1. An information displaying apparatus comprising: a displaying unit configured to display first content on a display; an audience state detecting unit configured to detect an audience state representing a physical state of an audience member positioned in front of the display; an interest degree estimating unit configured to estimate an interest degree based on the audience state detected by said audience state detecting unit, the interest degree indicating a degree of interest of the audience member in the first content displayed on the display by said displaying unit; and a display control unit configured to cause said displaying unit to is display second content with a clarity degree or an exposure degree of at least a part of the second content reduced below a predetermined clarity degree or a predetermined exposure degree when magnitude of a change rate of the interest degree estimated by said interest degree estimating unit is smaller than a first threshold.