2013. Vol.4, No.3A, 238-245
Published Online March 2013 in SciRes (http://www.scirp.org/journal/psych) http://dx.doi.org/10.4236/psych.2013.43A036
Copyright © 2013 SciRes.
Sequential Stimulus Pairing Procedure for the Students with
Mikimasa Omori1,2*, Jun -ichi Yamamot o3
1Department of P sychology, Graduate School of Human Relations, Keio University, Tokyo, Japan
2Japan Society for the Promoti on o f S ci en c e, Tokyo, Japan
3Department of Psychology , Faculty of Letter, Keio University, Tokyo, Japan
Received December 15th, 2 0 1 2 ; revised January 16th, 2013; accepted February 14th, 2013
For most of students with autism spectrum disorders (ASD) and Williams syndrome (WS), a rare genetic
neurodevelopmental disorder, are known to have intellectual disabilities (ID). Students with ID often
show the difficulties in reading. Especially, they are difficult to acquire the equivalence relations among
pictures, written letters, and sounds and to have fluent eye movement during reading. Previous research
suggested that a student with autism acquired Kanji reading skills by using stimulus pairing training.
However, for acquiring word reading skills, new training which facilitates the fluent eye movement is
necessary and we developed sequential stimulus pairing training. In the present study, we examined the
acquisition of word reading skills through sequential stimulus pairing training for three students with ID
who were also diagnosed as WS and three students with ID who were not diagnosed with WS. In a trial,
each letters, the word, spoken sound, and picture were presented sequentially. With 6 students, result in-
dicated that they could acquire the word reading skills, and also showed the improvement of their eye
movement in reading. The result suggested sequential stimulus pairing training is effective to acquire both
equivalence relations and fluent eye movement for wide range of students with ID.
Keywords: Sequential Stimulus Pairing Procedure; Word Reading; Student with Intellectual Disabilities
Reading is complex behaviors that requires us to pronounce
the letters and words accurately and fluently (Akita & Hatano,
1999), and move our eyes fluently towards the words (Rayner,
2009). The National Reading Panel (2000) in National Institute
of Child Health and Human Development (NICHD) introduced
the five fundamental skills of the acquisition of reading skill.
These are phonetic awareness, phonics, vocabulary, reading
comprehension, and reading fluency. For Japanese reading,
these skills are also required (Akita & Hatano, 1999). By learn-
ing these skills, reading have to be taught (Shaywitz & Shay-
witz, 2008). For students with intellectual disabilities (ID), they
often show the reading difficulties (Allor, Mathes, Roberts,
Cheatham, & Champlin, 2010; Katims, 2001). LaMalfa, Lassi,
Bertelli, Salvini, and Placidi (2004) reported that 70% of per-
sons with autism spectrum disorders have intellectual disabili-
ties and most of individuals with Williams syndrome (WS), a
rare genetic neurodevelopmental disorder, are known to have
mild or moderate intellectual disabilities (Bellugi, Lichtenber-
ger, Jones, Lai, & St. George, 2000). In order to acquire reading
accuracy and fluency, we construct the equivalence relation
among three types of stimuli, pictures, written words and spo-
ken sounds (Omori, Sugasawara, & Yamamoto, 2011; Sidman,
2000; Yamamoto, 1994). However, students with ID with or
without other developmental disabilities often show the diffi-
culties in acquiring these equivalence relations.
Previous study showed that matching-to-sample (MTS) pro-
cedure is one of the most widely used procedures to facilitate
acquiring reading skills and the equivalence relations (e.g.
