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Abstract
Episodic memory is the process of recalling personally experienced past events.
The efficiency of this process is adversely affected by age. In a sense, this
may explain the level of emotional distress that the aged and their kin and all
others feel at the onset of failing episodic memory. Because it relates to
individuals and their family and friends in a very personal way, it tends to
rob them of past-shared experiences in a way that other memory failures do not.
Introduction
The mechanism of human memory recall is neither a parallel nor a sequential
retrieval of previously learned events. Instead, it is a complex system that
has elements of both sequential and parallel modalities, engaging all of the
sensory faculties of the individual. On an everyday level, issues about memory
and recall affect everyone. It has a bearing on ramifications from the trivial
to matters of life and death. Thus, a particular student might worry about his
or her ability to remember \'memorized\' material, a person might worry about
losing his or her mind, and, there are the more troubling issue of diseases
affecting memory such as Alzheimer\'s disease. According to Tulving, episodic
memory represents only a small part of the much larger domain of memory
(Tulving, 1992, p.1). Specifically, episodic memory is the process involved in
remembering past events. This paper is a review of research findings on
episodic memory with specific attention to episodic memory in adults and
infants.
Episodic Memory in Adults
In society, it is quite common for people in their golden years or even well
before that, to worry about losing their memory. There is scientific evidence
to support this notion of degradation of memory with age. It is now well known
in neurology that brain cells die off as one ages. Verhaeghen and Marcoen
(1993, pp. 172-178) found that the decline associated with age in relation to
the ability to perform episodic memory tasks involving deliberate recall
appears to be largely a quantitative rather than a qualitative phenomenon. The
ability of older adults to recall individual items in lists, or ideas in texts
could be predicted based on the performance by younger adults on the same
tasks. From their data in a sample of 48 younger and 45 older adults, they
postulated a relationship between recall and age with a median correlation of r
= .88. Younger or older adults could use the same item characteristics to
predict probability of recall.
Kliegl and Lindenberger (1993, pp. 617-637) tested a model for correct recall and
intrusions in cued recall of word lists. Intrusions are defined as false
responses that were correct in an earlier list. The model assumes three
exclusive states for memory traces after encoding; 1) with a list tag-with
information about list origin, 2) without list tags, and 3) missing. Across
lists, a trace can lose its list tag or it\'s content. For retrieval, an
optimal strategy of response selection was assumed. Younger and older
laboratory-trained mnemonists participated in two separate experiments in which
recall of permutations of a single word list across a single set of cued was
held constant with individually adjusted presentation times. They reported that
younger adults were more apt to have correct recall, while older adults were
more susceptible to intrusions. Age differences were restricted to model
parameters estimating the probability of generation of list tags.
In another study, Denney and Lasen (1994, pp. 270-275) compared the ability of
youngsters and adults to remember specific information and / or information
related to a particular context. They investigated the ability of individuals
not just to remember some given information, but also the ability to connect
specific information related to a context. The study involved eighty adults in
a bimodally stratified age range. The subjects were either between 18 and 30
years of age or 60 and 85 years. They were shown slides containing a word
related to specific information. Denney and Lasen concluded that although the
elderly have memory problems, it is not with regard to remembering specific
information. In a study of adults with a similar bimodal age distribution,
(eighteen men, 18- to 26-years-olds and eighteen men, 60- to 79-year-olds),
Jennings, Nebes, and Yovetich (1990, pp. 77-91) hypothesized that older
volunteers allocate more attentional resources to memory maintenance than do
younger volunteers. Allocation of a resource supporting memory maintenance was
inferred from performance and cardiovascular measures. Individuals performed a
serial memory task both as a \'single task\' and as a \'dual task\' that added
simple reaction time stimuli. Jennings et al. found that items presented early
or later in the serial list created relatively low and high memory loads,
respectively. The results of this task-oriented experiment suggested that older
men allocated greater attention to memory maintenance, particularly during
high-memory-load items and activities. The older men exhibited a slowing of
dual-task reaction time and increased heart rate during high- versus
low-memory-load items. Cardiac and vascular reactions further suggested that
memory maintenance is supported by phasic autonomic adjustments, and that with
age; more of this support is required for adequate maintenance of episodic memory.
The foregoing studies were focused on understanding memory in healthy adults.
Since failing memory and mental diseases have been shown to have some
association, some studies have also examined the use of memory in the diagnosis
of primary stages of dementia. Herlitz, Hill, Fratiglioni, and Backman (1995,
pp. M107-M113) reported that a study of the efficiency of cognitive tests in
diagnosing and staging dementia proceeds with the aid of cognitive parameters
evaluating episodic memory, while visuospatial assessments help stage dementia.
This finding was held by the researchers to imply a faster degeneration of
episodic memory than visuospatial capacities.
Episodic Memory in Infants
Bauer and Dow (1994, pp. 403-417) conducted a series of three experiments that
tested whether 1- to 2-year-olds generalize their knowledge of events to new
\"instantiations,\" and postulated one possible mechanism by which
generalization is accomplished. In their first experiment, 16 and 20 month-old
children enacted six separate event sequences. One week later the same children
were tested for delayed recall. At delayed testing, the props used to enact
one-half of the events were replaced by novel, functionally equivalent props.
Children in both age groups used the new props to enact the events, thereby
demonstrating spontaneous generalization. Experiments 2 and 3 tested whether
generalization is accomplished through forgetting of the specific details of
the original event. At Session 1, 16- (Experiments 2 and 3) and 20-month-olds
(Experiment 2) enacted four separate events. One week later the same children
selected from an array of props those used to enact the events in Session 1.
Among the objects from which selection was made were functionally equivalent
props of the sort used to assess generalization in Experiment 1. Children in
both age groups performed reliably on the recognition-memory task. Results
found that 16- and 20-month-old children have at their disposal the capacity to
productively generalize their knowledge of events and to form specific,
episodic event memories.
Reference
Redish, A. David (1999). Beyond the Cognitive Map : From Place Cells to
Episodic Memory
Tulving, E. (1994). Elements of Episodic Memory. Oxford Psychology Series, No
2.
Tulving, E. (1999). Memory, Consciousness, and the Brain: The Tallinn
Conference.
Zimmer, H. D. (2000). Memory for Action : A Distinct Form of Episodic Memory
(Counterpoints (Oxford University Press).