。我们开发了一种使用水流来研究EEG反应的触觉刺激装置，具备控制刺激起始时间的能力。作为刺激，基于一项心理实验，我们选择了两种水流，即正常水流和柔和水流，以确认这些水流所引发的主观感受差异。我们使用这两种不同的水流进行了一项典型的oddball任务，并在参与者触摸水流时从64个电极记录EEG波形。我们计算了Pz电极处的P300、额叶电极处的α不对称性以及顶叶区域的α抑制。结果，我们观察到基于刺激比例（目标20%和标准80%）的典型P300差异。与正常淋浴相比，当参与者触摸柔和水流时，我们观察到较弱的α抑制。这些结果证明了水流在心理生理学研究中的可用性，并表明α抑制可能是评估水流舒适度的一个候选指标。