Stromer et al., 1996; Yamamoto & Shimizu, 2001). However,
there are some potential difficulties for students with ID to
acquire the equivalence relations by using MTS (Dube, et al.,
2010; Pilgrim, Jackson, & Galizio, 2000; Serna, Dube, & Mc-
Ilvane, 1997) because of their attention problems. Recent study
reported that students with ID could acquire the reading skills
by using Direct Instruction flashcard system (Ruwe, McLaugh-
lin, Derby & Johnson, 2011) or stimulus pairing training (Ta-
kahashi, Yamamoto, & Noro, 2011). In other words, it is possi-
ble for students with ID to acquire reading skills by observing
the visual stimuli and listening to the corresponding auditory
stimuli alternatives to c l i c k i n g response.
Takahashi and his colleague (2011) implemented stimulus
pairing training for a student with autism to facilitate Kanji
(Japanese ideogram) reading skills. In their study, a Kanji char-
acter was presented on the computer at first, and then the spo-
ken sound of Kanji character was immediately presented once
simultaneously and other stimulus pairs followed. Through the
training, the student could acquire 12 of Kanji reading and
other equivalence relations. They did not use corresponding
picture stimulus during the training. Other study showed that
stimulus pairing procedure is even more effective to construct
the equivalence relations than MTS procedure when nameable
stimuli were used (Clayton & Hayes, 2004; Leader & Barnes-
Holmes, 2001). And therefore, we decided to use corresponding
We still need to improve stimulus pairing procedure in order
to facilitate the fluent and smooth eye movements toward the
words. Japanese phonogram (Hiragana) usually has one-to-one
M. OMORI, J. YAMAMOTO
relationship between written letters and spoken sounds. For
example, a letter “あ” is only pronounced as //a//. Reading Hi-
ragana letters is not as difficult as reading phonics of English
(Wydell & Butterworth, 1999). However, there are still many
Japanese students struggling to read words. In Ja panese reading,
students were required to move their eyes from top to bottom
and right to left smoothly and fluently. For poor Japanese read-
ers, when a 3-letter-word such as “かえる//kaeru//(frog)” is
presented, they often don’t read a whole word but read one of
three letters, such as “え//e//”. Previous research showed that
poor eye movement is one of the major causes of reading diffi-
culties (Shaywitz, 2003; Stein, 2003; Stein & Talcott, 1999;
Rayner, 2009). Students with autism (Brenner, Turner, & Mul-
ler, 2007) and WS (Braddick & Atkinson, 2011) often tend to
focus on the detailed part of visual stimuli. In other words, poor
readers seem to have fixed eye movement and have difficulties
in moving their eyes fluently for reading.
We then developed the sequential stimulus pairing procedure
to fluent eye movements corresponding to letters. In this train-
ing, a letter of a word was presented sequentially from top to
bottom on the computer display. If we present a letter of a word
in succession from top to bottom, it would be effective for stu-
dents with developmental disabilities to acquire the equivalence
relations and fluent eye movement for word reading skills.
In this study, we examined the acquisition of equivalence re-
lations between pictures, Hiragana words and spoken sounds
for six students with intellectual disabilities through sequential
stimulus pairing training. In the training, the pairs of Hiragana
letters and spoken letters, Hiragana word and spoken word, and
corresponded picture were presented automatically in succes-
sion. Students were required to observe the stimulus pairs pre-
sented. We required the students to read the Hiragana letters
and words presented on the computer and examined whether
the students could acquire the equivalence relations between
Hiragana letters and words and spoken sounds. We conducted
picture naming test in order to evaluate the equivalence rela-
tions between Hiragana words and pictures. We also examined
whether the number of training blocks needed to meet criterion
varied between students with ID who were also diagnosed with
WS and who were not diagnosed with WS.
Six students with intellectual disabilities participated in the
present study. Three of them were diagnosed with Williams
syndrome (WS), two of them were diagnosed with mental re-
tardation (MR), and one of them was diagnosed with autism.
Informed consent was provided to both students and their par-
ents. All of them agreed to participate in the present study. For
students with autism and mental retardation, their diagnosis had
been provided by a doctor or clinical psychologist, individually,
with the criteria of the DSM-Ⅳ-TR (American Psychiatric
Association, 2000). For students with WS, their diagnosis had
been provided by a medical doctor. All students could name a
lot of pictures and read some of Hiragana letters, but could not
read Hiragana words.
