In recent years, we have seen an exponential increase in interest in studying insight and creativity. Some creative ideas come to mind gradually, but others emerge as sudden flashes of inspiration. What causes these fascinating moments when – unexpectedly, and to our surprise and delight – a marvelous new solution emerges into consciousness? This is the wonder of insight that the chapters in The Emergence of Insight have described efforts to understand and explain. Although solutions reached via insight may be less common than more routine or step-by-step analytical solutions, the Aha! experience seems ubiquitous, familiar to all, and easily recognized. But what is an insight? Understanding insight itself presents an ill-defined problem that is yet to be solved.

Perspectives on how to define, operationalize, and measure insight have evolved due to developments in theory, methodology, and technology. Research on insight can be broken into several waves. In the first wave, Gestalt psychologists introduced the concept of insight as a discontinuous form of learning and problem solving that arises from changes in one’s global representation of a problem, in opposition to contemporary associationist views. In the second wave, psychologists examined insight in deliberate contrast with analytical problem-solving and found that insight involves nonreportable mental operations leading to a discrete, all-or-none availability of representational change. In the third wave, thanks to advances in behavioral methods and neuroimaging technology, cognitive neuroscientists began to examine how insight occurs in the brain with the goal of studying the neural states that co-occur with and precede insight to better understand its cognitive mechanisms. The advances made during these initial waves enabled the proliferation of research on insight over recent decades and inspired new discoveries. This chapter provides a brief retrospective on the first two waves of insight research and a more in-depth overview of the third wave of research on the cognitive neuroscience of insight, and ends by discussing current and future directions in insight research

In this chapter, we argue that differences in problem-solving experiences can be traced to differences in the activation of brain structures involved in the unconscious processing of information (what we refer to as “the backstage”). Scientists commonly distinguish between two major types of problem-solving experiences: via insight and via analysis. Three properties are often mentioned when describing how insight solutions differ from analytic solutions: (1) Solvers are unable to report much of the processing that leads to the solution which comes to mind in an off–on manner; (2) Solvers experience their solutions together with a feeling of pleasure and reward; (3) Solutions via insight feel correct and they actually are. This is captured by a distinctive response: the Aha! This chapter focuses on these three properties and argues that unconscious processes are important for problem-solving in general, but especially important for insight experiences because most of the processing that leads to the solution happens below awareness. It also argues that the positive affect associated with insight serves an adaptive function.

Where do insights come from? What causes those moments when, unexpectedly, a marvelous new idea flashes into consciousness, possibly accompanied by feelings of surprise and delight? Sudden insights are rare, yet everyone appears to be familiar with the experience that may be alternatively described as an “Aha!” or “Eureka” moment: a sudden realization, an epiphany, illumination, revelation, or satori. The ideas resulting from insight experiences range from mundane to historic. Insight is defined not so much by the importance or significance of the content produced, but rather by the cognition and the phenomenology of the event. At its core, the insightful solution process begins with the solver holding an incorrect representation, and ends (if successful) with a nonobvious solution. But there is much more to know: What is insight, and how does a solution emerge unexpectedly into awareness? Is there a set of steps, a pathway that leads to insight?

One of the major achievements of psychology in the twentieth century is the establishment and implementation of standard measures of human intelligence. The use of these measures yielded a large body of research as well as many controversies and criticisms (for review see Nisbett et al., 2012). The relatively recent development of structural and functional brain imaging techniques led to attempts to identify the neural correlates of intelligence, as well as to the use of intelligence testing as a diagnostic and prognostic factor within clinical populations. Different syndromes are characterized by a unique pattern of performance on standard intelligence tests, with specific profiles reported for patients with developmental disorders (e.g., Down syndrome, autism spectrum disorder), for neurological and neurodegenerative disorders (e.g., epilepsy, multiple sclerosis, Parkinson’s disease, Alzheimer’s disease), and for acute neurological trauma (e.g., traumatic brain injury and stroke. See Hamburg et al., 2019; Wechsler, 2008a). In this chapter, we will highlight the clinical implications of studying intelligence in adults with traumatic brain injury (TBI), which has been a central research interest for our group over the years. When appropriate, we will also provide additional examples referring to other clinical populations.