Apparatus, system, and computer-readable media measure electroencephalography (EEG) signals or ERG signals generated from a device that presents a series of images on a timing cycle to a subject. The apparatus comprises a Central Processing Unit (CPU), Power Supply Unit (PSU), Random Access Memory (RAM), and a hard drive (HDD). The apparatus further includes at least one electrode and a photo-sensor like a photodiode for conversion of light into electric current. The CPU is operable with software for converting the EEG or ERG signals evoked from the visual stimuli to provide data and retrieving the status of EEG signals.
