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What can we learn by measuring brain activity?

writer: HIGO, Katsuki (Ritsumeikan Global Innovation Research Organization, Senior Researcher) published: 2017-12

In recent years the measurement of brain activity has begun to be conducted in the study of various fields such as medicine, psychology, engineering, and economics. (If you thought, “Really? Economics?” then please look up the terms “neuroeconomics” and “behavioral economics.” In my own field of cognitive psychology, today brain activity measurement occupies an important position as a method of research. So what is it we are able to learn when we measure brain activity?

We can learn about the brain

It’s obvious, but one thing we can do is “learn about the brain.” We’ve learned, for example, that when we speak a part of the brain called “Broca’s area” is active, and that the hippocampus plays an important role in fixing memories. We can also examine how brain activity changes with illness and aging (Yokoyama and Watanabe,
These findings lead to clinical applications such as ideas for the treatment and rehabilitation of patients whose brains have been damaged by illness or injury. This is purely a personal opinion, but it seems to me that the majority of research using brain activity measurement conducted by psychologists is undertaken toward this end.

Psychology and brain activity measurement

Another aim of measuring brain activity is to learn about the “mind.” Here “mind” mainly refers to the cognitive functions such as remembering, thinking, and calculating. Cognitive psychology is a field of research that explicates human cognitive systems using a technique called behavioral experiment. For example, from an experiment that found a word with a meaning such as “bamboo” is easier to remember than a meaningless collection of sounds like “damboo,” we learned that we use semantic information and not only sound when we remember a word.
So why is measuring brain activity connected to clarifying the workings of the mind? Because by measuring brain activity we can learn more about information processing that occurs in our mind but cannot be understood by external observation alone. Here I will describe a technique called near-infrared spectroscopy (NIRS) as an example of a method of measuring brain activity. NIRS is a technique that makes it possible to see “when” in an experimental sequence the brain is active.
For example, one experiment measured brain activity when solving figure puzzles (Okamoto, 2008). In this experiment, the participants’ brain activity was measured as they solved figure puzzles while receiving hints over a period of roughly three minutes. The data ultimately obtained from a behavioral experiment would only include things like the percentage of accuracy and time taken to solve the puzzles. When brain activity is measured, however, changes in the participants’ brain activity during the three minutes they are solving the puzzles can also be seen. This brain activity data can provide a means of learning whether hints are effective, and whether receiving a hint changes how the participants approach a problem.
It is also assumed that the greater the cognitive load, or in other words the more you are using your brain, the more brain activity there will be. On this basis, brain activity can be used to learn how much cognitive difficulty people experience during a particular behavior (Kuroda, 2005). When someone has solved several problems, for example, it is surprisingly difficult for them to verbally explain which was most difficult, but by examining brain activity it is possible to determine how difficult different types of problems are.

Looking at brain activity alone isn’t very meaningful

When it comes to measuring brain activity, it is important to note that it is not as though “all we need to look at is brain activity.” The brain is an organ with complex workings, and just by looking at someone’s brain activity it is impossible to know what that person is thinking or feeling. In the two studies mentioned above, participants were also asked directly whether the presentation of hints was effective and which problems were difficult. We can say that brain activity data only becomes meaningful when combined with other types of data.

There are many things we can learn without measuring brain activity

Of course, there are many things we can learn even if we don’t measure brain activity. For example, if we conduct a well designed experiment the memory characteristic of “how many words can a person memorize?” and the memory mechanism of “we use not only sound but also semantic information when we memorize words” can be examined without measuring brain activity. And it can even be said that these are things that cannot be examined only by measuring brain activity. At first glance brain activity measurement may seem all powerful, but there are many things we cannot understand using only this technique. Brain activity measurement is not all powerful, but it can certainly be described as a powerful tool that has demonstrated its value in combination with other techniques such as behavioral experiments and questionnaires.


  • Kuroda, Y. (2005). Analysis of Brain Hemoglobin Changes in Solving a Calculation Problem : The Subtraction Problem. Bulletin of the Faculty of Education, 16, 37-50.
  • Okamoto, N. (2008). The Characteristics of the Concentration Changes of Hemoglobin in the Brain by Providing Clues during Studying. Annals of Educational Studies Osaka University, 13, 43-54.
  • Yokoyama, S., & Watanabe, M. (2007). Keyword psychology series 3: Memory, thought, and the brain. Shin’you sha.


Ritsumeikan Journal of Human Sciences


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Institute of Ars Vivendi. Ritsumeikan Univ.