EEG data from mental concentration task

This experiment has 20 subjects. Subjects asked to mentally concentrate on a target (see published article for more information) for periods of about 15 seconds. There are 4 verbal instructions given to subject by an automated computer program connected to a speakerphone: - The instruction is to wait until the experiment starts - The instruction is to relax - The instruction is to get ready as the trial is about to start - The instruction is to mentally concentrate on the target All the experiment is performed eye's closed. Relax periods last for about 9 seconds, are then followed by a period of 6 seconds where the participants is asked to "get ready" for the trial, followed by a period of 15 seconds of concentration. This sequence is repeated 20 times for each participant.