Phonological similarity effects in simple and complex word spans

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TABLE OF CONTENTS

Acknowledgement…………………………………………………………………………..6

Abstract ……………………………………………………………………………………..7

Chapter I: Introduction .........................................................................................................8
Working memory theory……………………………………………………………...…….8
Some phenomena found in working memory………………………………………………13
Simple and complex span tasks …………………………………………………………….15
Phonological similarity effect ………………………………………………………....……19
Study by Copeland and Radvansky……………………………………………..…………..22
Context Availability Model……………………………………………………..…………..25
Motivations for the current study…………………………………………………………...32
General Predictions…………………………………………………………..……………..35

Chapter II: Pilot Study …….……………………………………………………..………...36
Method…………………………………………………………………………….…….….37
Participants………………………………………………………….………….…...37
Design….…………………………………………………………..……………….37
Material….………………………………………………………………………….37
Procedures………………………………………………….……………............................39
Scoring………………………………………………………………………………….….41


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Results……………………………………………………………………………..………43
Error Analysis……………………………………………………………………………..46
Discussion………………………………………………………………………..………..49

Chapter III: Experiment I………………………………………………………………….53
Method…………………………………………………………………………………….53
Participants………………………………………………………………………..53
Design...………………………………………………………………….…….. ...53
Material….…………………………………………………………………….…..54
Procedure………………………………………………………………………………….55
Apparatus and Scoring……………………...……………………………………………..57
Results……………………………………………………………………………………..57
Analysis across trials……………………………………………………………………....61
Discussion……………………………………………………………................................64

Chapter IV: Experiment II………………………………………………………………...68
Method…………………………………………………………………………………….69
Participants………………………………………………………………………...69
Design………………………………………………………………………….......70
Material…………………………………………………………………………….70
Procedure…………………………………………………………………………………..74
Scoring…………………………………………………………………………………......75
Results………………………………………………………………………………….......75


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Discussion…………………………………………………………………………………..78

Chapter V: General Discussion……………………………………………………………..81
Summary of results for experiment…………………………………………………………81
Error Patterns……………………………………………………………………………….84
Scoring procedure…………………………………………………………………………..85
Reversal of the phonological similarity effect………………...............................................87
Contextual value of sentences………………………………………………………...…....89

Relevance of the findings for reading span task…………………………………………....90
Working Memory…………………………………………………………………………..90
Limitations of the current study and future directions……………………………………..91
Conclusion…………………………………………………………………………………94

References…………………………………………………………….................................95

Appendixes…………………………………………………………… ………………..….101
Appendix A: Word lists used in Pilot study……………………………………..…101
Appendix B: List of words changed for Experiment I………….……………….....112
Appendix C: Word list used for word span task in Experiment I.............................113
Appendix D: Sentences for reading span task in Experiment I.................................122
Appendix E: Sample questionnaire used for Experiment II...…………...……..…..133
Appendix F: Final questionnaire used for Experiment II..........................................136
Appendix G: High context sentences used in Experiment II……………………….138


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Appendix H: Low context sentences used in Experiment II……………………….143

List of Tables

Table 1: Average means and standard deviations for word lists used in Pilot study………38
Table 2: Means of Absolute span scores of recall for similar and dissimilar conditions in pilot
study…………………………………………………………………………………………44
Table 3: Means of Total span scores of recall for similar and dissimilar conditions in pilot study
………………………………………………………………………………………………45
Table 4: Error analysis Pilot study..……………………………………….........................48
Table 5: Average means and standard deviations for word lists used in Experiment I…...55
Table 6: Means similar and dissimilar conditions in word and reading span tasks……….57

Table 7: Error analysis Experiment I……………………………...………………………60
Table 8: Average means and standard deviations for word lists used in Experiment II….70
Table 9: Serial recall proportion across list type and context conditions...……………….75
Table 10: Error analysis Experiment II…………………………………………………….77


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List of Figures

Figure 1: A simple representation of the working memory model by Baddeley and Hitch.....10
Figure 2: Means similar and dissimilar conditions with Total span scores………………..…44
Figure 3: Means similar and dissimilar conditions with Absolute span scores….……….......46
Figure 4: Means for word and reading span using Absolute span task…………………..…..58
Figure 5: Means for word and reading span using Total span task…………………………..58
Figure 6: Analysis across list lengths for word span…………………………………………62
Figure 7: Analysis across list lengths for reading span………………………………………63
Figure 8: Mean proportion of recall of similar and dissimilar words………………………..76


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Acknowledgement

I would like to thank my supervisor, Dr. Winston Goh for his immense and valuable help and
support. His guidance has helped me achieve a deeper knowledge of the subject.

