The direct rewards associated to such areas then have a sexual nature for men, and a psychological one for women
The dynamic process through which the couple bond builds on or not as the interaction among possible partners unfolds is called the tie-up cycle (TU-C). In its natural direction, the cycle moves counter-clockwise and contemplates a sequence of direct and indirect rewards for each partner, which, if provided in the correct order, make the process self-catalytic, and thus driven by self-reinforcement through the cooperation among the partners until the formation of a stable couple bond ( Figure 1 ). However, it is possible that the unfolding of the interaction threatens or precludes the completion of the cycle, its iteration or the momentum of such iteration, or leads to a simulated path for one or both partners, up to the possibility that one of the partners steps out of the cycle altogether, breaking it down. These other possibilities may lead or not to the formation of a short-term or long-term couple, but without a self-catalytic drive. The couple bond will therefore not be self-reinforced by the within-couple interaction, and it will remain intrinsically fragile even if it is formed in some way. The fact that the partners get tied-up at some point of the process is a precondition for self-catalysis, but it is always possible that even tied-up partners fail for some reason to move along the cycle in the correct way.
Representation of the tie-up cycle. Male vs. Female hemicycles, psycho-emotional vs. sexual spheres. M-AA = Male Active Area; M-RA = Male Receptive Area; F-AA = Female Active Area; F-RA = Female Receptive Area. Red arrows are direct rewards, blue arrows are indirect rewards.
Designing experimental tests to establish which theory better describes the dynamics of couple formation, and in particular discerning whether or not the incentives behind such dynamics are sexually dimorphic, will be an important line of future research
Let us see now why the tie-up cycle has a characteristic direction, and why moving along it is related to the tying-up of the two partners. In the TU-C sequence, the generation of indirect rewards (that is, those associated to the RAs) precedes, both for men and women, that of direct rewards. This reflects the disadvantage of the woman as to the risks related to the mating. In particular, as it is possible to step into the TU-C from whatever position (that is, from any of the four areas of the graph), this implies that men can choose to enter from their M-AA, thus leaving behind their M-RA that would expose them to the possibility of being tied-up. If they are just aiming for a sexual reward, they can now simply move along the cycle counter-clockwise toward the (sexually orientated) F-RA. For women, however, it is the RA that is characterized in sexual terms, and consequently, female sexuality is always connected to a possibility of being tied-up-and the fact that the sexual F-RA precedes the psycho-emotional F-AA along the cycle inevitably entails a psycho-emotional involvement of the woman, that is, of her F-AA that receives the signal of the excitement of the F-RA in sexual intercourse due to the deployment of the flow of rewards along the TU-C. One could regard the characteristic mating-related interaction pattern of the TU-C as an alternative conceptualization of the dynamic process leading to the possible formation of monogamic couples with respect to existing theories, such as the stimulus-value-role theory . In the stimulus-value-role theory, the process of couple formation is not driven by sexually dimorphic incentives, which are a central feature of the tie-up theory, but follows a different, partially conflicting logic.