On RIKEN Open Day, April 22, 2017, Neuroinformatics Japan Center demonstrated a Hands-on event, " Find your subjective color by spinning a top". Materials related to the demonstration has been released at Tutorial Content page of this portal. It includes questionnaire, summary on the individual difference of subjective color seeing, how to make a top and a review article on the subjective color. This photo is a wooden benham's Top sold by THE TOYCRAFTER.
Creator of this page: Neuroinformatics Japan Center, RIKEN BSI
Articles: Yoko Yamaguchi; Linked contents Itsuko Ishii, Yoshihiro Okumura, Yoko Morii, Sawako Suenaga, Ayumi Honda, Miyabi Ogawa, Jonathan Lai, Sutthinan Anantarattachai, Munenori Takaku
May 15, 2017
What is Benham's Top?
Benham's Top is a top with a disk of black and white pattern, while it's spinning causes color perception. The color percieved by rotating a black and white pattern is a kind of illusion and is called "subjective color". This phenomena was discovered by a psychologist, Gustaf Theodor Fechner (1801 - 1887), a founder of psychophysics. Benham is a name of the toymaker who made the phenomena popular through the top.
Figure 1 Benham's top movie (left) and the pattern printed on its disk (right). The same pattern is downloadable at Visiome Platform.
If you feel uncomfortable by watching the movie, please stop watching immediately. Please do not watch the movie for a long time near the screen.
Individual difference in subjective color appearance
It is unknown why there is an individual differences in the perception of subjective colors. We conducted a questionnaire on the color perception of Benham's top on RIKEN Open Day, April 22, 2017. We hereby report the questionnaire method and the result summary as below.
Method of questionnaire
Hand-made top was prepared by using a CD disk and a marble. The black and white pattern was printed on the disk. The disk pattern used in the questionnaire consists of four types of stripes, each of which has an interval of 45 degrees as shown in the left picture. The four types of stripes result in perception of four different color bands. These bands are called band 1, band 2, band 3 and band 4 in the order from inside to outside of the disk. The questionnaire sheet uses the Munsell color system. Each participants was asked to select the closest color they perceived on each bands from the Munsell color system. All questionnaires were conducted in Japanese.
The total number of answers was 301. By removing incomplete answers, 280 answers were used for the summary below.
The number of answers of black/white was obviously very few. At each band, one peak or a few peaks with a broad hue distribution were observed. Interestingly, different age groups had diferent hue peaks. Further summary is availble below.(in Japanese only)
Material 1: Summary of questionnaires <PDF>
How to make a top
On RIKEN open day 2016, we cut out a corrugated cardboard into a round shape, and used a toothpick to penetrate through the hole in the center of the circle. The participants enjoyed drawing various kinds of black and white patterns on a paper and placed them on the handmade top. For the RIKEN open day 2017, we have changed the materials of this handmade top from cardboard and toothpick to CD disk and a marble in order to observe the color appearance in more stable rotation. These tops can be made easily. Please download ‘how to make a top ’from below.
Material 2: How to make a top＜PDF＞
Movie of hand-made top
If you feel uncomfortable watching the movie, please stop immediately. Please do not watch the movie for a long time.
Mechanisms of seeing subjective color
Review of mechanism of subjective color in English is to be added soon.
Material 3: Mechanism of seeing subjectibe color (in Japanese only) <PDF>
※This page includes real animations. Please do not keep watching them for a long time.
Hidehiko Komatsu Color- selective neurons Brain Science Dictionary DOI：10.14931/bsd.6413 （2015）
Visiome Platform URL https://visiome.neuroinf.jp/
How to cite
The citation of this page and the linked video/materials are as follows.
Movies and Materials ) Please quote in the order of the creator's name, item type, publisher, and the year.
Movie 1: a movie of Benham's top)
Movie 2: a movie of a handmade top)
Material 1: the summary of questionnaire results)
Material 2: How to make a top)
Material 3: Mechanism of seeing subjective color)