This paper analyses the impact of search engines on our cognitive and epistemic practices. For that purpose, it describes the processes of assessment of documents on the Web as relying on distributed cognition. Search engines together with Web users, are distributed assessment systems whose task is to enable efficient allocation of cognitive resources of those who use search engines. Specifying the cognitive function of search engines within these distributed assessment systems allows interpreting anew the changes that have been caused by search engine technologies. The paper describes search engines as implementing reputation systems and points out the similarities with other reputation systems. It thus calls attention to the continuity in the distributed cognitive processes that determine the allocation of cognitive resources for information gathering from others.