Table 1 shows the profiles of the participants. We used
Kyoto Scales of Psychological Development (KSPD; Ikuzawa,
Matsushita, & Nakase, 2002) to assess the students’ develop-
mental quotient (DQ) because we couldn’t assess with the We-
chsler Intelligence Scale for Students-Third Edition (WISC-III;
Japanese edition; Wechsler, 1998) or other standardized test
batteries. Their names have been changed to assumed name to
protect the participants’ identities. For three students with ID
and WS, MANA, GO, and AKI, their mean chronological age
was 5-year-9-month-old ranging 4-year-4-month-old to 7-year-
7-month old, mean DQ in cognition and adaptation (C-A) sub-
scales was 43.33 (SD ± 7.23) ranging 35 to 48, mean DQ in
language and sociability (L-S) subscales was 56.00 (SD ± 10.39)
ra ng i n g 4 4 t o 6 2, and mean full scale DQ was 49. 00 (SD ± 5. 20)
ranging 46 to 55. Their mean verbal age measured by Picture
Vocabulary Test-Revised (PVT-R; Ueno, Nagoshi, & Konuki,
2008) was below 3 years and 0 month old. For three students
with ID and without WS, RUI, KEN, and RYO, their mean
chronological age was 9 year and 3 months old ranging 6-year-
4-month-old to 10-year-3-month-old, mean C-A DQ was 45.00
(SD ± 9.85) ranging 34 to 53, mean L-S DQ was 58.00 (SD ±
7.81) ranging 53 to 67, mean full scale DQ was 51.67 (SD ±
8.50) ranging 43 to 52, and their mean verbal age was 5 years
and 5 months old ranging 3-year- 6-month-old to 6-year-7-
month-old. Both groups were matched with their mean full
scale DQ scores with 49.00 for students with ID and WS and
51.67 for students with ID without WS.
Stimulus and Ap paratus
The experimental procedures for these students were con-
ducted in the lab room in Keio University. A desk and a chair
were used in all experimental phases. In this study, a laptop
computer (Panasonic, Let’s Note CF-S8, Windows XP) was
used to present stimuli. Stimulus pairs for the training phase
Profiles, DQ score, and ve rbal age of students.
Name Sex Chronologic al Age (year; month) Diagnosis C-A DQL-S DQFS DQ Verbal Age (year; month)
MANA Female 4; 04 Williams syndrome 35 62 46 >3; 00
GO Male 5; 03 Williams syndrome 48 44 46 >3; 00
AKI Female 7; 07 Williams syndrome 47 62 55 >3; 00
RUI Male 6; 04 Mental re tardation 53 67 60 4; 01
KEN Male 9; 00 Mental retardation 34 53 43 3; 06
RYO Male 10; 03 Autism 48 54 52 6; 07
Note: Developmental quotient (DQ) scores were measured by using Kyoto Scales of Psychological Development (KSPD; Ikuzawa, Matsushita, & Nakase, 2002). C-A =
cognition and adaptation subscales, L-S = language and sociabilit y subscales and FS = full scales. Verbal age was measured by using Picture Vocabulary Test- Revised
Ueno, Nagoshi, & Konuki, 2008). >3; 00 indicated that the verbal age was below 3 years and 0 month old.. All students are identified by assumed names. (
Copyright © 2013 SciRes. 239
M. OMORI, J. YAMAMOTO
were made by using Microsoft PowerPoint 2007. We prepared
twelve of each 2-letter words, 3-letter words, 2-letter-con-
tracted words, and 3-letter-contracted words. While 2-letter
words have two letters for two sounds (e.g. “いぬ//inu//(dog)”,
“い//i//” “ぬ//nu//”), 2-letter-contracted words have three letters
for two sounds (e.g.”りゅ//ryu//” “う//u//”) . Like as
2-letter-contracted words, 3-letter-contracted words have four
letters for three sounds (e.g.”が//ga//” “びょ//byo//” “う//u//”).
