 2.4 EEG Recording and ERP Computation. ERPs will be extracted from EEG activity recorded from an electrode cap with AgAg-Cl- active electrodes at sixty-four scalp sites according to the 10-10 system of electrode placement, including: three midline sites frontal Fz, central Cz, parietal Pz; three left hemisphere frontal F3, central C3, parietal P3 and three right hemisphere frontal F4, central C4, parietal P4 scalp sites; and bilateral mastoid activity. Electrodes will be also placed on the mid-forehead and nose to serve as ground and reference, respectively. Bipolar recordings of horizontal HEOG and vertical VEOG electro-oculogram activity will be taken from supra-sub-orbital and external canthi sites, respectively. All electrode impedances will be kept below 5kohms. Electrical activity will be recorded with an amplifier bandpass of 0.1 and 30 Hz, digitized at 500 Hz, and stored on hard-disk for later off-line analysis. Stimuli and resulting triggers for ERP analysis will be generated by Presentation software Neurobehavioural Systems, Berkeley CA 2.5 Questionnaires. In order to assess clinical variables in SZ patients, as well as caffeine consumption, 2 questionnaires will be administered: 1 Psychotic Symptom Rating Scale PSYRATS. The PSYRATS is designed to quantify auditory hallucinations and delusions, both of which have been associated with consumption of caffeine; 2 Caffeine Consumption Questionnaire CCQ. Collects detailed information on caffeine consumption, including sources of caffeine e.g., coffee, cola, etc... and time period of caffeine consumption. As both of these questionnaires probe trait vs. state measures, they will only be administered once. 