digraphs did not seem to have the same effect on the
order when they are mastered. Diphthongs seemed to
be mastered at the end of the second grade, while
digraphs were still a little difficult at the end of the
third grade. Therefore, having the same number of
letter does not seem to be the only factor at play.
Another factor seems to be the ease at which children
grasp the mapping between the diphthongs and
digraphs on the one hand, and the phonemes on the
other hand. It is proposed that the earlier mastery of
diphthongs is because the glide in diphthongs may
have been easier to understand by children due to the
transparent mapping between the two glided sounds
and the two letters in the diphthongs.
The digraphs, in turn, may have been more
difficult because the sounds that the digraphs map to
are not directly evident. There are two possible routes
to memorizing this mapping: analysis and
memorization. The children may have analyzed, in
the case of the digraph <ng>, the letter <n> maps to
an alveolar nasal consonant, the letter <g> maps to a
velar plosive consonant, and <ng> map to /ŋ/ which
is a velar nasal consonant, a consonant with the same
manner of articulation as /n/ and the same place of
articulation as /g/. There are features that are shared
by /n/ and /g/ on the one hand, and /ŋ/ on the other
hand. Once children have done the analysis and
arrived at the correct conclusion based on a good
match with an entry in their lexicon, they may have
started to remember, for instance, the pairing between
the written word <bunga> with the lexical entry
bunga in their lexicon. This memorization may then
lead to them reading not the single letters of the
diphthongs, but the phoneme that each of the
diphthongs maps to.
Consonant clusters seemed to present the ultimate
difficulty as shown by the findings that at the end of
third grade, children still made considerable
proportion of miscues to words containing consonant
clusters. A possible explanation is because there are
many more consonant clusters than there are
diphthongs and digraphs, children took longer to
establish the mapping between consonant clusters and
the phonemes that they represent. In other words, the
greater number of kinds of consonant clusters adds
more challenge, in addition to the clusters having two
graphemes which render the clusters having more
sounds than diphthongs and digraphs.
The above findings go along the lines of those of
Marinus and de Jong (2008). Although using a
different method, it was demonstrated that digraphs
are utilized by beginning readers when they read and
they do influence the details of the syllable structures
that are mastered by children as they progress from
grade one to grade three of primary school.
Furthermore, findings about word length effect that
has been observed previously was also observed in
the current investigation. In line with Zoccolotti et al.
(2005) end of grade three seemed to be the point at
which children are not very much influenced by the
longer diphthongs and digraphs. In addition, the
current results expand the work of Anjarningsih
(2016) in that the consonant clusters continue to
present challenges even up to the end of grade three.
However, the findings about consonant clusters
may raise some questions before they can be
confidently interpreted. There is of course a
difference between digraphs and diphthongs on the
one hand, and consonant clusters on the other hand:
while diphthongs and digraphs map to one phoneme,
consonant clusters map to two or more phonemes, one
for each of the graphemes or letters in the clusters.
While this mapping, intuitively, may seem to predict
that consonant clusters should be easier to master than
digraphs because once children can map single
consonant graphemes to their corresponding
phonemes, they should get the pronunciation of
clusters correctly, our current findings go against this
prediction. Whether the visual and regularization
miscues were caused by children expecting to find
simple consonants followed by simple vowels in
syllables remains to be tested further.
With the above findings at hand, it interesting to
see that children did not master all the tested
disyllabic words at about the same time. They needed
to practice reading for about three years before their
reading performance became accurate. The sub-
lexical details or in this case, the syllabic make-up of
the words did influence how accurate children read
the words. Therefore, in a transparent orthography
such as the Indonesian orthography investigated here,
the mapping between graphemes and phonemes in
“irregular” diphthongs, digraphs, and consonant
clusters influences how early children can read
highly-frequent disyllabic words. Syllabic
complexity and orthographic depth, just like the
findings of Seymour et al. (2003), also influence the
rate of reading development in Indonesian.
It should be noted that the syllabic structures
tested in the current investigation do not comprise all
syllabic structures in Indonesian. In addition to CV or
CVC, Indonesian also has VC which can be written
by vowel and consonant graphemes or just vowel
graphemes (e.g., in the word <dua> meaning “two,”
the grapheme <a> maps to /wa/). Furthermore,
trisyllabic and words with more syllables also exist in
Indonesian, both monomorphemic (e.g., udara “air”)
and polymorphemic (e.g., penggorengan “frying