We selected 12 Hiragana words that students were unable to
read at the pre-assessment. Twelve pictures and spoken words
corresponded to each of Hiragana words were also selected.
These Hiragana words and contained Hiragana letters, spoken
words, and pictures were assigned to three stimulus sets. We
prepared three stimulus sets which consisted of eight or 12
Hiragana letters, four Hiragana words, spoken words and pic-
tures. Number of Hiragana letters in a stimulus set varied de-
pending on the 2 or 3 sounds words. Students took training
from the stimulus set 1, and then set 2 and 3 in order.
We conducted pre-assessment, baseline, sequential stimulus
pairing and reading probe after pairing training, and follow-up
for one and two weeks.
Pre-assessment. First, three pictures and three Hiragana let-
ters were presented on the computer one-by-one. The students
were instructed to name the pictures and read letters verbally
presented on the computer for pre-assessment and all students
could name pictures and read letters. After that, forty eight
Hiragana words were presented on the computer one-by-one.
The students were instructed to read them verbally for the word
reading test. The students were also required to name the forty
eight pictures verbally, presented on the computer one-by-one.
These pictures were corresponded to the meanings of the Hira-
gana words. And then, we selected 12 Hiragana words and
corresponded pictures. In addition, we prepared Hiragana let-
ters that were consisted of Hiragana words. For example, when
“かえる//kaeru//(frog)” was chosen as a stimulus, we also se-
lected consisted letters “か//ka//,” “え//e//,” and “る//ru//” as
stimuli. Twelve Hiragana words were ones that students could
not read but could read some of Hiragana letters and name the
corresponded picture at that time, and we prepared these as the
experimental stimulus pairs. If st udents could not name at least
12 pictures, we randomly selected pictures and their corre-
sponded Hiragana words in order to make three stimulus sets.
Baseline. In the baseline, the students took two reading tests
and one naming test. First, they were required to name the 12
pictures verbally, presented on the computer one-by-one for the
picture naming test. And then, they were instructed to read 12
Hiragana words verbally, presented on the computer one-
by-one for the word reading test. After that, they were in-
structed read Hiragana letters consisted of each word verbally,
presented on the computer one-by-one for the letter reading test.
After taking a couple of blocks, they then were required to
name four pictures and read Hiragana letters and four Hiragana
words in a stimulus set. Only when their percentage of correct
response in word reading test in a stimulus set became stable,
we started sequential stimulus pairing training and otherwise,
they remained taking three types of tests.
Sequential stimulus pairing and reading probe after pairing.
During the sequential stimulus pairing, students observed four
stimulus pairs in a stimulus set. Students observed multiple
stimulus pairs of Hiragana letters, spoken letters, a Hiragana
word, a spoken word and a picture for four times. Each pair of
stimuli was presented on the computer simultaneously, and all
the stimulus pairs were presented successively. They were also
required to move their eyes from top to bottom in order to fol-
low the presented letters and a word, and imitate the spoken
letters and a word during the training.
Figure 1 shows the procedure of sequential stimulus pairing
training. When the stimulus set of 3-letter-words, for example
“かえる//kaeru//(frog)”, was on training, the first letter, “か”,
was presented on the upper part of computer display for 2-s and
also its spoken letter was presented. The second letter, “え,”
was presented in the middle, the third letter, “る,” was pre-
sented on the bottom and these spoken letters were also pre-
sented. Finally, the word “かえる”and the spoken word were
presented and the picture of “frog” followed. One trial con-
sisted of the presentation of three Hiragana letters and their
spoken letters for 2-s, a Hiragana word and a spoken word for
2-s, a picture for 2-s and a black screen for 1-s. Each of three
stimulus pairs was presented randomly for three times making
12 trials. It took less than 3-min for students to complete train-
Immediately after finishing a training block, three types of
tests identical to those of the baseline phase were assessed.
