Serial memory processing is the act of attending to and processing one item at a time. This is usually contrasted against parallel memory processing, which is the act of attending to and processing all items simultaneously. In short-term memory tasks, participants are given a set of items (e.g. letters, digits) one at a time and then, after varying periods of delay, are asked for recall of the items. Participants could also be asked whether a specific target item was present in their original set. The serial order of items and the relationships between them can have varying affects on the item's speed and accuracy of recall.