Also, I would like to extend my sincere gratitude to David Copeland for sending me the samples of
the materials used in his study.

A few other people deserve to be thanked for their assistance in preparing this thesis. My sincere
thanks to the reviewers who provided good feedback which helped me shape this study. Also I
would like to mention my parents who gave me support in every way possible.

Lastly, I would like to extend my sincere gratitude towards National University of Singapore for
giving me an opportunity to put my thoughts and ideas to practice.


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Abstract

Memory span for a list of phonologically similar words is generally worse than memory span for a
list of phonologically dissimilar words, a finding that is called the phonological similarity effect.
This finding has often been cited as evidence for the use of phonological coding in short-term
memory and working memory. However, some studies have demonstrated a reversal of the
phonological similarity effect under certain conditions. One such condition is the use of more
complex memory span tasks such as reading span. It has been suggested that sentence contexts may
provide additional retrieval cues that may overcome the detrimental effects of phonological
similarity. The present study examined this hypothesis by manipulating the sentence contexts of the
reading span materials. A pilot study confirmed the phonological similarity decrement in a word
span task, showing a higher recall for dissimilar sounding words than the similar sounding words.
This was followed by Experiment I which consisted of a word span and a reading span task. The
results showed that unlike the word span task, phonological similarity facilitation effect was
observed in the reading span task. Further extension of the study led to Experiment II which tried to
investigate the effect of context on the recall of the participants on a reading span task employing
high and low context sentences. No evidence showing phonological similarity facilitation was found;
in fact, the standard phonological similarity decrement in memory span performance was observed
with high context sentences.

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Chapter I: Introduction

Working memory theory
The expression ‘working memory’ was initially used by Miller, Galanter and Pibram (1960)
in the book titled ‘Plans and the structure of behavior’. According to the authors, the study of
working memory and its concepts are recognized as a milestone in the early development of
cognitive psychology, and interestingly working memory was assigned a central role to this account.
Working memory collects different information in the mind of the individual at one point of
time and then relates it to other things. It could be defined as a system which is responsible for the
brief storage and management of the information essential for accomplishing complex cognitive
actions like learning a task, reasoning out things, and comprehension of text, etc. (adapted from
MedicineNet.com) This system could thus be understood to be involved in the selection, initiation,
and termination of information-processing functions such as encoding, storing, and retrieving data.
Such a system seems to be very helpful if one is striving to read sentences whose meaning can only
be deciphered after it has been fully read (Baddeley, 1999). Other tasks which require a similar
system are the processes of performing mental mathematics, reasoning out things, and also times
when one is faced with a task of problem solving (Baddeley, 1999).

The roots of working memory can be traced from the theories of short-term memory
(Andrade, 2001; Baddeley & Hitch, 2000) which primarily focused on the storage of information on
a temporary basis. Discussion regarding the role of short term memory has more often concluded the
fact that short term memory functioned as working memory (Andrade, 2001). In contemporary
theories of working memory, the theory of Miller et al., (1960) is not widely mentioned. Traces of


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origin of the concepts of working memory could be found in the studies by Atkinson and Shiffrin
(1968). Their study contained a thorough analysis of views related to the structure and the functions

of human memory. The analysis of their study postulated three main components involved in the
structure. They were a sensory register, a short term store, and a long term store. Atkinson and
Shiffrin were of the view that the short term store could be considered to be ‘working memory’
which receives inputs from the sensory register and the long term store.

Both the original accounts presented by Miller et al. (1960) and that by Atkinson and Shiffrin
(1971) demonstrated what Baddeley (1986) later defined as the ‘general concept of working
memory’. Baddeley and Hitch (1974) identified three main components of working memory as
depicted in Figure I
•

A central executive

•

Articulatory loop (also known as phonological loop) holding information in the phonological
form.

•

A visuo-spatial scratch pad (now also known as visuo-spatial sketchpad) specialized for
spatial and visual coding.


