Abstract: A data processing method comprises, under program control of test instructions programmed in a mobile computing device, generating and causing displaying on a display device of the mobile computing device, a prompt associated with a first task that tests a feature of a human cognitive domain; in conjunction with causing displaying the prompt, by the test instructions, reading a system clock of the mobile computing device and storing a first time stamp value indicating when the prompt was displayed; by the test instructions, obtaining input via the mobile computing device comprising a response to the prompt; in conjunction with obtaining the input, by the test instructions, reading the system clock of the mobile computing device and storing a second time stamp value indicating when the input comprising the response was detected; by the test instructions, repeating the generating and causing displaying, the obtaining, and the storing the first time stamp value and the second time stamp value, for a plurality of