Method and apparatus are provided for use in conducting an electroencephalographic (EEG) test where the apparatus includes a headset suitable for placement on the head of a subject to be tested. A plurality of electrodes are mounted on the headset at pre-determined positions about the headset. The electrodes are preferably mounted to the headset by the use of a resilient material, preferably a resilient wire or plastic mesh which is bonded to both the electrode assembly and to the headset.Each of the electrode assemblies include a separate air cylinder for displacing the electrode in the direction of the subject's head upon the application of additional air pressure into the cylinder. A bellows arrangement is provided within each air cylinder for effecting displacement of the electrode.Means are further provided for dispensing a predetermined amount of an electrolytic material from an external source of electrolyte, through the electrode, to the point of contact between the electrode and the subject's head.