Blocking, "...the non-occurrence of one form due to the simple existence of another" [Aronoff, Mark, 1976, “Word formation in generative grammar” (Linguistic Inquiry Monographs; 1), MIT Press, Cambridge MA, p. 43], is a widely observed phenomenon in English morphology, within pairs of competing morphological rules, especially when one rule is located on stratum 1 and the other on stratum 2. In such cases, the attachment of stratum-1 affix to a given base blocks the lternative attachment of the competing stratum-2 affix to that base.
- Giegerich (2004), Pag. 192