This experiment was a study of the mental imagery and the experience of spaces during the process of interior design. The experiment was not only used to study the potential of mental imagery in interior design in the absence of other media, i.e., sketching, but it also made a comparative analysis of the imagery during architectural design. The experiment is a continuum of the experiments conducted on designers. This experiment was carried out to study interior designers or architects when designing interiors to ascertain the role of mental imagery, which is different in approach and detailing as compared to the architectural design process. This was achieved by using an experienced architect and blindfolding him during the act of design. The conclusions reached indicate that the designer was able to use imagery very effectively during the act of design.