Editing Interference theory (section)

====With lists====
Researchers have studied the joint influence of proactive and retroactive interference using a list of items to be remembered. As expected, the recall was hampered by increasing the number of items in a given list.<ref>{{cite journal|last=Murdock|first=Bennet B.|title=Short-term memory and paired-associate learning|journal=Journal of Verbal Learning and Verbal Behavior|date=1 November 1963|volume=2|issue=4|pages=320–328|doi=10.1016/S0022-5371(63)80100-0}}</ref> Proactive interference also affected learning when dealing with multiple lists. Researchers had participants learn a list of ten paired adjectives.<ref>{{cite journal|last=Greenberg|first=R.|author2=Underwood, B.J.|title=Retention as a function of stage of practice|journal=Journal of Experimental Psychology|date=August 1950|volume=40|issue=4|pages=452–7|pmid=15436941|doi=10.1037/h0062147}}</ref> The experimenters would consider a list to be learned if the participant could correctly recall eight of the ten items. After two days, participants could recall close to 70% of the items. However, those asked to memorize a new list the day after learning the first one had a recall of only 40%. Those who learned a third list recalled 25% of the items. Therefore, proactive interference affected the correct recall of the last list learned, because of the previous one, or two. In terms of forgetting, the effect of proactive interference was supported by further studies using different methods.<ref>{{cite journal|last=Underwood|first=Benton J.|title=Interference and forgetting.|journal=Psychological Review|date=1 January 1957|volume=64|issue=1|pages=49–60|doi=10.1037/h0044616|pmid=13408394}}</ref> The effect of proactive interference was reduced when the test was immediate and when the new target list was different from the previously learned lists.