Measuring keyboard response delays by comparing keyboard and joystick inputs.

The response characteristics of PC keyboards have to be identified when they are used as response devices in psychological experiments. In the past, the proposed method has been to check the characteristics independently by means of external measurement equipment. However, with the availability of different PC models and the rapid pace of model change, there is an urgent need for the development of convenient and accurate methods of checking. The method proposed here consists of raising the precision of the PC's clock to the microsecond level and using a joystick connected to the MIDI terminal of a sound board to give the PC an independent timing function. Statistical processing of the data provided by this method makes it possible to estimate accurately the keyboard scanning interval time and the average keyboard delay time. The results showed that measured keyboard delay times varied from 11 to 73 msec, depending on the keyboard model, with most values being less than 30 msec.