Abstract：
Response latency is a critical parameter in studying human behavior, representing the time interval between the onset of stimulus and the response. However, different time between devices can introduce errors. Serial port synchronization signal can mitigate this, but limited information is available regarding their accuracy. Optical signals offer another option, but the difference in the positioning of optical signals and visual stimuli can introduce errors, and there have been limited reports of error reduction. This study aims to investigate methods for reducing the time errors. We used the Psychtoolbox to generate visual stimuli and serial port synchronization signals to explore their accuracy. Subsequently, we proposed a calibration formula to minimize the error between optical signals and visual stimuli. The findings are as follows: Firstly, the serial port synchronization signal presenting precedes visual stimulation, with a smaller lead time observed at higher refresh rates. Secondly, the lead time increases as the stimulus position deviates to the right and downwards. In Linux and IOPort(), serial port synchronization signals exhibited greater accuracy. Considering the poor accuracy and the multiple influencing factors associated with serial port synchronization signals, it is recommended to use optical signals to complete time synchronization. The results indicate that under the darkening process, the time error is - 0.23 ~ 0.08 ms (mean). This calibration formula can help measure the response latency accurately. This study provides valuable insights for optimizing experimental design and improving the accuracy of response latency. Although it only involves visual stimuli, the methods and results of this study can still serve as a reference.
摘要：
响应延迟是研究人类行为的关键参数，表示刺激开始和反应之间的时间间隔。然而,设备之间的不同时间可能会引入错误。串行端口同步信号可以缓解这种情况，但有关其准确性的信息有限。光信号提供了另一种选择，但是光学信号和视觉刺激的定位差异会引入误差，关于减少错误的报道有限。本研究旨在探讨减少时间误差的方法。我们使用Psychtoolbox生成视觉刺激和串行端口同步信号来探索它们的准确性。随后，我们提出了一个校准公式来最小化光信号和视觉刺激之间的误差。研究结果如下:首先,串行端口同步信号呈现先于视觉刺激，在较高的刷新率下观察到较小的提前期。其次,提前期随着刺激位置向右和向下偏离而增加。在Linux和IOPort()中，串行端口同步信号表现出更高的准确性。考虑到串口同步信号精度差,影响因素多,建议使用光信号完成时间同步。结果表明,在变暗过程中,时间误差为-0.23~0.08ms(平均值)。该校准公式可以帮助准确地测量响应延迟。本研究为优化实验设计和提高反应潜伏期的准确性提供了有价值的见解。虽然它只涉及视觉刺激，本研究的方法和结果仍可作为参考。
