The serial position effect is a tendency to recall with greater accuracy the items that fall at the beginning and end of a list, as opposed to the items in the middle. This can play an important role in knowledge acquisition and can also be a factor when performing tests to assess cognitive function. Studies on this effect may be useful for activities like the development of effective advertising materials, where the advertiser wants the target to take key information away after exposure to an ad.
Several different factors play a role in the serial position effect. One is primacy, where people have a better memory for information at the beginning of a list. At the other end, recency can play a role in how people remember lists, as the last few items will stick in their heads. Primacy tends to decrease when a subject rehearses all the items on a list an equal number of times, and recency is less common when time passes between hearing the list and the time he is asked to repeat it.
In the serial position effect, the subject may be more inclined to remember the start of the list because of primacy and the very end because of recency. Accuracy for items in the middle is more dubious, as the subject may have trouble storing and retrieving these memories. On something like a cognitive function test, caregivers have to consider this effect. To address recency, for example, the caregiver might give a patient a list to remember and check in two weeks later to see which items the client can recall.
In free recall, the items at the start and end of the list may surface first because of the serial position effect. One way to make sure a subject learns everything on the list is to mix up the order, or to ask the subject to rehearse all the items a set number of times. Consideration of the effect can also play a role in the presentation of information; for example, a seven-digit phone number may be easier to remember than one with ten digits, and thus it may be more common to exchange short numbers without an area code.
Other factors can influence the serial position effect. Distracting elements may make it harder to store and recall memories. If the list is presented in different voices or fonts, for example, the subject may have more difficulty with it. Likewise, environmental distractions like loud noises or strong odors can skew the subject's memory.