Sources of Power

Sources of Power: How People Make Decisions

Author: Gary Klein



This book is a comprehensive review of naturalistic decision making (NDM), the use of experience to make judgments in field settings. It describes how experts make decisions in dynamic situations characterised by time pressure, high stakes, inadequate information, ill-defined goals, and poorly defined processes (page 4). The book shows how professionals such as firefighters, intensive care workers, and military commanders make critical, split-second, judgments by relying on what the author calls ‘the sources of power’. These are the powers of intuition, mental simulation, metaphor and storytelling. He illustrates how each of these contribute to decision-making: ‘the power of intuition enables us to size up a situation quickly. The power of mental simulation lets us imagine how a course of action might be carried out. The power of metaphor lets us draw on our experience by suggesting parallels between the current situation and something else we have come across. The power of storytelling helps us consolidate our experiences to make them available in the future, either to ourselves or to others’ (page 3). Because perception is at the core of these processes, he has also named this recognition-primed decision making (RPD).



The author’s extensive studies of field experts show that they make decisions, not by choosing serially from a set of options (which novices do), but by picking the first option that comes to their mind. ‘They did not have to compare options; …even when faced with a complex situation, the commanders could see it as familiar and know how to react’ (page 17). The experts are proficient at recognising important cues, typical patterns, anomalies, fine differences, and the bigger picture. The first option they consider in a novel situation is therefore frequently the correct one because their vast experience makes the setting feel familiar. This, the author says, is what constitutes intuition: ‘recognizing things without knowing how we do the recognizing‘ (page 33). Intuition does not rely on a specific memory but on ‘…a large set of similar incidents all blended together’ (page 34). This explains why experts are often unable to explain why a situation felt familiar to them.



The book elaborates on the other sources of power and explains their importance in decision-making. Mental simulation for example is ‘…central to decision making …because we keep finding it in expert performance’ (page 51); it is however vulnerable to biases such as the de minimus explanation and the garden path fallacy. He describes a version of mental simulation called pre-mortem; this identifies flaws in a plan by simulating the different ways the plan may fail (page 71). The book refers to the power of stories as’…the method we have found most powerful for eliciting knowledge’ (page 189). In later chapters he addresses the ‘power of the team mind’ with emphasis on integrated identities, team cognition, and communication of intent (the power to read minds). He lists eight types of critical information which good teams need to transmit effectively (page 229).


The author finally discusses the causes of bad decisions, attributing this to inexperience and lack of information. He is critical of the value of rational analysis in the field setting and does not ascribe poor decisions to faulty reasoning or biased thinking. He says intuitive decision-making could be taught using the techniques experts use to learn-perception, deliberate practice, and timely feedback (page 104). The experience of experts may also be captured and used for training by the process of cognitive task analysis. Simulation may also help expand the experience-base of novices (page 42).” target=”_blank”>

Gary Klein talking about expertise


Is this science? the author asks at the end of his book. The author’s studies are fundamentally descriptive and qualitative, and most of his conclusions are inferences from observations in the field. This is an important point because most psychological studies of decision making are laboratory-based. The author however makes a very strong case for his arguments and does this in a thrilling way. He explains his research clearly and gives illustrative examples from diverse professions, including healthcare. I thought his conclusions were reasonable and support his view that intuitions are important in decision making; this view contrasts with the general assumption that heuristic and biases are detrimental to effective judgments.


The author makes a cogent case for intuitive decision making and he supports this with good evidence. The book teaches valuable lessons on the importance of experience in decision making and I recommend it.


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