Resumen
According to our study, based on interviews with households in a residential area in Sweden, uncertainty is a cultural barrier to improved recycling. Four causes of uncertainty are identified. Firstly, professional categories not matching cultural categories?people easily discriminate between certain categories (e.g., materials such as plastic and paper) but not between others (e.g., packaging and ?non-packaging?). Thus a frequent cause of uncertainty is that the basic categories of the waste recycling system do not coincide with the basic categories used in everyday life. Challenged habits?source separation in everyday life is habitual, but when a habit is challenged, by a particular element or feature of the waste system, uncertainty can arise. Lacking fractions?some kinds of items cannot be left for recycling and this makes waste collection incomplete from the user?s point of view and in turn lowers the credibility of the system. Missing or contradictory rules of thumb?the above causes seem to be particularly relevant if no motivating principle or rule of thumb (within the context of use) is successfully conveyed to the user. This paper discusses how reducing uncertainty can improve recycling.