Information gathering from sources outside the company plays a critical role in most innovation projects. Particularly, it seems promising to approach external market experts to develop an indepth understanding of current use problems, changing customer needs and trends for new product solutions. When planning expert interviews, firms are confronted with the question whether knowledge is distributed rather homogeneously or heterogeneously ("scattered") among a pool of experts. This issue strongly determines how many experts need to be interviewed in order to develop a comprehensive understanding of a given search field for innovation. In the present paper we analyse expert interviews that were conducted in the context of an innovation project in the field of surgical hygiene products. We find high heterogeneity of expert knowledge: Market experts in our sample vary in terms of market information they provide for the particular product field. We argue that this finding is in alignment with the concept of "bounded rationality" and the theory of "contextual development of knowledge". Our findings have implications for the management of external information gathering and the identification of market experts.