The purpose of biofeedback is to subjects a) control their internal processes b) understand how fear holds them back c) determine whether they are sick d)manipulate computers without a keyboard

The purpose of biofeedback is to help subjects "control their internal processes".

Biofeedback is a kind of treatment that utilizes sensors joined to your body to gauge key body capacities. Biofeedback is expected to enable you to take in more about how your body functions. This data may assist you with developing better power over certain body capacities and address wellbeing concerns.  

This feedback causes you center around rolling out inconspicuous improvements in your body, for example, loosening up specific muscles, to accomplish the outcomes you need, for example, decreasing agony. Generally, biofeedback enables you to utilize your musings to control your body, frequently to enhance a wellbeing condition or physical performance.