Successful list-method directed forgetting without retroactive interference of post-instruction learning.

The focus of the study is the role of interference in list-method directed forgetting. More specifically, our question was whether retroactive interference of the to-be-remembered information is a necessary prerequisite for the directed forgetting effect. In Experiment 1 we used a directed forgetting procedure with one learning list without the interference of any to-be-remembered information. In line with previous results, we did not find a significant directed forgetting effect. Experiment 2 applied a directed forgetting procedure with two study lists, however, the forget instruction was given following the second list. So, List 2 items were designated as to-be-forgotten items, without further learning, whereas List 1 items were to-be-remembered items. The forget instruction selectively decreased the recall of List 2 items, without decreasing the recall performance for List 1. In Experiment 3, using the same procedure with different items, smaller learning lists and reversed output order, we replicated the results of Experiment 2. Altogether, these results point to a flexible, goal-related nature of the directed forgetting phenomenon, showing that some form of interference is a necessary requirement for successful directed forgetting. However, proactive interference of to-be-remembered information in interaction with a forget instruction is suitable for forgetting of subsequently encoded information.