1. A method of operating an electronic device, the method comprising: displaying a first image; detecting a plurality of positions designated by an input device during a plurality of frames; calculating an average position by averaging the positions; identifying a user-interested region from a region including the first image based on the average position; and displaying a bioeffect image at the user-interested region, wherein the first image and the bioeffect image are different images, and wherein the bioeffect image is a type which is to induce at least one of a therapeutic effect or a predetermined physiological response of a person.