knee-jerk reaction. Fig. an automatic or reflex reaction; an immediate reaction made without examining causes or facts. With one of his typical knee-jerk reactions, he said no immediately, citing some moral argument that no one understood. See also: reaction.
What did you see when the patients head was rolled to the opposite side? In horizontal canal BPPV, you should have seen a direction change. When the horizontal nystagmus is geotropic, the BPPV is suspected to be canalithiasis, occurring on the side with the more intense nystagmus.
The horizontal axis of a graph is also known as the x axis. Typically, the horizontal axis describes a quantity that changes in a predictable fashion. In the case of a scientific experiment, the horizontal axis usually denotes the control variable. This variable is deliberately controlled by the experimenter in order to determine the effects that change has on other variables.