Many studies have shown that the appearance of products has a great impact on consumers. In addition to functionality, aesthetics is of paramount importance in many branches of product design. Visual appearance includes, among other things, the colour, shape, and pattern of the product. The effect of shapes and colours is often studied, but not much data are available on the emotional impact of patterns. This study specifically examines the impact of geometric patterns, which may be of help in the work of product designers. Interviews and questionnaires based on a newly introduced method revealed, for instance, that the basic geometry that makes up geometric patterns and the way the pattern is arranged fundamentally influence the effect of the pattern on consumers.