While measuring your heart rate, stickers will be applied to your chest to measure your ECG or it will be measured by means of a kind of squeeze on your finger (pulse oximeter). If your blood pressure is measured during an examination, you will be given a band around your upper arm which will inflate and deflate for a while, just as it is sometimes done at a doctor's or hospital.
When your skin conductance is measured you will get two electrodes on two of your fingers, this device measures, as it were, the sweat reaction on your fingers.
With EMG measurements you get stickers on your face that measure your muscle tension in your face. For all these methods the electrodes only receive signals and do not send them out to your body. Often these type of studies are done in combination with EEG and eye-tracker research.
During the examination you may be connected to one or more of the above devices for some time, the exact duration depends on the specific study. During the course of the study, you will perform a "task" on the computer. This may look like a (simple) computer game or watching pictures or videos on the screen. How this task works depends entirely on the question and purpose of the research. You will be informed in advance.
In principle, you do not need to make any special preparations for physiological study However, you may have to make certain preparations for the specific study for which you have signed up. In that case you will have been informed of this by the researcher prior to the appointment.
In principle, anyone can participate in physiological research. Always take a close look at which target group is being sought for the research for which you are registering, and whether you belong to that target group.