On the far left you are asleep. In order to function you will have increasing awareness.
Some anxiety is good and required, say for driving a car.
Peak performance occurs when anxiety optimnally alerts the resposes of the body. However as anxiety continues to increase it interferes with performance until at the far right you are paralyzed by anxiety. Students with test anxiety describe their minds going blank. Students with math anxiety are on the far right of the curve. The goal is to reduce anxiety and move students closer to peak performance.