They are: picture naming test, word reading test, and letter
reading test. Only when the students could read all four trained
Hiragana words in a stimulus set for two consecutive blocks in
a probe after pairing training phase, they started training for
another stimulus set and repeated until they finished three
stimulus sets. Otherwise, we trained the students on the same
stimulus set again. Although percentages of correct responses
in picture naming test and letter reading test were not 100% nor
stable in reading probe after pairing phase, because our primary
target was to acquire the Hiragana word reading, we didn’t
conduct the further training.
Follow-up phase. Follow-up tests were implemented one and
two weeks after completing the sequential stimulus pairing
training for a stimulus set. The students were required to take
picture naming test, word reading test, and letter reading test.
These tests were identical to the ones conducted in baseline and
probe after pairing training.
The procedure of sequent i a l stimulus pairing training.
Copyright © 2013 SciRes.
M. OMORI, J. YAMAMOTO
Each Hiragana letter and spoken letter and Hiragana word
and spoken word were presented at the same time and then
corresponded picture. Each letters is presented from top to bot-
tom sequentially and successively.
A multiple probe design across behavior (Ledford, Gast,
Luscre, & Ayres, 2008) was used for the present study in
or der to assess the effe cts of sequential stimulus pairing proce-
We prepared three dependent variables in order to evaluate
the emergence of equivalence relation. These were the per-
centages of correct responses in word reading test, picture
naming test, and letter reading test. 1) In word reading test,
students were required to make same vocal responses of the
Hiragana words as the corresponded spoken words presented
during the training when the Hiragana word was presented on
the computer; 2) In picture naming test, students were required
to make same vocal responses of the picture as the corre-
sponded spoken word presented during the training when the
Hiragana word was presented on the computer; 3) In letter
reading test, students were required to make same vocal re-
sponses of the Hiragana letters as the corresponded spoken
letters presented during the training when the Hiragana letter
was presented on the computer.
Due to the characteristics of picture naming test, letter read-
ing test, and word reading test., two independent observers,
including the experimenter, evaluated whether or not a correct
response was made. Both listened as the students spoke and
independently evaluated whether or not the response was cor-
rect. The observers evaluated all trials for each participant.
Trial-by-trial inter-observer agreement (IOA), calculated as the
number of consistent correct responses, was used to determine
interrater reliability. All of the picture naming tests, letter read-
ing tests, and word reading tests in baseline, probe after pairing
training, and follow-ups were evaluated and calculated. The
IOA values were 100% for picture naming test, letter reading
test, and word reading test in baseline, probe after pairing
training, and follow-ups respectively. These values indicate
satisfactory agreement. Kappa (Cohen, 1968) was calculated to
measure interrater reliability for the vocal responses, and was
found to be high for ratings of responses by all students scored
as 1.00 respectively.
Results of Picture Naming Test and Letter Reading
Table 2 showed the mean percentages of correct responses in
picture naming test and letter reading test for students with ID
with WS and students with ID without WS. For three students
with ID and WS, their mean percentages of correct responses in
picture naming tests in all word sets were 50% (SD ± 0.18) in
the last block of baseline, 92% (SD ± 0.18) in the training block
to meet the criteria, 97% (SD ± 0.08) in the 1 week follow-up,
and 75% (SD ± 0.31) in 2 week follow-up block. They also
scored 61% (SD ± 0.14), 99% (SD ± 0.03), 99% (SD ± 0.03),
and 94% (SD ± 0.07) respectively in letter reading tests in all
For three students with ID without WS, they scored 78% (SD
± 0.15) in the last block of baseline, 100% (SD ± 0.00) in the
training block to meet the criteria, 100% (SD ± 0.00) in the 1
week follow-up, and 97% (SD ± 0.08) in 2 week follow-up
block in picture naming test. Their mean percentages of correct
responses in letter reading tests in all word sets were 55% (SD
± 0.12), 93% (SD ± 0.11), 97% (SD ± 0.08), and 94% (SD ±
0.08) respectively in letter reading tests in all word sets.
Results of Word Reading Test in Students with ID
Figure 2 shows the percentages of correct responses in word
reading tests for students with ID and WS, the results of
MANA on the top left panels, GO on the top right, and AKI on
the bottom left panels. Three students took average 8.00 (SD ±
1.73) blocks to complete the three training blocks. The table on
the Figure 2 was the selected stimuli for each student. In the
baseline phase, MANA, on the top left panels, couldn’t read
any of Hiragana words across three stimulus sets but could read
some of Hiragana letters and name most of pictures. We se-
lected 2-letter words as word set 1, 3-letter words as set 2, and
2-letter-contracted words as set 3 for her. She took four training
blocks to meet the criteria for word set 1, two blocks for word
set 2, and three blocks for word set 3. She scored 100% correct
responses in all words sets at the one week follow-up phase.
Her percentages of correct responses in all word sets remained
100% except set 1 (75%). She read “いす//isu// (chair)” when
“りす//risu// (squirrel)” was presented.
GO, on the top right panel, couldn’t read any of words but
could read some of letters and name some of pictures. We se-
lected 2-letter words as word set 1 and set 2, and 3-letter words
as set 3 for him. He took four training blocks to meet the crite-
ria for word set 1, two blocks for word set 2, and three blocks
for word set 3. At the one week follow-up phase, he could read
Mean percentages of correct responses in picture naming test and letter re adi ng test for students with ID with and withou t WS.
Students Test Last block of Baseline Criteria meeting block 1 week follow -up 2 weeks f ol low-up
Picture na ming 50% 92% 97% 75%
with WS Letter reading 61% 99% 99% 94%
Picture naming 78% 100% 100% 97%
without WS Lette r reading 55% 93% 97% 94%
Note: Results in Criteria meeting block were the r esults of last training block i n each word sets.
Copyright © 2013 SciRes. 241
M. OMORI, J. YAMAMOTO
The results of word reading test in students with intellectual disabilities (ID) who were also diagnosed with Williams syndrome (WS). The top
left panels indicated the results of MANA, top right panels indicated the results of GO, and the bottom left panels indicated the results of AKI.
all trained words. In two weeks follow-up phase, his percent-
ages of correct responses in all word sets remained 100% ex-
cept set 1 (75%). Although he could read “し//shi//” in the 2
weeks follow-up sessions, he read “ほひ//hohi// (no meaning)”
when “ほし//hoshi// (star)” was presented.
AKI, on the bottom left panels, couldn’t read any of words
but could read some of letters and name some of pictures. We
selected 2-letter words as word set 1 and set 2, and 3-letter
words as set 3 for her. She took two training blocks each to
meet the criteria for all word sets. At the one and two week
follow-up phase, she scored 100% correct response in all word
Results of Word Reading Test in Students with ID
Figure 3 shows the percentages of correct responses in word
reading tests for students with ID who were not diagnosed with
WS, the results of RUI on the top left panels, KEN on the top
right, and RYO on the bottom left panels. The table on the Fig-
ure 3 was the selected stimuli for each student. Three students
took average 8.00 (SD ± 1.73) blocks to complete the three
training blocks. In the baseline phase, all students couldn’t read
any of Hiragana words across three word sets but could read
some of Hiragana letters and name most of pictures. For RUI
diagnose with MR, on the top left panel, we selected 3-letter
Copyright © 2013 SciRes.
