Running head: EARLY MEMORIES
1
Language and Early Memories
by
Jessica L. MacDonald
201004510
A laboratory report
presented to Jenna Wright
in Psychology 260
Developmental
Department of Psychology
St. Francis Xavier University
March 26, 2014
EARLY MEMORIES
2
Introduction
When asked to recall memories from our early childhood, the details are often quite
blurry. Although some individuals are able to easily access these memories, others have a
difficult time retrieving memories from their early life. Most adults are unable to remember
details and events that happened to them before ages 5-7, a phenomenon referred to as
“childhood amnesia” (Morrison & Conway, 2010). Most adults have no memories at all from 0-2
years of age (Hayne, 2004 as cited in Morrison & Conway, 2010) and tend to report their earliest
memory to be at the age of 3-4 years (MacDonald, 2000 as cited in Morrison & Conway, 2010).
The type of memories focused on in these statistics are “episodic memories”, memories of an
individual’s own life and experiences. Episodic memory differs from semantic memory, which is
memory for facts, skills and concepts (Boyd & Bee, 2013).
What is it about the memories of our early childhood that make them so difficult to
reflect on? A process known as encoding helps to explain this. “Encoding” refers to the process
of storing a memory long-term so that it can be recalled at a later date (Wright, 2014). Retrieval
is known as the process in recalling information that has been encoded. The importance of the
event and emotional intensity related to the event often plays an important role in retrieving a
memory. Language ability, understanding of time, sense of self and discussion with others are all
important skills that allow us to have retrievable episodic memories (Wright, 2014). Brain
maturity is also key in the development of memory, particularly in regions of the frontal cortex
and hippocampus (Wright, 2014).
Morrison & Conway conducted a study in 2010 that investigated the link between
childhood amnesia and language development. They believed that the developing child must be
able to understand words related to their experience before they can encode that experience in a
EARLY MEMORIES
way that makes the memory retrievable later on. In other words, we are unable to retrieve
memories from early childhood that were encoded prior to learning the concepts associated with
those memories (Morrison & Conway, 2010). From this general theory, Morrison & Conway
proposed the “retrievability hypothesis” which suggested that individuals are able to form
memories at a young age; yet simply are unable to retrieve them until our language has
developed.
In order to investigate this hypothesis, Morrison & Conway looked at two variables: age
of acquisition (AoA) and age at encoding (AaE). Age of acquisition (AoA) refers to the age at
which a vocabulary word is learned or acquired. Age at encoding (AaE) refers to the age at
which a memory is encoded/when the event occurred. If this retrievability hypothesis was
correct, Morrison & Conway expected to see a relationship between the age of acquisition (AoA)
of words, and the age at encoding (AaE) associated with these words.
Morrison & Conway tested their hypothesis by presenting participants with fifty words
and asking them to recall their earliest memory associated with that word. This task was done
individually, and they were given a week to complete the questionnaire. Words chosen were
normally distributed on a set of measurements based on age of acquisition (AoA), frequency,
image-ability and familiarity (Morrison & Conway, 2010). Participants were asked to recall their
first memory associated with each word, estimate how old they were at the time of the memory
and how confident they were that the age recorded was accurate. Participants were also asked to
provide a brief description of the memory, and a confidence rating that the memory was
accurate. From this experiment, Morrison & Conway found that AoA (age of acquisition) scores
were on average 12 months earlier than AaE (age at encoding) suggesting that the age that words
are acquired is significantly earlier than the age of earliest memories associated with that word.
3
EARLY MEMORIES
4
This supported the retrievability hypothesis proposed by Morrison & Conway, stating that AoA
and AaE are associated, with a strong positive correlation between the two variables.
The present study will further investigate the relationship between language development
and childhood amnesia, based on the research of Morrison & Conway, 2010. It will be a
simplified replication of the study, to investigate the link between the age of acquisition (AoA)
of a word and the age at encoding (AaE) of the memories reportedly associated with that word.
AoA (age of acquisition) and AaE (age at encoding) will remain as the two main variables being
studied, and confidence ratings will be used to determine accuracy of age and memories
recorded. Participants will be given a slightly modified version of the questionnaire used in the
Morrison & Conway (2010) study. The questionnaire will require participants to describe their
earliest memories associated with a list of given words and the age at which those memories
occurred.
From this study, we expect to find a positive correlation between the age of acquisition
and age at encoding, as found by Morrison & Conway in their 2010 study. The age of acquisition
(AoA) is expected to be significantly earlier than the age at encoding (AaE) which will allow us
to make implications on the connection between language development and childhood amnesia.
Methods
Participants
Participants in the present study were Psychology 260 students at Saint Francis Xavier
University. There were 156 participants in total, both male and female. Participants were
required to participate in the study for course credit in the lab component of their developmental
psychology class.
EARLY MEMORIES
Materials
A modified version of the data collection questionnaire used in the Morrison & Conway
(2010) study was used. Participants were asked to provide a description of their earliest memory
associated with a given list of words. Participants were also asked to provide an age at which the
memory occurred, as well as a confidence rating on how confident they were that the age and
memory recorded was accurate. Age at the time of memory was indicated by intervals of 2 years,
ranging from 0-2 years to 9-10 years of age. Confidence measurements were recorded on a 5point Likert-type scale. A rating of 1 indicated the participant was “not at all confident” that their
age or memory was accurate. A rating of 5 indicated extreme confidence. Participants had one
week to complete this task.
Four words from the original Morrison & Conway (2010) word list were omitted due to
unfamiliarity, leaving a set of 46 words. The word “lorry’ was omitted, and the word “ladybird’
was changed to ‘ladybug’. Each word had an age of acquisition (AoA) associated with it to later
be compared with the results of the collected data.
Procedure
Participants were given a questionnaire to complete within the next week and return to
the experimenter. The instructions of the questionnaire were as followed: “We would like you to
recall the first memory you have for each of a list of named objects, so we need you to dig deep
into your memory and think about the first memory you have that is associated with each of the
listed objects. We would like you to estimate how old you were at the time of each event in
memory, and rate how confident you are that the memory and your estimate of your age at the
time is accurate.” (Wright, 2014) The instructions for the questionnaire were consistent with the
instructions used in the Morrison & Conway (2010) study. Prior to data collection, participants
5
EARLY MEMORIES
6
were told their submitted data would be anonymous. Descriptions of memories would not be
linked to a participant’s name, however the confidence ratings and age associated with each
word would be available to research students for data analysis.
Results
There was a positive correlation between AoA and AaE, r(44)= .500, p (<) .001. A
paired samples t-test showed a significant difference between AoA (M=52.76) and AaE
(M=69.80), t(45)= -9.49, p (<).001. The mean difference between AoA and AaE was 17.04
months.
Discussion
The results of the present study supported the hypothesis showing there was a positive
correlation between the age of acquisition (AoA) and the age at encoding (AaE). A paired
samples t-test was performed and showed a significant difference between AoA and AaE, with a
mean difference of 17.04 months. These results suggest that the age at which words are acquired
is consistently earlier than the age at which words are encoded. In other words, the age of the
earliest memories retrievable associated with those words.
The findings of the present study were fairly consistent with the results of the Morrison &
Conway (2010) study. The results suggest that there is, in fact, a systematic lag between age of
acquisition (AoA) and age at encoding (AaE), in the sense that we must first learn a word, before
we are able to encode memories associated with that word. For this study, the systematic lag was
5 months longer than the amount of time found between AoA and AaE in the Morrison &
Conway (2010) study. The correlation found between AoA and AaE in Morrison & Conway’s
EARLY MEMORIES
study was 0.801. Our correlation value was slightly lower, at 0.500 but still remained statistically
significant.
This information allows us to infer that language is an important part of encoding
episodic memories, and that it is necessary to be able to label an experience with language before
we can encode that memory so it can be retrieved in adulthood. Not all memories from childhood
are encoded; a lot of memories tend to be filtered out. It is factors such as attention paid to the
event, personal importance of the event and emotional intensity associated with the event that
make the process of encoding easier, and increase the likelihood of retrieval later in life (Wright,
2014). Sometimes we are exposed to “retrieval cues” that allow us to recall the event more
readily. For this experiment, the words acted as “retrieval cues” however often times, a familiar
smell or sound may trigger the recall of an event from childhood.
One limitation within this study is that all participants were undergraduate students.
Although these students may be from diverse areas across the country, many fall into the same
age category. In other words, all participants recalling childhood memories experienced these
memories approximately 10-15 years ago. What if this study was to be done with a group of
middle-aged adults? Would the same results be found? Would it be more difficult to recall
memories from childhood for older adults than young adults? A second study performed by
Morrison & Conway in 2010 investigated the differences in memory retrieval between two
different age groups. For this study, they changed the word list used so that the words were
associated with events, places, positive emotions or negative emotions. Results of this study
showed the AoA to be significantly earlier than AaE for both age groups, which was consistent
with previous research.
7
EARLY MEMORIES
If we were to take our study further, it would be interesting to replicate this Morrison &
Conway (2010) study (experiment 2) without changing the word list and keeping the word list
consistent with our original study. In this way, we would be able to look at differences in AaE
between two different age groups rather than just looking for a positive correlation between AoA
and AaE. This new information would provide us with more insight of the period of childhood
amnesia and whether we experience a longer period of childhood amnesia as we enter into
adulthood.
8
EARLY MEMORIES
9
References
Morrison, C. M. & Conway, M. A. (2010). First words and first memories. Cognition,
116, 23-32.
Wright, J. (2014). Introduction – lecture notes [PowerPoint slides]. Retrieved from
http://moodle.stfx.ca/course/view.php?id=4295