Survival Reactions are subconcious reactions to perceived dangers, reactions we have usually no control of. They pop into our subconcious and control our body, without us even being aware of that occuring.
Survival Reactions are related to Fear, Amygdala, Fight-or-flight_response. As the Bene_gesserit#Litany_against_fear says, "Fear is the mind killer" - these reactions need to be controlled. There are ways to train yourself, if not to remove these reactions altogether, to at least increase the thresholds at which they kick in and recognize when they occur.
Survival Reactions are not always your friend... especially on a motorcycle. Their effects on motorcycle riding and racing are discussed at length in Keith Code's book A Twist Of The Wrist II.
Some of these reactions include: