Serial position effect is the tendency of a person to recall the first and last
items in a series best, and the middle items worst. The term was coined by
Hermann Ebbinghaus through studies he performed on himself, and refers to the
finding that recall accuracy varies as a function of an item's position within a
study list. When asked to recall a list of items in any order, people tend to
begin recall with the end of the list, recalling those items best. Among
earlier list items, the first few items are recalled more frequently than the
middle items. One suggested reason for the primacy
effect is that the initial items presented are most effectively stored in
long-term memory because of the greater amount of processing devoted to them.
The primacy effect is reduced when items are presented quickly and is enhanced
when presented slowly. Longer presentation lists have been found to
reduce the primacy effect. One theorized reason for the recency
effect is that these items are still present in working memory when recall is
solicited. Items that benefit from neither are recalled most poorly. An
additional explanation for the recency effect is related to temporal context:
if tested immediately after rehearsal, the current temporal context can serve
as a retrieval cue, which would predict more recent items to have a higher
likelihood of recall than items that were studied in a different temporal
context. The recency effect is reduced when an interfering task is given.
Intervening tasks involve working memory, as the distractor activity, if
exceeding 15 to 30 seconds in duration, can cancel out the recency effect.
Additionally, if recall comes immediately after test, the recency
effect is consistent regardless of the length of the studied list, or
presentation rate. Amnesiacs with poor ability to form
permanent long-term memories do not show a primacy effect, but do show a recency
effect if recall comes immediately after study. People with Alzheimer's Disease
exhibit a reduced primacy effect but do not produce a recency effect in recall.
Primacy effect The primacy effect, in psychology and
sociology, is a cognitive bias that results in a subject recalling primary
information presented better than information presented later on. For
example, a subject who reads a sufficiently long list of words is more
likely to remember words toward the beginning than words in the middle.
Many researchers tried to explain this phenomenon through free recall tests. In
some experiments in the late 20th century, it was noted that participants
who knew that they were going to be tested on a list presented to them would
rehearse items. Meaning, as items were presented, the participants would repeat
those items to themselves and as new items were presented, the participants
would continue to rehearse previous items along with the newer items. It was
demonstrated that the primacy effect had a greater influence on recall when there
was more time between presentation of items so that participants would have a
greater chance to rehearse previous items.
Overt-Rehearsal was a technique that was meant to test participants' rehearsal
patterns. In an experiment using this technique, participants were asked to
recite out loud the items that come to mind. In this way, the experimenter was
able to see that participants would repeat earlier items more than items in
the middle of the list, thus rehearsing them more frequently and having a better
recall of the prime items than the middle items later on.
In another experiment, by Brodie and Murdock, the recency effect was found to
be partially responsible for the primacy effect. In their experiment, they also
used the overt-rehearsal technique and found that in addition to rehearsing
earlier items more than later items, participants were rehearsing earlier
items later on in the list. In this way, earlier items were closer to the test
period by way of rehearsal and could be partially explained by the recency
effect. In 2013, a study showed that primacy
effect is also prominent in decision making based on experience in a repeated
choice paradigm, a learning process also known as operant conditioning. The
authors showed that there is a large importance to the value of the first
reward on subsequent behaviour, a phenomenon they denoted as outcome
primacy. In another study, the subjects received
one of two sentences. For example, one may be given "Steve is smart, diligent,
critical, impulsive, and jealous." and the other "Steve is jealous, impulsive,
critical, diligent, and smart." These two sentences contain the same
information. The first one suggests positive trait at the beginning while
the second one has negative traits. Researchers found that the subjects
evaluated Steve more positive when given the first sentence, compared to the
second one. Recency effect
Two traditional classes of theories explain the recency effect.
= Dual-store models = These models postulate that later study
list items are retrieved from a highly accessible short-term buffer, i.e. the
short-term store in human memory. This allows items that are recently studied
to have an advantage over those that were studied earlier, as earlier study
items have to be retrieved with greater effort from one’s long-term memory
store. An important prediction of such models
is that the presentation of a distractor, for example solving
arithmetic problems for 10–30 seconds, during the retention period attenuates
the recency effect. Since the STS has limited capacity, the distractor
displaces later study list items from the STS so that at test, these items can
only be retrieved from the LTS, and have lost their earlier advantage of being
more easily retrieved from the short-term buffer. As such, dual-store
models successfully account for both the recency effect in immediate recall
tasks, and the attenuation of such an effect in the delayed free recall task.
A major problem with this model, however, is that it cannot predict the
long-term recency effect observed in delayed recall, when a distractor
intervenes between each study item during the interstimulus interval. Since
the distractor is still present after the last study item, it should displace
the study item from STS such that the recency effect is attenuated. The
existence of this long-term recency effect thus raises the possibility that
immediate and long-term recency effects share a common mechanism.
