This theory can account for individual differences as people have diff. view towards rewards and costs and so what is acceptable may not apply to others. For example, Argyle found that many women feel less satisfied when they are over-benefited in a relationship, whereas many males feel little dissatisfaction. Therefore, it becomes very useful in explaining extreme cases where some people in very unhappy relationship do not dissolve, yet those in mediocre marriages do- this is because the investment is high (e.g. children) and the alternatives are low (e.g. no money) and so people tend to stay (Rusbult).
However, the claim that people constantly strive for rewards as motivation to maintain relationship has suggested people are selfish and self-centred in relationships. Yet it may be true to the Western individualistic cultures which emphasises on personal interests, but may not apply to non-western collectivistic cultures. This is because they emphasise on group values and so personal selfish concerns become socially undesirable. Therefore these theories are only relevant to Western cultures (Moghadamm et al).
Another theory, the socio-biological theories, states that our behaviours are the result of evolution in order to max the chance of passing on the genes. This would mean all relationships are evolved to increase the survival of individuals and opportunities for successful reproduction. Buss suggested that women often seek older, successful men because these men can support them and their children; whereas men prefer younger women because they are likely to be more fertile than older ones. After successfully pass on the genes, we have to protect them so as to max the chance to pass on further. So we are evolved to form close families to protect our children as they shared genes with us. The closer the genes, the more we prepare to sacrifice to protect them. This is the kin-selection which suggests survival of an individual’s genes is ensured by helping close relatives to survive.
The claim for kin-selection is supported by Fellner & Marshall’s study who found that 80% of parents are willing to donate their kidneys to their children. This shows that people with the closest generic relationships (i.e. parents &children) are willing to sacrifice to protect each other for their survival, thus support kin-selection. Therefore, this theory has made the specific nature of family worldwide- the enormous resources and energy devoted to children- explainable. This means it appears to gain validity.
However, such validity is limited because it cannot explain other common relationships such as homosexuals and close friendships. If the claim that relationships are to reproduce successfully is true, it will not apply to homosexuals as they cannot pass on genes. Furthermore, Grajek found that women love their best friend more than their partners. This cannot be explained by this theory as friends outside relatives cannot help pass on genes and so should be as important as their partner. Grajek’s contradictory findings have made this theory insufficient to explain most relationships.