M. OMORI, J. YAMAMOTO
The results of word reading test in students with intellectual disabilities (ID) who were not diagnosed with WS. The top left panel indicated the
results of RUI (MR), to p right panel indicated the results of KEN (MR), and the bottom left panel indicated the results of RYO (autism).
words as word set 1, 2, and 3. He took three training blocks to
meet the criteria for word set 1 and 2 and three blocks for word
set 3. We selected 2-letter-contracted words as word set 1 and
set 2, and 3-letter-contracted words as set 3 for KEN diagnosed
with MR, on the top right panel. He took four training blocks to
meet the criteria for word set 1 and 2 and two blocks for set 3.
For RYO diagnosed autism, on the bottom left panel, we se-
lected 2-letter-contracted words as word set 1 and 3-letter-con-
tracted words as set 2 and 3 for him. He took three training
blocks to meet the criteria for word set 1 and two blocks for set
2 and 3.
For three students without WS, their percentages of correct
responses in all word sets were remained 100% in one and two
week follow-up phase.
In this study, we examined the acquisition of equivalence re-
lations among pictures, Hiragana words and spoken sounds for
six students with intellectual disabilities through sequential
stimulus pairing training. During the training, students were
required to observe the stimulus pairs of Hiragana letters and
spoken letters, Hiragana word and spoken word, and corre-
sponded picture. According to Table 2, Figures 2 and 3, all
students established equivalence relations between pictures,
Hiragana words and spoken sounds through sequential stimulus
Copyright © 2013 SciRes. 243
M. OMORI, J. YAMAMOTO
pairing training. Our results replicate the previous finding that
equivalence relations (Clayton & Hayes, 2004; Leader & Bar-
nes-Holmes, 2001), Kanji reading skills (Takahashi et al., 2011)
and sight word reading (Ruwe et al., 2011) can be acquired by
observing visual stimuli such as stimulus pairing training and
flashcard training. Each student acquired t at least 12 Hiragana
words reading through the training. We demonstrated that pre-
senting each letter on top, middle, and bottom in order can be
applied to the sequential stimulus pairing training and facili-
tated the acquisition of Hiragana word reading. And we ex-
tended the previous results by demonstrating that students with
ID who were also diagnosed with autism, WS, and MR could
acquire the multi-letters word reading skill through sequential
stimulus pairing training while previous study showed a student
with autism could acquire one-letter Kanji reading skill (Taka-
hashi et al., 2011).
We also examined whether the number of training blocks
needed to meet criterion varied between students with ID who
were also diagnosed with WS and who were not diagnosed with
WS. Based on Figures 2 and 3, mean number of training blocks
to complete the all word sets in both students with ID with and
without WS was 8.00 (SD ± 1.73) blocks respectively. These
results suggested that sequential stimulus pairing training was
effective for students with ID even though s/he was also diag-
nosed other kinds of developmental disabilities. While MTS
procedure requires students to respond by clicking (e.g. Stromer
et al., 1996; Yamamoto & Shimizu, 2001), sequential stimulus
pairing training only required them to observe the presented
visual stimuli. Without clicking responses, we can decrease the
potential difficulties of acquiring equivalence relations for stu-
dents with ID through MTS procedure, such as position prefer-
ences and stimulus preferences. Previous studies showed that
stimulus pairing training is more effective to acquire the equi-
valence relations than MTS procedure when nameable stimuli
were used (Clayton & Hayes, 2004; Leader & Barnes-Holmes,
2001). There are five fundamental skills of acquiring reading
skills, phonetic awareness, phonics, vocabulary, reading com-
prehension, and reading fluency (Akita & Hatano, 1999; NRP,
2000). Table 2 showed that our students could read about half
of Hiragana letters containing in Hiragana words even at the
baseline phase. They could also more than half of picture stim-
uli. We still need to examine whether students with ID who
could not read any of Hiragana letters containing in the words
can also acquire the equivalence relations and reading skills
through sequential stimulus pairing training. Although further
research is necessary, letter reading skill is one of the pre re-
quirement skills for acquiring Hiragana word reading and fluent
eye movements like as the developmental stages of the acquisi-
tion of reading skills (Akita & Hatano, 1999; NRP, 2000).
