Why do my eyes move like they do? Sudden jumpy movements, why can't they move smoothly without tracking something?
The movements of your eyes are controlled by a region of the brain called the cerebellum [2]. The cerebellum helps decide what gets priority treatment and what doesn't, and it works on what is effectively fuzzy logic [2]. It compiles thousands of sensory nerve inputs to decide on what actual sense you are conscious of [2]. And in the same way, it is sending thousands of nerve signals to muscles in order to get just the adjustment that you want [2]. That includes the movement of the six extra-occular muscles around each eye [2].  If you ask someone to look for something around a room, you will see that their eyes do not scan smoothly, but jump from spot to spot [2]. An area of the cerebellum called the flocculus is helping to control that process [2].
The term nystagmus is used to describe involuntary eye movements, which may be side-to-side, up and down, or rotary. [2] People who suffer from this condition often experience these movements when gazing at a fixed object in their peripheral view, or when watching objects moving at high speeds. [2] Oscillopsia is a vision problem in which objects appear to jump, jiggle, or vibrate when they're actually still. It stems from a problem with the alignment of your eyes, or with the systems in your brain and inner ears that control eye movements. [3]