Scholars have identified two distinct ways of thinking. This “Dual Process Theory” distinguishes a fast, nonanalytical way of thinking, called “System 1,” and a slow, analytical way of thinking, referred to as “System 2.” In radiology, we use both methods when interpreting and reporting images, and both should ideally be emphasized when educating our trainees. This review provides practical tips for improving radiology education, by enhancing System 1 and System 2 thinking among our trainees.
Why Think About Thinking?
The human brain is a complicated instrument. Decades of research, from modular studies to the social sciences, have helped us understand how we learn and function. Research in cognitive sciences has taught us that “thinking,” eg, making decisions or solving problems, is not a single process. There are different ways of “thinking.” For example, analytical and nonanalytical ways of thinking have been distinguished and referred to as the “Dual Process Theory” in the literature . Both ways offer strengths and weaknesses and both are used by radiologists in their daily practice. Herein, we aim to review these two main forms of thinking, and more specifically we aim to show how thinking about “thinking” can make us better teachers as well as better physicians.
Two Ways of Thinking: System 1 and System 2
The two thinking processes described in “Dual Process Theory” are called System 1 and System 2, and they refer to a fast, nonanalytical way of thinking and a relatively slow, more analytical way of thinking, respectively . Although the theory describes two distinct systems, they are rarely used in pure form , and many clinical problems are solved using a combination of both. One may derive a hypothesis intuitively for example, but then proceed in an analytical mode to test the hypothesis. Some authors advocate that there is a cognitive continuum with the two systems representing the extremes , whereas others debate that the two systems run in parallel .
System 1 is described as an automatic and intuitive thinking process, primarily based on instantaneously noting similarities between something observed and prior examples stored in our memory. This process can be so fast we may not even notice that we were “thinking.” For example, chest radiologists seeing their 200th case of cystic fibrosis may immediately identify the disease on a new chest radiograph. This thinking process can also be described as pattern recognition . This fast form of thinking tends to be highly developed in experts . For example, a pneumothorax tends to be quickly recognized by an expert radiologist, not requiring any deliberation over other differential considerations.
System 2 is a deliberate and analytical thinking process. In System 2 thinking, we are reasoning to get to a solution, for example by weighing supportive and opposing evidence for one or multiple hypotheses. In contrast to System 1, System 2 thinking tends to be slow and easily recognized as active “thinking.” The pneumothorax case mentioned previously could also be approached with a System 2 way of thinking, for example when a first year radiology resident considers whether the line visualized represents a skin fold, a bone edge, or a pneumothorax. Such a leaner would probably analyze factors such as whether the sharpness and the course of the line fit better with one consideration or another.
Why Are Both System 1 and System 2 Important for Radiologists and Radiology Learners?
System 1 thinking can be time-efficient. When a number of similar cases have been encountered (ie, experience), System 1 often results in the correct answer, and the time and effort of a detailed analytical process can be avoided. However, this fast way of thinking is less likely to work in novel situations or for unusual cases .
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Errors Related to Each Type of Thinking
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Tips to Improve Your Teaching with System 1 and System 2 Thinking
How to Support System 1 Thinking
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How to Support System 2 Thinking
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When to Use System 1 and System 2 Thinking
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Table 1
Teaching Tips to Enhance System 1 Thinking and System 2 Thinking
Teaching Tips System 1 Thinking System 2 Thinking Show common variants Explain how to distinguish between normal and abnormal cases Show many different cases of a classic finding or disease Address a full list of specific findings in atypical cases and mimics Ensure trainees practice with a substantial number of prevalent disease cases, with feedback Teach an “approach” to indeterminate cases Provide access to less prevalent disease examples via teaching files Provide information about how helpful clinical and image characteristics are in reaching a valid conclusion Use Aunt Minnie’s, rules of thumb, and radiological signs as a shortcut to identifying classic diseases (with appropriate caveats) Teach using positive and negative predictive values and likelihood ratios, when available Teach your trainees when to “slow down” and use System 2 (ie, red flags)
Table 2
Examples of System 1 and System 2 Thinking in Radiology Education
Examples of System 1 Supportive Teaching Techniques in Radiology
Examples of System 2 Supportive Thinking in Radiology Teaching
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Conclusion
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