Proactive interference refers to the interfering effect of previously lean materials on the learning of new materials. The prefix ‘pro’ means ‘forward acting.’ The old memory acts in a forward direction to interfere with the memory.
The phenomenon of proactive interference can be demonstrated the laboratory by taking an experimental group and a controlled group. The experimental group learns a list of nonsense syllables (List A), while the control group takes rest. Then both the groups learn List B. The next step is to a; both groups to recall List B. It is generally found that the experimental group recalls less number of nonsense syllables of List B, compared to the control group.
Thus, the initial learning of List A by the experimental group works (forward in interfering with the recall of List B. The control group did not experience the interference of List A, and therefore, performed better in the recall test of List B.