Psychologists use the designations of Type A and Type B personalities when assessing the likelihoods of physical illness resulting from how individuals respond to different circumstances, particularly stressful ones. This system or process for determining and categorizing personality types dates to the 1950s, and become a standard test of how different categories of individual function both in a normal environment and under conditions of elevated stress. Patients or test subjects are surveyed for how they respond to different external stimuli and their responses are recorded and analyzed. Typically, Type A personalities are those who are more outwardly “driven” to accomplish a given task and to succeed at endeavors in which they engage. General characteristics of individuals with Type A personalities include higher levels of competitiveness and impatience with the methods of others, a greater tendency towards outward manifestations of hostility, a preoccupation with time and the requirement to meet deadlines, and an overall appearance of aggressiveness in approaching even mundane tasks. In short, Type A personalities are highly-charged individuals in contrast to Type B personalities, who are considered more relaxed in their approach to life and less prone to outward manifestations of stress and hostility.