Several techniques in artificial intelligence have shown a great potential to develop useful human-computer interfaces, but it is still quite far from realizing a system of matching the human performance, especially in terms of emotion, intuition and inspiration. To overcome this shortcoming, we present a promising technique called interactive genetic algorithm (IGA), which performs optimization with human evaluation, and with which the user can obtain what he has in mind through repeated interaction. To project the usefulness of the IGA to develop emotional human-computer interfaces, we have applied it to the problems of image and music information retrieval. Several experiments show that our approach allows us to design and search digital media not only explicitly expressed, but also abstract images such as "cheerful impression," and "gloomy impression." It is expected that the same approach can be applied to many other problems in musical information retrieval and manipulation based on intuition and inspiration.