Creative processes (creativity) exist in all aspects of our lives, including science, technology, education, and culture, and serve to solve problems and enrich our lives1. When faced with a problem, we attempt to solve it by accessing our memories and information from the outside world2. We deductively formulate hypotheses based on our experiences and inductively test them to reach a solution3. However, complex or new problems that have not been experienced previously may not be solved easily. In such cases, we actively access our memories and information from the outside world, motivated by problem solving. By shifting perspectives, we recognize strange or surprising events and generate hypotheses through abduction4. In this regard, the process of “insight,” in which sudden inspiration is obtained, is necessary. When an idea obtained through insight is starkly different from what was previously thought, positive emotions such as interest and surprise are generated5. Such an experience is called the “Aha” experience or the Eureka effect6. In the scientific field, the positive emotion of an “Aha” experienced with a new discovery, which overturns conventional wisdom, increases the spirit of inquiry for further discovery7,8. In the field of technology, the “Aha” experience with a major shift in perspective upon developing a new technology triggers the next technological innovation. Regarding the process of insight, the fluency theory9 explains that the reason for positive emotions during this process is that cognitive processing of information becomes smoother, leading to a heightened sense of confidence when new information is recognized, namely imbuing a sensation of being certainly convinced. The pleasure interest model of aesthetic liking (PIA) model10 divides human cognitive processing into unconscious automatic and conscious controlled processing. When people can recognize information smoothly during automatic processing, they have high fluency and experience pleasant feelings of pleasure; however, when they cannot do so, they have low fluency and experience unpleasant feelings of displeasure. The emotional response is caused by the disfluency reduction to the information, i.e., the resolution of the uncertainty of recognition, which is a process of control to understand the information further. When disfluency reduction occurs for an information, positive feelings of interest are also generated for other information. Contrarily, when disfluency reduction does not occur, the information cannot be recognized, and a negative emotion called confusion is generated. In the insight process, the positive emotion of interest is considered the positive emotion of the “Aha” experience when other information is recognized by changing the perspective.
Prediction about the emergence of interest from the free energy model
Our group proposed the general framework of a mathematical free-energy model of emotional valence to explain emotions such as pleasure with recognition of information and interest with shifting perspectives and recognition of other information11. Based on the minimized free-energy model of emotion12 and the PIA model10, we formulated the change in the fluency of information processing in unconsciously automatic and consciously controlled processes when recognizing information from one perspective and from another perspective as an increase or decrease in free energy.
Consider an instance of observing the hidden Dalmatian dog illusion. At first glance, a cluster of black dots is perceived. This initial perception is an unconscious, automatic process that results in pleasure due to the recognition of a familiar pattern. This process is characterized by high information processing fluency and decrease in free energy (ΔFi in Fig. 1). If this image is attempted to be viewed from another perspective, the process shifts to conscious and controlled, leading to reduced fluency in information processing and increased free energy. If one cannot make sense of another perspective, one might feel negative emotions, such as confusion. However, upon deducing that the image represents a Dalmatian dog, the inefficiency in processing the new pattern is resolved. This resolution, known as the “disfluency reduction,” decreases the free energy again and leads to an “Aha” experience, which is accompanied by a positive emotional response. We interpret this emotion as that of interest.
In our model, we quantified the amount of reduction in free energy (ΔFj in Fig. 1) upon the recognition of something from another perspective. We calculated this reduction based on the following factors: how certain we were about what we first recognized (si in Fig. 2, i.e., prior belief uncertainty of the first recognized information: the variance of the prior distribution [pi(x) in Fig. 2, i.e., a prior belief of first recognized information]), how certain we are about another recognition (sj in Fig. 2, i.e., prior belief uncertainty of another recognized information: the variance of the prior distribution [pj(x) in Fig. 2, i.e., the prior belief of another recognized information]), how different the prior belief of another recognition is from the first one and recognized information later i.e., the recognition distance.
The recognition distance is the ratio of two distances, where the first distance is between the recognized information later (p (y|x) in Fig. 2) and the prior belief of another recognized information (δj in Fig. 2). The second distance is between the prior distribution (µij in Fig. 2)
We used numerical simulations to understand how the recognition distance affected the amount of free energy reduction. In other words, we studied how expanding our understanding of an information (disfluency reduction) depended on how much we ought to change our perspective.
We predicted that disfluency reduction would be greater for larger recognition distances when the belief uncertainty for the first recognized piece of information (si) was larger than that for another recognized piece of information (sj). Therefore, in the hidden Dalmatian dog illusion, when our prior beliefs are highly uncertain, such as the set of black dots that we initially recognized (i.e., the arrangement of the dots is random), and when our prior beliefs are highly uncertain, such as another recognized Dalmatian dog (i.e., we are familiar with the features of the Dalmatian dog), a larger recognition distance (i.e., we recognize the Dalmatian dog only from the observed picture) causes more surprise and interest once the Dalmatian dog is recognized.
However, this mathematical model predicts that the amount of disfluency reduction is larger when the uncertainty of belief in another recognized information (sj) is larger than the uncertainty of belief in the first recognized information (si), when the recognition distance is smaller. This means that when recognition switches from information with certain beliefs to information with uncertain beliefs, the change in recognition is easier and more interesting. The predictions of this mathematical model explain the shift from existing solid knowledge (i.e., common sense) to unprecedented and uncertain knowledge (i.e., ideas that nobody has thought of before) in the creative process of science and technology. The model predicts that, in this case, the easier it is to change recognitions (i.e., the less surprising another idea is), the more positive feelings of interest arise. The fact that less unexpectedness is more interesting differs from our intuition and is based on our experience. However, if we look at this situation from a different perspective, the recognition distance is proportional to the distance between the observed information and the prior distribution of the newly recognized information. Furthermore, a small recognition distance indicates that another idea is far from the existing solid knowledge. In other words, an idea may be interesting if nobody has ever thought of it before and if it is easy to recognize and accept as another idea. Therefore, the predictions of our model are important for understanding processes that are essential for creativity, such as abduction.
This study aims to demonstrate the biological validity of the predictions of a mathematical model that explains the emotions involved in shifting perspectives and recognizing another information. Specifically, by measuring human brain functions, we tested the prediction that a smaller recognition distance (i.e., easier recognition) would produce more positive emotions such as interest, when shifting from recognition based on certain beliefs to recognition based on uncertain beliefs.
Neuroscientific research related to interest
A functional brain measurement study investigating the transition of emotion and brain processing in the automatic and deliberate process showed that during preference judgments for human faces, rapid automatic processing occurs in the nucleus accumbens (NAC), followed by slower control processing in the orbitofrontal cortex (OFC) and insula13. Additionally, neuroimaging studies of positive emotion14–17 have shown that the anterior cingulate cortex18–20, amygdala21–25, hippocampus, striatum, caudate, and putamen are involved in positive emotions. Furthermore, hippocampal and parahippocampal activity during the presentation of an interest question26 are activated during positive emotions, which facilitate subsequent memory recall27, suggesting that memory retrieval and consolidation are facilitated during positive emotions such as interest.
The purpose of this study is to analyze the brain activity related to subjective interest and positive emotions associated with changes in the recognition of information, as well as to verify the validity of model predictions based on the free-energy model of emotion. We experimentally created a situation wherein participants shifted from certain recognition to uncertain recognition by watching card magic, namely a trick where the objective is to determine the position of the target card, and experimentally manipulated the size of the recognition distance by the difficulty of recognizing the card magic technique (the trick). Brain activity during the task was measured using functional magnetic resonance imaging (fMRI), and the aforementioned brain regions were analyzed as the regions of interest (ROI).