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VISUO –
SPATIAL
SKETCH PAD

CENTRAL
EXECUTIVE

PHONOLOGICAL
LOOP

Figure1: A simple representation of the Working Memory Model by Baddeley and Hitch. Adapted
from Baddeley (1999).

The central executive component is the most important one and its functions included regulation
of information within working memory, and retrieving of information from other systems like
long term memory and the processing and storage of information. The cognitive tasks that
appear to involve the central executive include mental arithmetic, recall of digits, logical
reasoning, semantic verification and recollection of events from long term memory.

There have been a number of advances in understanding the central executive component of
working memory (Baddeley & Logie, 1999). Much of the current work on the regulatory functions
of the central executive is guided by a model developed by Shallice (1982, see also Norman &
Shallice, 1986). In their model action is controlled by two ways. Well learned or automatic activities


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are guided by schemas that are generated by environmental cues. According to their study, the
supervisory attention system is a limited capacity system and is used for a variety of purposes,
including tasks involving planning or decision making, trouble shooting in situations in which the
automatic processes appear to be running into difficulty, novel situations, dangerous or technically
difficult situations, situations where strong habitual responses or temptations are involved.

The central executive is supplemented by two components which can also be identified as the
‘slave systems’. Each slave system is specialized for the temporary maintenance and the processing

of the material within a particular area. One of the two slaves is the phonological loop which is
responsible for maintaining verbally coded information. The phonological loop comprises two
components, the phonological store and the articulatory loop. The phonological store includes the
material in a phonological code and these codes decay as time passes (Baddeley & Gathercole,
1993). A process of rehearsal using the articulatory loop helps refresh the decaying representations
in the phonological store and also maintains memory items.

Concerning the functions of the phonological loop it is stated that it may be held responsible
for the temporary storage of verbal information, particularly novel phonological input (Baddeley,
Gathercole, & Papagno, 1998). Yet another important function which it performs is that the
temporary storage of the material allows the listener to create long-term phonological representations
of that material (Baddeley et al., 1998).

The other slave, the visuo-spatial sketchpad, is concerned with the short term processing and
maintenance of material which has a strong visual or spatial component. Such material is then


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encoded in the form of imagery. Baddeley (1986) hypothesized that the visuo-spatial sketchpad is
able to serve imagery as well as short term memory functions, arguing that there seems to be some
evidence available to prove the occurrence of a visuo-spatial store (pg 143). This slave system
specializes in the processing and storage of visual and spatial information. It is also capable of
processing and storing verbal information in the form of images (Baddeley & Gathercole, 1993).
Storage and processing of information are the two distinct aspects of working memory. The central
executive is mainly responsible for the processing, control and integration of information whereas
the storage component is taken care of by the slave systems, although some simple processing
mechanisms such as rehearsal in the articulatory loop are placed in the slave systems. In terms of
theoretical progress related to the functions and structure of the two slave systems, the phonological
loop has made more progress than the visuo-spatial sketchpad. It has been revealed that the
phonemic similarity effect has played a significant role in the investigation of the phonological loop.

On the other hand, studies of visual similarity have not found equal importance in the studies of
sketchpad as have the phonemic effect in the phonological loop (Baddeley & Hitch, 1994).

According to Baddeley and Hitch (1994), if it is understood that the sketchpad is a temporary
space for the storage and manipulation of visual and spatial information, it gives a clue that it must
be accomplishing a number of tasks. However, there exists scant research on this aspect of the visuospatial sketchpad. It is expected that the sketchpad may be involved in activities like planning and
executing spatial tasks, keeping track of changes in the visual perception of an individual and
comprehending certain types of visual and verbal information.


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Working memory has been one of the most explored areas of research (e. g., Nairne, 1996).
Various studies have shed light on the structure, function and other aspects of working memory.
Miyake and Shah (1999) suggest that there is a consensus among the researchers exploring this field,
that “working memory is those mechanisms or processes that are involved in the control, regulation
and active maintenance of task relevant information in the service of complex cognition” (pg 1)

Some phenomena found in working memory
In the process of exploring the structure and functions of the working memory, a few
phenomena associated with storage and processing of information were identified (Andrade, 2001).
Articulatory suppression was one of the phenomena associated with working memory (Gathercole &
Baddeley, 1993; Mueller, Seymour, Meyer & Kieras, 2003; Russo & Grammatopoulou, 2003).
According to Murray (1967) articulatory suppression refers to the procedure in which a participant is
required to repeat a syllable aloud while performing a cognitive activity. While doing this, his/her
short-term memory for verbal material would be impaired. According to the working memory theory
(Baddeley & Hitch, 1994) the disturbing effect of articulatory suppression arises because it prevents
the subjects from rehearsing the material. Phonological recoding is disrupted and so the subvocal
rehearsal is disallowed, with the result that the contents of the phonological store cannot be refreshed
and so will decay and be forgotten (Baddeley & Gathercole, 1993).