Because poor eye movements is one of the major cause of
reading difficulties (Stein, 2003; Stein & Talcott, 1999), our
training were focusing on the not only the acquisition of equi-
valence relations, but also fluent eye movement toward the
words. All students could not read none of Hiragana words but
some of letters at the pre assessment. For example, when these
students with ID were required to read “かえる//kaeru//(frog)”,
they often responded by reading only “え//e//” and others read
“る//ru//” as a vocal response. According to Figure 2, MANA
could acquire not only 2-letter words reading skill, but also
3-letter words and 2-letter-contracted words reading skills. AKI
also extended her reading skills from 2-letter words to 3-letter
words reading. While others extended their reading skills through
the training, GO could only acquire 2-letter words reading skills
because his L-S DQ (44) was the lowest of three. However, he
did show untrained 3-letter words and 4-letter words reading
skills after finishing the present study. All of students with WS
could read 11 of 12 learned words even 2 weeks after the train-
ings. Based on Figure 3, RUI acquired 3-letter words reading.
KEN and RYO extended their reading skills from 2-letter-con-
tracted words to 3-letter-contracted words. Three students with-
out WS could read all of their learned words even after 2 week
follow-up phase. Although students with ID often have diffi-
culties in attending visual stimuli and moving their eyes flu-
ently (Braddick & Atkinson, 2011; Brenner et al., 2007), they
acquired at least 2-letter words reading by using sequential sti-
mulus pairing procedure.
MANA, KEN, and RYO even acquired contracted word
reading. A contracted letter is made of one big letter and one
small letter. Reading contracted word is sometimes difficult for
typically-developing students because contracted letters can be
discriminated only by the size of second letter. For example,
MANA read “しやつ//shiyatsu//” when “しゃつ
//shiatsu//(shirt)” was presented on the computer at the last
block of baseline phase in word set 3. Although she had already
learned how to read 3-letter words through our training, it was
still hard for her to read contracted-letters and words. In order
to facilitate the contracted word reading, we surrounded each
normal and contracted-letters by black framed white rectangle
(see Figure 1). By boxing off the each word, visual cue helped
students to read a letter or a contracted-letter in a box for one
The theoretical implication of our study was that we showed
the establishment of reading skills by contiguities, as well as by
contingencies, normally focused using MTS procedure. During
the developmental process, we suppose students learn language
and literacy through contiguity in naturalistic and educational
situations. Furthermore, as for an applied implication, our study
with sequential stimulus pairing procedure demonstrated the
efficient and effective, learning method to students: we required
neither choice response nor differential responding for students’
tasks. By using our procedure, students with ID who also diag-
nosed with genetic disorder, such as Williams syndrome, or
developmental disabilities, such as autism could acquire the
reading skills. It suggests that we can apply the sequential
stimulus pairing procedure for wide range of students with ID
who have some repertoires to read letters and name pictures in
order to facilitate their reading skills. Future studies need to
examine effective observing responses for getting students’
attention and maintain their stimulus pairing tasks. Ruwe and
her colleague (2011) reported that flashcard system could fa-
cilitate not only word acquisition, but also passage reading. In
sequential stimulus pairing procedure, we presented each letter
of the word one-by-one to extend students’ reading skills. And
then we can apply the sequential stimulus pairing procedure to
sentence or passage reading and comprehension by presenting
each word or segment of the sentences one-by-one sequentially.
In order to firm the “logical structure” of reading skills from
letter reading to reading comprehension in this paradigm, we
also need to clarify what prerequisites and pre-skills are neces-
sary for learning.
This work has been supported by Global Center of Excel-
Copyright © 2013 SciRes.
M. OMORI, J. YAMAMOTO
Copyright © 2013 SciRes. 245
lence (GCOE) program and Japan Society for the Promotion of
Science (JSPS). This work was permitted by Keio University
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