A system for delivering electrical stimulation to alter a cognitive state of a user, the system comprising: a testing device configured to generate a user-specific testing phase biomarker indicative of high-performance or low-performance cognition, the testing device configured to: present a cognitive test to a user, wherein the cognitive test may include one or more stimuli, and require a respective one or more user responses; receive a response and a testing phase brain signal from the user; associate the response and the testing phase brain signal with a respective stimulus of the cognitive test; determine that the testing phase brain signal corresponds to one of: a high-performance cognitive state of the user and a low-performance cognitive state of the user; and generate a user-specific testing phase biomarker using the testing phase brain signal; a modulation device configured to: monitor a brain signal from the user; evaluate a cognitive state of the user by monitoring the brain signal of the user to identify the user-specific testing phase biomarker, wherein the testing phase biomarker is derived from the cognitive test performed on the user during a testing phase; and deliver stimulation to a brain of the user based on the evaluating step to steer the brain of the user towards a high performance cognitive state. a testing device configured to generate a user-specific testing phase biomarker indicative of high-performance or low-performance cognition, the testing device configured to: present a cognitive test to a user, wherein the cognitive test may include one or more stimuli, and require a respective one or more user responses; receive a response and a testing phase brain signal from the user; associate the response and the testing phase brain signal with a respective stimulus of the cognitive test; determine that the testing phase brain signal corresponds to one of: a high-performance cognitive state of the user and a low-performance cognitive state of the user; and generate a user-specific testing phase biomarker using the testing phase brain signal; present a cognitive test to a user, wherein the cognitive test may include one or more stimuli, and require a respective one or more user responses; receive a response and a testing phase brain signal from the user; associate the response and the testing phase brain signal with a respective stimulus of the cognitive test; determine that the testing phase brain signal corresponds to one of: a high-performance cognitive state of the user and a low-performance cognitive state of the user; and generate a user-specific testing phase biomarker using the testing phase brain signal; a modulation device configured to: monitor a brain signal from the user; evaluate a cognitive state of the user by monitoring the brain signal of the user to identify the user-specific testing phase biomarker, wherein the testing phase biomarker is derived from the cognitive test performed on the user during a testing phase; and deliver stimulation to a brain of the user based on the evaluating step to steer the brain of the user towards a high performance cognitive state. monitor a brain signal from the user; evaluate a cognitive state of the user by monitoring the brain signal of the user to identify the user-specific testing phase biomarker, wherein the testing phase biomarker is derived from the cognitive test performed on the user during a testing phase; and deliver stimulation to a brain of the user based on the evaluating step to steer the brain of the user towards a high performance cognitive state.