Another finding is the word length effect, which suggests that individuals have a better short
term memory for shorter words (Baddeley , Thomson & Buchanan, 1975) and vice versa. Long
words take a longer time to be rehearsed and therefore they allow more forgetting (Baddeley, 1999).
To illustrate, ordered serial recall of lists of one-syllable words (e.g., sun, met, hot) was better than


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recall of lists containing five-syllable items (e.g., university, opportunity). Further word length
effects in immediate memory were found both for memory lists presented visually and verbally
(Baddeley & Gathercole, 1993).

Another observation was the irrelevant speech effect in which the recall of verbal material
was disrupted because of the presentation of irrelevant sounds (Graf, Jacob & Hellbruck, 2002).
These sounds could be in the form of any prose, passage, etc being read in any unfamiliar language
or dialect (Baddeley, 1999). Some work related to this effect done is that of Colle and Welsh,
(1976), in which the presence of irrelevant foreign language noise reduced recall performance on
phonologically different lists but not on phonologically similar lists. Another study done by
Baddeley and Salame (1982) found that the use of spoken digits and other irrelevant words could
interfere with the digit span task. Recent research done by Jones (1993) in this area has revealed that
the interfering material need not be speech but could also be any kind of sound that varies in its
pitch.

One of the most important phenomena is the phonological similarity effect first reported by
Conrad and Hull (1964). Baddeley (1966) and Conrad and Hull (1964) demonstrated that when a
participant is presented similar and dissimilar sounding words, the similar words would be harder to
remember. According to Baddeley (1990, p. 72), the memory traces available for the similar
sounding material seem to be harder to discriminate at the time of recall. The phenomenon holds true
when a participant is faced with a task of memorizing a list of words (e.g., cat, mat and rat), letters
(e. g., C, D, B, and V) or even sentences containing similar sounding words.

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As the present study will focus on the phonological similarity effect, the other phenomena
associated with the working memory will not be discussed further. Before discussing the findings
associated with the phonological similarity effect, a discussion of the memory span tasks used in
working memory span tasks used in working memory studies is required.

Simple and complex span tasks
Memory span tasks can be clearly categorized into two main types, simple span tasks and
complex span tasks. The simple span task (Baques & Saiz, 1999) is made use of when the researcher
simply intends to measure the memory span or storage capacity of the individual (e g., Fallon,
Groves & Tehan 1999; Tehan, Hendry & Kocinski, 2001). Keeping in mind the motive of the task,
participants are given a simple cognitive task to perform and then their memory capacity was
measured with the help of their responses.

The best example of the simple span task is the digit span task. In these tests the participants
are asked to memorize a sequence of digits and then recall them in the same order as they were
presented (serial recall) or in any order (free recall). Testing of the digits (Groth & Baker, 2003)
generally began with a sequence of two digits for a variable number of trials after which the number
of digits to be remembered is increased by one. This general procedure has also been used with other
material such as word lists (Postman, Turnage & Silverstein, 1964) and letters (e g., MacAndrew,
Klatzky, Fiez, McClelland & Becker, 2002).

Daneman and Carpenter (1980) were of the view that the simple span tasks and especially
tasks like digit span are capable of measuring only the storage component of memory. In order to


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study the impact of individual differences in the “working” part of working memory a task should be
devised which could measure the processing component as well (see also, La Pointe & Engle, 1990).

This category of task was termed the complex span task. The complex span tasks involve two tasks
which are to be performed simultaneously. One task could be either reading a sentence, solving a
mathematical operation or reading a comprehension passage whereas the second task required
participants to memorize a list of words, letters, etc (Copeland & Radvansky, 2001).

In a simple span task participants are only tested on the storage component of memory in
which they either have to remember letters, words or digits whereas in a complex span task like
reading span the participants were asked to read sentences and are simultaneously required to
remember a list of letters, words or digits. Such a task would involve both the processing and storage
components of memory, in which the participants would be involved in processing the sentences
(processing element of working memory) and at the same time they would be required to memorize
the list of words or digits (storage component of working memory) and recall them when required.
Also the difficulty of the complex span tasks would be obvious from the fact that the memory traces
of the last word of the sentences suffer from resources channeled to perform the simultaneous task
(reading the sentence). In other words, the participants performing the complex span task would not
have all the resources at their disposal to perform any one task (either reading sentences or
memorizing words). Instead, the resources available to perform these two tasks would be divided.
On the other hand, in a simple span task, there would be no such division of resources to perform a
singe task, leading to channeling of all the available resources towards only one task (i.e.,
memorizing the words). It would thus imply that a more difficult simultaneous task like solving
mathematical questions would results in lower recall scores because it would involve a longer


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duration of processing of the material resulting in a greater decay (Towse, Hitch & Hutton, 1998) or
perhaps interference.

There are a few types of complex span tasks found in the studies done in this area. One of the
most frequently used tests was the reading span task. This test was devised by Daneman and
Carpenter (1980) and according to them the aim of the complex span task was to tax both the

processing and storage functions of working memory rather than simply observe the working of
storage functions as traditional digit span or word span tests would do. Participants were given
sentences to read and simultaneously memorize certain list of words provided to them. Their task
then was to recall the last words of each of the sentences read (see also, Siegel, 1994; Daneman &
Tardiff, 1987). For example, if the participant was shown three sentences like:

Non performers who are considered useless are fired by the boss
While surfing on the internet every click leads to another link
For all humans living in the world shelter is a basic need

Participants were asked to read each sentence aloud. Later when instructed, the participant was
required to recall boss, link and need in the same order. The number of words correctly recalled was
expected to indicate the efficiency with which they could comprehend the sentences shown to them
and simultaneously memorize the words at the end of each sentence (Tirre & Pena, 1992; Markovina
& Babic; 2001). Reading span could be mistaken to be a single task but it is not so. The background
task requires the individuals to read a sentence aloud and the primary task needs them to keep a track
of all the words appearing at the end of each of the sentences and recall them at a later stage (La


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Pointe & Engle, 1990; Linderholm & Broek, 2002). This type of test has also been used for other
languages like Japanese (Kondo, Morishita, & Osaka, 1999).

Operation span is another test devised by Turner and Engle (1989) and La Pointe and Engle
(1990). They replaced the sentences in the reading span task with the verification of mathematical
equations. In both the cases, the idea is to make people process something while trying to remember
words. They are provided mathematics questions like, ‘2 + 3 - 6 = ?’ or Is ‘5 \10 + 3 = 2’ ? In the
first example, the participants are required to solve the equation but in the second example they
should solve the equation and say ‘yes’ in case the answer is correct and say ‘no’ in case it is
incorrect. When they verified the equation, they were shown words for example ‘men’ and then they

were shown another similar equation accompanied by another word. When instructed, they were
asked to recall men and other words that followed it, in the same order.

It was observed that simple span task (word span) could not predict reading comprehension
abilities of the individual and also that the simple and the complex word span tasks do not exactly
reflect the same structures, processes or strategies of the memory of individuals (LaPointe & Engle,
1990). In the simple span tasks, the participants were only required to retain items (words, letters or
digits) in short term memory and recall them whenever they were indicated to do so but in the case
of complex span tasks, the individuals had to perform complex cognitive processing simultaneously
while memorizing some items shown to them. Making use of a simple span task in any study is a
good way to measure the storage component of the working memory of the participants. However, in
a simple span task, the participants are only required to memorize either unrelated word lists or lists
of letters and digits; there was no requirement of any kind of comprehension in the way that reading


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text passages or sentences would entail. On the other hand in the complex span tasks, in which the
participants are provided with sentences to read and mathematical equations to solve, the processing
component required to parse these stimuli is engaged. This means that complex span scores included
a component of working memory that would be engaged in reading and comprehension processes. It
is therefore not surprising that reading span measures would also predict reading comprehension
abilities.

