How many signaling systems are human? Who developed the theory of signaling systems? What are the differences between the systems?

1) two signaling systems: the first and the second;
2) I.P. Pavlov;
3) unlike the first signaling system, the second provides abstract thinking, analysis and synthesis of information arriving in the form of symbols is associated with the function of speech.

Remember: The process of learning a person lasts a lifetime. The value of the same knowledge for different people may be different, it is determined by their individual characteristics and needs. Therefore, knowledge is always needed at any age and position.