Perceptual control theory (PCT) approaches the behavior of living systems as though it were a phenomenon of control, and systematically assesses the variables that the individual controls using the Test for the Controlled Variable (TCV). PCT may be supported by the minority because the majority of behavior scientists, like most people, can miss the phenomenon of control as it is occurring. An earlier paper reported three studies of a behavior that was known to be a process of control because it had been explicitly instructed. In each case, most observers did not detect the control. Our novel extension of this study used live observation of ‘actors’ and ‘observers’. We tested in pairs 164 participants randomly allocated to each role. The actors completed a two-dimensional compensatory tracking task. To keep a dot at the center of a circle, the movements of a computer mouse needed to vary as the inverse of a disturbance pattern that was an inverted form of the word "hello" in script. The trace of their mouse movements was displayed on the screen – writing the word ‘hello’. As predicted, most observers missed the phenomenon of control; they inferred that the actor’s instruction had been to write ‘hello’, rather than to control the dot. In contrast, the actors reported that they had been keeping the dot in the circle and were unaware of having written the word. The TCV analyzes behavior by consistently identifying the controlled variable without relying on heuristic methods used by researchers that can be inaccurate.