Control method for display device and display device

A display device comprising:

• a display section configured to display a first image on a first display surface;
• a specifying section configured to specify a number of first people viewing the first image displayed on the first display surface;
• a communication section configured to receive, from another display device that displays a second image different from the first image on a second display surface different from the first display surface, number-of-people information indicating a specifying result of a number of second people viewing the second image displayed on the second display surface;
• a comparing section configured to compare the number of the first people and the number of the second people;
• and
• a control section configured to control the display section to display the second image on the first surface when the number of the first people is smaller than the number of the second people, while keeping the second image displayed on the second display surface;
• and control the communication section to transmit, to the other display device, first image instruction information for instructing display of the first image on the second display surface when the number of the first people is larger than the number of the second people, while keeping the first image displayed on the first display surface.