This study demonstrates the feasibility of a minimally obtrusive wearable system that can assess cognitive performance continuously throughout normal life activities by excitation of the peripheral nervous system and detection of the central nervous system response. The new concept was tested with one possible implementation as a device the size of a wristwatch which interrogates the subject by means of haptic excitation (vibration) and records the responses (subtle hand movements detected by accelerometers). The system was programmed to perform simple reaction time trials and was tested with ten volunteers during 8 h of their normal daytime activities. Results indicate that the volunteers responded properly to most of the interrogations (>95%) and that the impact of the device on everyday activities was not significant. The ability to assess cognitive capabilities of individuals continuously during everyday activities could have far-reaching implications for diagnostics and treatment of many different neurological conditions.