Further Factors Affecting Serial Recall
It was stated earlier that control state models handle the fact that an omitted item does not break the chain of activation that provides recall across a series of target items. This introduces the question of why some items fail to be recalled. The present approach posits that activity continues steadily through the sequence of control nodes or control states, providing input to each item in order. Clearly, however, this input is not sufficient to activate all the items to the threshold of recall (under typical testing conditions). The assumption here is that each item has its own background level of activity, which combines with input from the control states to determine whether the item will be retrieved. A wide range of factors can influence the level of background activity of a word or letter or number target. Degree of rehearsal is obviously one of them. Degree of attention could be another. Some properties of words (e.g. high imagery potential) also make them easier to retain; yet another factor (to be examined later) involves background associations with other material. And interference effects provide a major source of impairment in the capacity to recall an item, and also to recall an item in its correct position.