Individual DifferencesPeople who behave in a socially deviant and apparently unintelligible manner should be considered abnormal because they do not agree with social conventions and do not do what is normally expected in society. The definition of abnormality determines an individual's mental state by studying the extent to which he or she follows the "unspoken" rules of society. However, this approach has some limitations. One problem is the idea that social norms change over time. What is acceptable in society today may have been incomprehensible in the past. For example, single women who became pregnant (i.e. outside of marriage) were considered social deviants and some were hospitalized in psychiatric institutions. Nowadays, it is much more common for single women to have children outside of marriage. The “statistical rarity” approach is based on the idea that certain behaviors are statistically rare in the general population. If very few people (2.145% of the population) exhibit rare behavior or thinking, then they are described as abnormal. Again, this approach also has limitations. The concept of statistical anomaly does not allow us to identify rare behaviors requiring treatment. The approach fails to make reference to desirability. Some rare behaviors are undesirable, such as anorexia, anxiety and many others. Yet other rare behaviors are highly sought after, such as low anxiety and genius. The “statistical infrequency” approach fails to provide a definition that shows that the rare behavior is undesirable and potentially harmful to the individual. The behavioral model indicates that individuals with mental disorders possess maladaptive behaviors, which have been learned. the individual to achieve major life goals, such as maintaining good relationships with other people or working efficiently. Most learning takes the form of classical conditioning or operant conditioning. Therefore, an appropriate form of treatment involves additional conditioning or observational learning that will help eliminate maladaptive behaviors that have been detected.