<P> While the Motivator - Hygiene concept is still well regarded, satisfaction and dissatisfaction are generally no longer considered to exist on separate scales . The separation of satisfaction and dissatisfaction has been shown to be an artifact of the Critical Incident Technique (CIT) used by Herzberg to record events . Furthermore, it has been noted the theory does not allow for individual differences, such as particular personality traits, which would affect individuals' unique responses to motivating or hygiene factors . </P> <P> A number of behavioral scientists have pointed to inadequacies in the need for hierarchy and motivation - hygiene theories . The most basic is the criticism that both of these theories contain the relatively explicit assumption that happy and satisfied workers produce more, even though this might not be the case . For example, if playing a better game of golf is the means chosen to satisfy one's need for recognition, then one will find ways to play and think about golf more often, perhaps resulting in a lower output on the job due to a lower amount of focus. . However, despite the effect on output, employees' job satisfaction (for example, measured by Herzberg's theory) is important for retention, which is critical in professions that experience shortages . </P> <P> Another problem however is that these and other statistical theories are concerned with explaining "average" behavior, despite considerable differences between individuals that may impact one's motivational factors . For instance, in their pursuit of status a person might take a balanced view and strive to pursue several behavioral paths in an effort to achieve a combination of personal status objectives . </P> <P> In other words, an individual's expectation or estimated probability that a given behavior will bring a valued outcome determines their choice of means and the effort they will devote to these means . In effect, this diagram of expectancy depicts an employee asking themselves the question posed by one investigator, "How much payoff is there for me toward attaining a personal goal while expending so much effort toward the achievement of an assigned organizational objective?" The expectancy theory by Victor Vroom also provides a framework for motivation based on expectations . </P>

Who proposed a two-factor theory that explains how motivator factors related to satisfaction