Foundations Of Cognitive Science

Intrusion Errors

In a recall portion of a memory task, these are errors that occur when the subject includes items that were not on the original list. For instance, consider situations in which the conditions of a free recall task are such that the primacy effect is reduced (Glanzer & Cunitz, 1966), indicating poorer recall from secondary memory. Intrusion errors are often the source of this decrease -- subjects respond with a synonym of a presented word, which is scored as an error. Intrusion errors can also be used to explain subjects' tendency to recognize sentences whose semantics parallel presented material, but which were not actually presented (Bransford, Barclay & Franks, 1972). In short, intrusion errors often reflect constructive, semantic processes in memory.


  1. Bransford, J. D., Barclay, J. R., & Franks, J. J. (1972). Sentence Memory - Constructive versus interpretive approach. Cognitive Psychology, 3(2), 193-209.
  2. Glanzer, M., & Cunitz, A. R. (1966). Two storage mechanisms in free recall. Journal of Verbal Learning and Verbal Behavior, 5(4), 351-360.

(Revised March 2010)