The memory span procedure has been the most frequently used technique to estimate the
memory capacity of any individual. The development of complex span tasks to tap processes that
may otherwise not be taxed using simple spans suggests that previously established patterns of
results using simple span tasks may not necessarily be replicated with complex span measures. To
explore any of the characteristics of working memory and its functions, the easiest and the most
convenient way would be to assess the memory of the individuals with the use of both simple and
complex span tasks (La Pointe & Engle, 1990).

Phonological similarity effect
The phonological similarity effect occurs even in the absence of any auditory input and the
presence of only visual inputs. This effect is sometimes also referred to as phonological similarity
decrement (Copeland & Radvansky, 2001), signifying the general trend that similar sounding words
will lead to poorer recall.

The phonological loop gives two explanations for the phenomenon. One of the possible
reasons behind this effect could be that while rehearsing and recalling, the phonological codes of the


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already read material decay more quickly when they are similar (Posner & Konick, 1966) owing to
the fact that phonological confusions arise from the similar sounding words. This confusion leads to
an early decay of phonological codes and leads to worse recall compared to the dissimilar sounding
words. The second possible cause could be that the codes might decay at the same rate regardless of
their similarity, but while recalling them, the partly degraded codes of phonologically similar items
are very difficult to reconstruct and redintegrate (Nairne, 1990). Either of these possibilities would
have possibly led to the lower accuracy of the recall of phonologically similar material in a serial
recall task.

As mentioned earlier the phonological similarity effect has been a well explored
phenomenon. A number of studies have been conducted in the recent years to explore all the
possible aspects and causes of this effect. A study by Fallon et al., (1999) investigates the
phonological similarity effect in a serial recall task. According to their study, “phonological
similarity is observed to affect the serial recall of material detrimentally when correct-in position
scoring is used” (Fallon et al., 1999, pg 301) They conducted two experiments to support the same,
in which they tested the participants using similar and dissimilar lists under immediate recall,
articulatory suppression and filled delay conditions. The results revealed that similar word lists
exhibited better item recall but as far as accuracy of the positions of the items was concerned,

dissimilar lists seemed to be better than the similar ones.

In their study, Lian, Karlson and Winsvold (2001) made use of both words and non words for
analyzing the existence of phonological similarity effect. This effect was studied in the tasks of serial
recall, including a serial recognition and item identification task. The two serial recall experiments


21
demonstrated a significant interaction effect between lexicality (words vs nonwords) and
phonological similarity (phonological similar vs distinct lists) revealing that the sensitivity to
phonological similarity is higher for words than nonwords. In addition to these results, it was also
discovered that in the serial recall tasks, the differences in the scores of similar and dissimilar lists
appeared to be greater for the words than for the nonwords.

Some recent studies have found that phonological similarity does not always lead to a
decrement in memory performance. In the study by Nairne and Kelley (1999), it was shown that the
effect of phonological similarity decrement got reversed i.e., phonologically similar words recalled
better than dissimilar words, in the conditions when participants were given short periods of
distraction activities. It was also observed that there was a better retention for the order of the items
in case of similar instead of dissimilar lists (Nairne & Kelley, 1999).

Another study which emphasizes the existence of the reversal of the phenomenon shows that
‘phonological similarity decrement in immediate serial recall conditions is affected by lexicality of
the list items, type of phonological similarity and scoring methods.’ (Lian, Karlsen & Eriksen, 2004)
The study reveals that the phonological similarity effect appeared in the serial recall score when
phonologically dissimilar words were compared to words which share the middle vowel and the
consonant in the end of the items (e.g., gub, dub, rub, etc) in the lists. Whereas in the second
experiment of the same study it was found that the effect of phonological similarity was absent in the
process of serial recall when the dissimilar words were compared to the words that shared the initial
and final consonants (e. g., gap, gop, gup). The materials used in the first experiment of this study

were similar to the similar words used in the current study, on the other hand the words used in the


22
second study were though not same as dissimilar words used in the current study but were not fully
similar sounding (gAp, gOp, etc.), giving us an insight into the possibility that the phonological
similarity effect is more likely to occur when the items share the rhyme component.

The study by Copeland and Radvansky (2001) also found similar results when they observed
the reversal of the phonological similarity effect in the reading span task. It has been suggested that
sentence contexts may provide additional retrieval cues that may overcome the detrimental effects of
phonological similarity in the reading span tasks. The present study aims to examine this claim in
more detail.

