In the referred experiment, the participants that were placed in the forced response group had the lowest overall accuracy; they had no motivation to provide accurate responses and were forced to respond even when they were unsure of the answer. Another study done by Hill RD, Storandt M, and Simeone C tested the impact of memory skills training and external reward on free recall of serial word lists. Effects similar to those reported in the previous study were seen in children—in contrast to older learners. In the absence of interference, there are two factors at play when recalling a list of items: the recency and the primacy effects. The recency effect occurs when the short-term memory is used to remember the most recent items, and the primacy effect occurs when the long-term memory has encoded the earlier items. The recency effect can be eliminated if there is a period of interference between the input and the output of information extending longer than the holding time of short-term memory (15–30 seconds). This occurs when a person is given subsequent information to recall preceding the recall of the initial information. The primacy effect, however, is not affected by the interference of recall. The elimination of the last few items from memory is due to the displacement of these items from short term memory, by the distracting task. As they have not been recited and rehearsed, they are not moved into long-term memory and are thus lost. A task as simple as counting backwards can change memory recall; however an empty delay interval has no effect. This is because the person can continue to rehearse the items in their working memory to be remembered without interference. Cohen (1989) found that there is better recall for an action in the presence of interference if that action is physically performed during the encoding phase. It has also been found that recalling some items can interfere and inhibit the recall of other items. Another stream of thought and evidence suggests that the effects of interference on recency and primacy are relative, determined by the ratio rule (retention interval to inter item presentation distractor rate) and they exhibit time-scale invariance. Context-dependency effects on recall are typically interpreted as evidence that the characteristics of the environment are encoded as part of the memory trace and can be used to enhance retrieval of the other information in the trace. In other words, you can recall more when the environments are similar in both the learning and recall phases. Context cues appear to be important in the retrieval of newly learned meaningful information. In a classic study by Godden and Baddelley (1975), they demonstrated that deep-sea divers recalled their training more effectively when trained underwater, rather than being trained on land.