Imagine that you are presented with a young man who has short, brown hair. He is of average build, around 20 years old, and is dressed smartly in a grey suit, white shirt, and a tie. His shoes are dress shoes but are scuffed. If you were asked to describe what this person is like you may assume that he is a young student or recent graduate looking for employment; perhaps he is attending a job interview. How did you come to this decision? Psychological research has demonstrated that we form judgements about people quickly, at least at first and often without realising it, and from these we form our impressions and make inferences about the person’s character. We do this using fast, heuristic processes. That is, we use ‘cognitive rules of thumb’ to form our initial judgements the majority of the time, and these judgements go on to influence our decisions: what do we think about a person and what we will do about it.

These heuristic processes are the result of evolution over the years and allow us to manage the vast amount of information that our senses take in from our social and environmental surroundings. Indeed, research has shown that, in most decisions, we rely on between 3-7 cues (pieces of information) to form judgements or make decisions about something. This decision making style is advantageous and relies on the person’s memory, the context they find themselves in, and their past experiences. While this fast decision making style is advantageous in terms of time and efficiency in the way that the human brain’s processing capacity is used, it may also leave the decision made prone to errors, or ‘biases’ in judgements made.

“This decision making style is advantageous and relies on the person’s memory, the context they find themselves in, and their past experiences”

To illustrate, imagine now the young man in his grey suit and somewhat scuffed shoes. However, this time imagine him in the context of a courtroom and you as a juror (or as the judge if you prefer), tasked to form judgements and make decisions about him. The young man is accused of assault to bodily harm. Now, rather than a young graduate seeking employment and wearing attire to impress an interviewer, you may be attributing his choice of clothing to the desire to look ‘respectable’ for the court. His scuffed shoes perhaps belie a lack of care over possessions, rather than a lack of funds to buy ‘interview shoes’ as in the previous example. You are perhaps imagining what he may be like in his normal day to day attire and forming judgements about his character. This is normal, and the result of fast, heuristic processes. However, in such an important context, one would hope and expect that the people in charge of making decisions about a person’s future would be less likely to rely on these heuristic processes to make decisions; that they would be rational and objective. Certainly, there is a slower, more ‘rational’ decision processes that humans use (though less commonly than heuristic processes) when decision difficulty or the importance attributed to a decision is high.

Interestingly, however, psychological research has shown that this is not always the case. For instance, a recent paper exploring the decision making of court judges found that the likelihood of a prisoner being granted parole was influenced by when the judge last had a break during the court day, with fewer parole decisions being granted by judges who had not had a recent break1. Another study indicated that important, life changing, decisions are not always made using rational decision making was that by Dhami and Ayton in 20012. This research found that, across a wide range of cases, judges relied on one or very few cues to come to their decision. This is in conflict with the due process expected in such decision making situations.

Psychologists and others researching the psychology behind decision making have theorised for decades that people make decisions using a ‘dual process’ model.  While the terminology and exact details differ slightly across different theorists’ dual process models and theories, the majority of theories propose that human decision making is composed of two related systems: a fast process and a slow process; whose use depends on the specific decision and individual making the decision. Again, across the dual process models of decision making, there is a general consensus that the majority of people, the majority of the time, use the fast decision making process to reach their decision.

One of the most recent and generally accepted dual theories of decision making was proposed by Prof Daniel Kahneman, Nobel Laureate and often credited as ‘the Father of Decision Science’, in his book ‘Thinking Fast and Slow’3. Kahneman’s theory simplifies much of the overly-academic, jargon filled models that existed previous, drawing on the most important and universal features of these models.

He proposed that we make decisions using two Systems: System 1 and System 2. System 1 is fast; the system that we use the majority of the time and which relies on emotions, intuition and heuristics. System 2 is a slower process, which we use when deliberating over a choice or comparing options; it is sometimes referred to as more ‘rational’ than System 1, but this does not make it more effective at making the correct decision. Indeed, while it is easy to consider the two systems as running parallel to each other, they are better considered as being related, with the decision maker able to use both systems to inform their decision making at various stages of the decision process.

“What is important, though, is to recognise the benefits and strengths of System 1 decision making: it has evolved to assist human decision making; to make it efficient and effective most of the time.”

It is therefore not a simple task to dictate what the ‘best’ way to make a decision is, or to identify how best to inform and guide decisions. What is important, though, is to recognise the benefits and strengths of System 1 decision making: it has evolved to assist human decision making; to make it efficient and effective most of the time. System 2, on the other hand, is more aligned to objective, evidence based decision processes required in complex and modern decision making situations (e.g., diagnostics, police decision making, court decision making).  It is therefore not likely to be advantageous to attempt to replace one system with the other, but instead to attempt to improve decision making by first, supporting natural decision making processes (supporting the use of System 1 processes, for example, rather than attempting to vilify and remove it completely) and encouraging the consideration of wider information and deliberative decision making (i.e., using System 2), through the use of easy to use, appropriate to context and fit for purpose decision making support tools/materials. Finally, it will become increasingly important for academics to work with non-academic groups for whom the wealth of research may be beneficial (e.g., public sector and industry decision makers) to facilitate the appropriate use of the theories to improve real practice.


1. Danziger, S., Levav, J., & Avnaim-Pesso, L. (2011). Extraneous factors in judicial decisions. PNAS, 108(17), 6889-6892.

2. Dhami, M. K. D., & Ayton, P. (2001). Bailing and jailing the fast and frugal way. Journal of Behavioral Decision Making, 14(2), 141-168.

3. Kahneman, D. (2011). Thinking, Fast and Slow. New York: Farrar, Straus and Giroux.

By Dr Jennifer Murray

CPsychol, PgC, BSc(Hons), Edinburgh Napier University

Dr Jennifer Murray is an associate advisor to Essenta.

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