Pleasure experienced in humour is not simply reinforcement due to performing a reaction followed by drive reduction. Gratification in humour is, primarily, in not performing a reaction that is not followed by reinforcement. At the operational level, humour is a close contact of two distinct, interfering reactions (humour as intervening variable). Deductive coverage of this empirical law by a broader theory is achieved by subsuming the contiguity of two reactions into a form of dissipation of reactive inhibition. This is also the main hypothesis of this work: humour is gratification caused by sudden dissipation of reactive inhibition (humour as hypothetical construct). According to Hull [6; 7; 8], each performed reaction leaves behind reactive inhibition – a striving not to be repeated. This striving is an unpleasant state, similar to fatigue, so that removing it represents reinforcement, pleasure. The contiguity of two different reactions (R1 and R2), i.e. the quick sequence of R1 and R2, is a form of realization of the striving for R1 not to recur, that is, dissipation of reactive inhibition of the reaction R1. In other words, R2 is a sudden rest from R1. The quicker the sequence of R1 and R2, the stronger is ‘the rest effect’. This is because reactive inhibition is caught at the very end of R1, at its maximum, and therefore sudden dissipation of such big amount of reactive inhibition is more reinforcing. A mechanism of putting R1 and R2 closer together is the association (of contiguity, similarity or contrast) through which a connection, i.e. mediation of R1 and R2 is achieved. Based on our main hypothesis, humor can be divided with regard to presence, i.e. absence of the mediating reaction. A type of humor which includes the mediating reaction, i.e. association, is wit (catchword, raciness), while the other type without the association is comedy (comics).