"You can't understand the human heart." This is why I continue my research.

Controlling your thoughts is more difficult than you might think. Especially when you're feeling down, you often get trapped in negative thoughts and can't escape them. My interest in psychology began in high school when I wondered, "Why do depressed people get trapped in negative thoughts?" and I went to university aiming to become a counselor. However, as I studied Psychology at university, I was drawn to the difficulty and fascination of conducting my own Psychology, and after much deliberation, I decided to go to graduate school that focuses on basic research rather than clinical practice. In particular, I believe that the phenomenon of "getting trapped in negative thoughts," which I initially focused on, is deeply related to the exacerbation of depression, and I have continued to research this phenomenon from the first research project I planned myself as an undergraduate to the present day.

Our research has gradually revealed how depression and being trapped in negative thoughts are related. Here, we will introduce some of our findings. Thought suppression is the process or effort to remove thoughts about a specific subject from one's consciousness. Normally, thought suppression is properly achieved by using distractions to shift attention to something else, but we found that depressed people repeatedly think about the thoughts they are trying to get rid of, even when they try to distract themselves. So why are depressed people unable to effectively distract themselves? I focused on the mental state during distractions and conducted further experiments. I found that there was a difference in the strength of the conscious effort to "not think" during distractions between depressed and non-depressed people. People with mild depression found that their conscious effort to "not think" weakened when they engaged in distractions, but people with severe depression maintained the conscious effort to "not think" even during distractions; in other words, they tended to continue thinking "I'm not thinking." The conscious effort to "not think" can, if too strong, trigger the recall of the very thoughts being suppressed. Therefore, the tendency of depressed individuals to continue thinking despite trying not to think, as shown in the previous experiment, is thought to be a cause of being trapped in negative thoughts. This state of being trapped in negative thoughts is sometimes called rumination, and investigating how rumination relates to depression and thought suppression has been my main research topic to date.

While continuing my research on depression, I have recently also been studying various everyday phenomena. For example, even when we are trying to concentrate on something, our attention often wanders to other things. This phenomenon is called mind wandering, and it is said to occur 30 to 50 percent of the time we are awake. To investigate why and when mind wandering occurs, I have previously conducted research such as examining the state of students during classes and investigating mind wandering in daily life by sending notifications to smartphones. Currently, I am conducting research to investigate how emotions such as thought suppression and depression are related to this phenomenon.

In addition, I often collaborate with students in my seminars to research everyday phenomena based on topics they are interested in. I teach a course for students who are new to Psychology, and perhaps because I sometimes discuss romance in class, many students are interested in themes related to love, such as human attractiveness, infidelity, and infidelity. In particular, many students are interested in the relationship between color and attractiveness, and every year we conduct research together, aligning it with the students' interests. For example, we have tried to recreate the phenomenon of red making people appear more attractive (romantic red), and have investigated whether this phenomenon occurs not only with real people and photographs but also with illustrations. I have also investigated how fan activities related to idols are related to mental health and self-esteem, based on an idea from a student who is passionate about their favorite idol. I have also investigated whether the attributes of an idol (gender, occupation, whether it is 2D or 3D, etc.) are related to rejection of people who like the same idol (so-called "same-fan rejection") and a sense of camaraderie. I myself have no experience actively participating in fan activities and don't have much knowledge about them, so I will bring together the students' real-life experiences and knowledge, along with relevant academic research, and gradually shape the research through collaborative work.

These experiences remind us that countless research ideas exist in our daily lives, and that both my students and I already possess them. I believe it's essential for me to always be mindful of this, and something I want to convey to my students: having an interest in many things, cherishing and carefully considering anything that piques your curiosity, and having a broad foundation of knowledge and methodologies to nurture these research ideas. The last point, in particular, is often considered tedious and unwelcome, but I believe it's extremely important.

I think this is a path everyone takes when learning anything, not just Psychology, but the first thing I realized when I started studying Psychology was that "you can't understand the human mind." I have some experience researching depression, but what I have been able to uncover so far is only one aspect of it. There are many variations of depression, and I realized for the first time through studying and researching psychology that these are influenced by various factors such as what kind of event triggered Psychology, which I thought I understood because I also have one. At the same time, I began to doubt that the minds of others, which I had taken for granted were the same as mine, might actually be completely different. From then until now, I have continued to explore relevant prior research, formulate hypotheses, and verify them using data obtained from experiments and surveys, thereby deepening my understanding of depression, which I did not understand well. Psychology is often associated with the expectation of flashy results, such as being able to read people's minds or manipulate others at will. However, in reality, I believe it is a painstaking process of inquiry, gradually advancing our understanding of the often-mysterious human mind. I find this fascinating, and I believe that this accumulation of knowledge will lead society in a better direction. The knowledge we steadily accumulate about depression can be used to refine intervention methods for depression, and it can also lead to a better understanding of the physical and mental effects that depression has. It may also help to dispel misconceptions about people prone to depression. I would like to continue my research in the hope that it will alleviate, even just a little, the difficulties that depression brings to life.