Manage. Decis. Econ. 27: 95–101 (2006)
Haselton and Buss’ (2000; Haselton, 2003) error management theory can tell us why. Their theory begins with an observation, made earlier by others (Yamagishi et al., 1999), that decision-making under uncertainty often results in erroneous inferences, but some errors are more costly in their consequences than others. Natural and sexual selection should then favor the evolution of inference systems that minimize the total cost of errors, rather than their total number. For instance, if a man must infer the sexual interest of a woman whom he encounters, he can make two types of errors: He can infer that she is sexually interested when she is not (false positive or Type I error), or he can infer that she is not sexually interested when she is (false negative or Type II error). What are the consequences of each type of errors?
The consequence of a Type I error, thinking that she is interested when she is not, is that he would be turned down, maybe laughed at, possibly slapped in the face. The consequence of a Type II error, thinking that she is not interested when she is, is a missed opportunity for copulation and to increase his reproductive success. The latter cost is far greater than the former. Thus men should be selected to possess a cognitive bias which leads them constantly to overinfer women’s sexual interest.
Haselton and Buss’ error management theory not only explains previously-known phenomena, such as a laboratory experiment demonstrating that men, both as participants and observers, overinfer women’s sexual interest than women do (Abbey, 1982), or the Safeway fiasco, but also leads to two novel predictions. First, women should underinfer men’s romantic commitment to them, because the cost of a Type I error (thinking that a man is romantically committed to her when he is not, getting pregnant by him, then having him desert, and having to raise the child alone) is far greater than the cost of a Type II error (thinking that he is not romantically committed to her when he is, and missing an opportunity to form a committed romantic relationship with him). Second, men’s tendency to overinfer women’s sexual interest should not apply to their sisters, because men need to perceive their sisters’ sexual interest in men accurately, so that they can protect the sisters in case they encounter unwelcome sexual advances from men.