= Single-store models = According to single-store theories, a
single mechanism is responsible for serial position effects.
A first type of model is based on relative temporal distinctiveness, in
which the time lag between test and the study of each list item determines the
relative competitiveness of an item’s memory trace at retrieval. In this
model, end-of-list items are thought to be more distinct, and hence more easily
retrieved. Another type of model is based on
contextual variability, which postulates that retrieval of items from memory is
cued not only based on one’s mental representation of the study item itself,
but also of the study context. Since context varies and increasingly changes
with time, on an immediate free-recall test, when memory items compete for
retrieval, more recently studied items will have more similar encoding contexts
to the test context, and are more likely to be recalled.
Outside immediate free recall, these models can also predict the presence or
absence of the recency effect in delayed free recall and continual-distractor
free-recall conditions. Under delayed recall conditions, the state of test
context would have drifted away with an increasing retention interval, leading
to an attenuated recency effect. Under continual distractor recall conditions,
while the increased interpresentation intervals reduces the similarities
between the given study contexts and test context, the relative similarities
amongst items remains unchanged. As long as the recall process is competitive,
recent items will win out, so a recency effect is observed.
= Ratio Rule = Overall, an important empirical
observation regarding the recency effect is that it is not the absolute duration
of retention intervals or of inter-presentation intervals that
matters. Rather, the amount of recency is determined by the ratio of RI to IPI.
As a result, as long as this ratio is fixed, recency will be observed
regardless of the absolute values of intervals, so that recency can be
observed at all time scales, a phenomenon known as time scale
invariance. This contradicts dual-store models, which assume that recency
depends on the size of STS, and the rule governing the displacement of items in
the STS. Potential explanations either then
explain the recency effect as occurring through a single, same mechanism, or
re-explain it through a different type of model that postulates two different
mechanisms for immediate and long-term recency effects. One such explanation is
provided by Davelaar et al., who argue that there are dissociations between
immediate and long-term recency phenomena that cannot be explained by a
single-component memory model, and who argues for the existence of a STS that
explains immediate recency, and a second mechanism based on contextual drift that
explains long-term recency. Related effects
In 1977, William Crano decided to outline a study to further the previous
conclusions on the nature of order effects, in particular those of primacy
vs. recency, which were said to be unambiguous and opposed in their
predictions. The specifics tested by Crano were:
Change of meaning hypothesis "adjectives presented first on a
stimulus list established a set, or expectation, through which the meanings
of the later descriptors were modified in an attempt to maintain consistency in
the mind of the receiver." Inconsistency discounting
"later descriptions on the stimulus list were discounted if inconsistent with
earlier trait adjectives." Attention decrement hypothesis
"earlier adjectives would wield considerably more influence than the
later ones, and a primacy effect in the typical impression formation task would
be expected to occur ... even when the stimulus list contains traits of a high
degree of consistency." The continuity effect or lag-recency
effect predicts that having made a successful recall, the next recall is
likely to be a neighboring item in serial position during the study period.
The difference between the two items' serial position is referred to as serial
position lag. Another factor, called the conditional-response probability,
represents the likelihood that a recall of a certain serial position lag was
made. A graph of serial position lag versus conditional response probability
reveals that the next item recalled minimizes absolute lag, with a higher
likelihood for the adjacent item rather than the previous one.
See also Clive Wearing
Free recall Henry Molaison
Law of primacy in persuasion Learning curve
List of memory biases List of cognitive biases
Outcome primacy Principles of learning
Peak-end rule Reminiscence bump
Notes References
Frensch, P.A.. Composition during serial learning: a serial position effect.
Journal of Experimental Psychology: Learning, Memory, and Cognition, 20(2),
423–443. Healy, A.F., Havas, D.A., & Parkour,
J.T.. Comparing serial position effects in semantic and episodic memory using
reconstruction of order tasks. Journal of Memory and Language, 42, 147–167.
Glanzer, M. & Cunitz, A. R.. Two storage mechanisms in Free Recall. Journal of
Verbal Learning and Verbal Behaviour,5,351–360.
Kahana, M. J., Howard, M. W., & Polyn, S. M.(2008). Associative Retrieval
Processes in Episodic Memory. Psychology.
Paper 3. Howard, M. W. & Kahana, M.. Contextual
Variability and Serial Position Effects in Free Recall. Journal of Experimental
Psychology: Learning, Memory & Cognition, 25(4), 923–941.
Further reading Luchins, Abraham S. Primacy-recency in
impression formation Liebermann, David A. Learning and
memory: An integrative approach. Belmont, CA: Thomson/Wadsworth, 2004,
ISBN 978-0-534-61974-9.