Cognitive psychologists use the term decision making to refer to the mental activities that take place when choosing among alternatives. Typically, decisions are made under conditions of some uncertainty, and dealing with this uncertainty appears to be a major factor in the way people approach making decisions. It is argued by psychologists that "good" decision making cannot be measured by the success of the outcome – luck, for example, often plays a large role. Therefore the benchmark of a successful decision is often considered to be its rationality. Winterfeldt & Edwards (1986) defined rational decision making as "to do with selecting ways of thinking and acting to serve your ends or goals or moral imperatives, whatever they may be, as well as the environment permits." Rational decision making requires the individual to gather information about their decision as carefully as possible under the circumstances. It also means looking at evidence that supports the person's initial inclinations, but also the factors which do not.
It is suggested that the increased social, economic and technological significance of decisions in modern society have resulted in influencing the plethora of research and psychological approaches to their study. Some decisions are very personal, where the individual takes the major responsibility, for example in career choices and matters of relationships, family life, health and education. Other types of decisions rely heavily on the advice of others, for example, doctors diagnosing patients. Decisions are a fundamental part of society and democracy, for example voting for the politicians who lead the country, or deciding the outcome of a criminal case as a member of a jury. Within the corporate world, decisions are made about ways to increase profit and productivity through investment, research development, and resources.
Several phases or tasks are encountered by the person who may be engaged in a decision making situation, regardless of the complexity. These phases may occur in any order and can be skipped and returned to at a later point in the process. Setting goals is a primary phase, as they often turn out to be the reasons for the decision maker's thought process. Goal setting allows the individual to understand their plans for the future, principles, values and priorities. The decision maker needs to develop answers or needed results to questions such as "what am I trying to accomplish?" Prior to a final decision, the individual needs to gather information to understand the various options available. Some decisions may just have two options — to take particular course of action, or not. For others, several options may be available. In all circumstances, the person needs to establish the likely consequences both short and long term – such as if anybody else will be affected; considering if the effects change over time; and whether one choice will obligate the decision maker to other decisions or plans. The decision maker will take a holistic view over various actions and consequences of potential decisions.
When faced with complex decisions, individuals need a way of pulling together all their information. This is especially true when there are multiple options and considerations to take into account. The person needs to determine or invent a way of managing this information. Once all the information is gathered and structured, the decision maker needs to make a final choice from the set of options they have concluded. After the final decision is made, the evaluation stage reflects upon the entire process. Here the person can identify the areas of the process which may stand improvement as well as those that can be used again in the future. People differ in the way they approach decisions. Psychologists use the term individual differences to refer to stable, enduring traits or characteristics that change the way a person approaches a task, sets their goals, gathers or organizes information, makes a final decision and evaluates the process. It appears these differences may stem from temperament or personality. Differences in decision making may be developmental — whereby children are described as making quick, impulsive decisions and adolescents are prone to taking unwise risks. It is also suggested that experience and practice in decision making in certain fields may change or strengthen their approaches.