Formation of conditioned reflexes to the simultaneous complex stimulus (light + tone) was studied in young kittens during the second and third months of their life. "Go-no-go"--paradigm was used. Kittens learned to differentiate between the complex stimulus versus its components. The rate formation of positive and inhibitory reflexes was compared in young kittens and adult cats. It was found that kittens were able to solve this task during the second and third months of their life. However, the formation rate of inhibitory reaction to different components of the complex stimulus increased between the second and third months.