Study by Copeland and Radvansky (2001)
This study compared the performance of participants on phonologically similar and
dissimilar words, using word span and reading span tests. In the first experiment, the participants
were tested for their memory capacity on a word span and reading span task with the use of similar
and dissimilar word lists. For the word span task, the participants were shown three sets of three,
four, five, six and seven words. At the end of each set the participants were required to recall the
words aloud which were then typed by the experimenter. The procedure was similar for the reading
span test also, the only difference being that the participants were presented sets of sentences which
they had to read aloud and then recall the last words of each of the sentence.

The result for the first experiment indicated that in the word span tasks the recall of the
participants exhibited the usual phonological similarity effect. Participants scored higher on the
dissimilar condition than in the similar condition. On the other hand the participants tested on a


23

reading span task displayed an exactly opposite pattern. The results demonstrated that the
participants could recall the similar words better than the dissimilar words presented to them.

It was understood that the obtained results could have been found because a different group
of individuals were tested on the two different span tasks. Perhaps, the results were due to individual
differences and different memorizing and recalling capacities of individuals. In order to overcome
this limitation the same participants were tested on both the word span and the reading span task in a
second experiment and the results obtained again showed that the recall of the participants showed
the existence of the phonological similarity effect in the word span task but exactly opposite results
in the reading span tasks.

The third experiment by Copeland and Radvansky (2001) aimed at reinforcing the idea that
the content of the sentences in the reading span test contributed to the phonological similarity
facilitation in the reading span tasks. In this experiment, the researchers decided to test the
participants on the operation span task because operation span task did not contain any context
related matter. The participants were thus subjected to mathematical problems and were also
required to memorize the words shown to them. Results revealed that the participants scored higher
in the dissimilar conditions than in the similar conditions, showing the traditional phonological
similarity effect.

Only the results for the reading span tests found a reversal of the phonological similarity
effect. Copeland and Radvansky (2001) claimed that the context of the sentences provided cues for
the recall of the words. If compared between the operation span and reading span tasks, “reading


24
span was the only task which included a retrieval cue that was semantically related to the target
word. In the similar condition, for example,

The concert was held by a musician of international fame

The game was going on well when the storm came
The person extracted money from people by using a fake name
the retrieval cue could be coupled with the knowledge that the words in the set rhymed with each
other. However, in the dissimilar condition, for example,

While learning to swim the child drowned in the pool which was deep
The old man did not dispose his cigarette in the bin and dropped the butt
A person who does not like coffee can choose from the many varieties of tea

the rhyme cue was not available, leading to a bad performance” (Copeland & Radvansky, 2001; pg
776).

It was concluded that the usual phonological similarity effect was observed in the operation
span task even though it was a complex span task like the reading span. In the case of operation span
tasks, the content of the mathematical operation was in no way related to the words presented to the
participants. Thus the operation span task did not interfere with the memorizing and recalling of
words. The participants found it easier to recall dissimilar words than similar words. “In case of the
operation and word span tests, although knowledge that the words rhymed with each other existed, it
was not sufficient to provide an effective cue to the participants for recall” (Copeland and
Radvansky, 2001; pg 776). The results obtained from the study clearly indicate a need for future


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exploration into the reasons for such a pattern of results. The word spans followed the already
existing trend of phonological similarity effect. Similar pattern was observed in the operation span
task too. However it is not clear as to why the results for the reading span task were in a totally
opposite direction.

Copeland and Radvansky (2001) suggest that there is a possibility that the above mentioned
pattern of results may be due to the cues emerging from the content of the sentences used in the

reading span task. In other words, the content of the sentences used in the reading span tasks provide
some contextual information to the participants which serves as cues during recall. It was observed
that no such cues were deliberately provided to the participants but they may have emerged from the
content of the sentences themselves in the course of reading the sentences and memorizing and
recalling the words. Having considered the reason suggesting that there is a possibility that the
contextual clues played a significant role during the recall of the words in the reading span task, the
study needed to be extended further to investigate whether context in fact had a role to play in this
study or not.

Context Availability Model
The study by Copeland and Radvansky (2001) suggests directions for a future research in the
area which could provide information on the role of context or any contextual clues in the processing
of complex span tasks like reading span. Having information on this subject could prove to be of
great significance for studies related to the reading span tasks, studies based on phonological
similarity effect and its reversal and also the research based on the importance of context and its