Entrenchment: effects of multiple red herrings on memory blocks in word fragment completion

Two experiments examined blocking and entrenchment using a word fragment completion task. After incidental priming tasks in which varying numbers of red herring stimuli (i.e., wrong answers to subsequent problems) were seen, word fragment completion was tested for items orthographically similar to primed words. Both experiments showed a memory blocking effect, poorer fragment completion when any red herrings had been seen, relative to a control (zero red herrings) condition. An entrenchment effect, poorer performance when more red herrings were primed, was also observed. Both experiments show that entrenchment effects occur with indirect measures of memory, and these results have implications for fixation effects in problem solving.