Mental Chronometry in the Pocket? Timing Accuracy of Web Applications on Touchscreen and Keyboard Devices

Web applications can implement procedures for studying the speed of mental processes (mental chronometry). As web applications, these procedures can be administered via web-browsers on most commodity desktops, laptops, smartphones, and tablets. This approach to conducting mental chronometry offers various opportunities, such as increased scale, ease of data collection, and access to specific samples. However, validity and reliability may be threatened due to web applications on commodity devices having less accurate timing than specialized software and hardware. We have examined how accurately web applications time stimuli and register response times on commodity touchscreen and keyboard devices running a range of popular web-browsers. Additionally, we have explored the accuracy of a range of technical innovations for timing stimuli, presenting stimuli, and estimating stimulus duration. Results offer some guidelines as to what kind of methods may be most accurate, and what kind of mental chronometry paradigms may suitably be administered via web applications. In controlled circumstances, as can be realized in a lab setting, very accurate stimulus timing and moderately accurate Reaction Time (RT) measurements could be achieved on both touchscreen and keyboard devices. In uncontrolled circumstances, as may be encountered online, short stimulus durations (of up to 100 ms) may be inaccurate, and RT measurement may be affected by the occurrence of bi-modally distributed RT overestimations.