Edited by: Harald Clahsen, Potsdam Research Institute for Multilingualism, Germany
Reviewed by: Davide Crepaldi, University of Milano-Bicocca, Italy; Stavroula Stavrakaki, Aristotle Univeristy of Thessaloniki, Greece
*Correspondence: Naama Friedmann, Language and Brain Lab, School of Education and Sagol School of Neuroscience, Tel Aviv University, Ramat Aviv, Tel Aviv 69978, Israel
This is an open-access article distributed under the terms of the Creative Commons Attribution License (CC BY). The use, distribution or reproduction in other forums is permitted, provided the original author(s) or licensor are credited and that the original publication in this journal is cited, in accordance with accepted academic practice. No use, distribution or reproduction is permitted which does not comply with these terms.
We explored morphological decomposition in reading, the locus in the reading process in which it takes place and its nature, comparing different types of morphemes. We assessed these questions through the analysis of letter position errors in readers with letter position dyslexia (LPD). LPD is a selective impairment to letter position encoding in the early stage of word reading, which results in letter migrations (such as reading “cloud” for “could”). We used the fact that migrations in LPD occur mainly in word-interior letters, whereas exterior letters rarely migrate. The rationale was that if morphological decomposition occurs prior to letter position encoding and strips off affixes, word-interior letters adjacent to an affix (e.g., signs-signs) would become exterior following affix-stripping and hence exhibit fewer migrations. We tested 11 Hebrew readers with developmental LPD and 1 with acquired LPD in 6 experiments of reading aloud, lexical decision, and comprehension, at the single word and sentence levels (compared with 25 age-matched control participants). The LPD participants read a total of 12,496 migratable words. We examined migrations next to inflectional, derivational, or bound function morphemes compared with migrations of exterior letters. The results were that root letters adjacent to inflectional and derivational morphemes were treated like middle letters, and migrated frequently, whereas root letters adjacent to bound function morphemes patterned with exterior letters, and almost never migrated. Given that LPD is a pre-lexical deficit, these results indicate that morphological decomposition takes place in an early, pre-lexical stage. The finding that morphologically complex nonwords showed the same patterns indicates that this decomposition is structurally, rather than lexically, driven. We suggest that letter position encoding takes place before morphological analysis, but in some cases, as with bound function morphemes, the complex word is re-analyzed as two separate words. In this reanalysis, letter positions in each constituent word are encoded separately, and hence the exterior letters of the root are treated as exterior and do not migrate.
Major questions in the study of morphological processing are whether and when morphological decomposition takes place during reading. Since the seminal work of Taft and Forster (
In the current study, we ask when and how this morphological decomposition takes place using letter position encoding. Specifically, we ask about the interaction between letter position encoding and morphological decomposition, and their relative order. Until now, studies that asked questions about morphological decomposition by using letter transpositions examined priming in normal readers. The basic idea of many of these studies was to compare the priming of primes created from existing words by transposition within the stem to primes created by transposition across morpheme boundaries. A difference in the priming effect of the two conditions would indicate that morphological decomposition occurs early. These studies yielded inconsistent results (Christianson et al.,
In the current study we looked at morphological decomposition through letter position from a novel perspective: that of the reading pattern of individuals with letter position dyslexia (LPD), a dyslexia that specifically affects letter position encoding. The rationale is the following: LPD affects an early, pre-lexical stage of orthographic-visual analysis (for these model components c.f., Ellis and Young,
Previous studies have already examined the interaction of morphological decomposition and peripheral dyslexias—dyslexias in the pre-lexical orthographic-visual analysis stage. Reznick and Friedmann (
A similar effect of morphology on peripheral dyslexia was found in the reading errors of 10 individuals with developmental attentional dyslexia (Friedmann et al.,
Neglexia and attentional dyslexia both stem from a pre-lexical deficit at the orthographic-visual analyzer: neglexia affects attention shift to the neglected side of the word and attentional dyslexia affects binding of letters to words. Therefore, the findings of both studies serve as an additional evidence that morphological decomposition indeed occurs very early in the course of word reading, before lexical access.
The current study assessed a different function of the orthographic-visual analysis stage, which possibly functions at an earlier stage than letter-to-word binding
We used the fact that individuals with LPD make transpositions in middle letters but almost never in the first or final letters. The idea was that if the morphologically-complex word is decomposed to its morphemes prior to the stage at which letter position errors occur, then the exterior letter of the base morpheme that is adjacent to an affix and therefore appears as a middle letter in the complex word, may become an exterior letter when stripped of the affix. For example, in a word like
Namely, if both conditions are fulfilled: morphological decomposition occurs before letter position encoding, and this decomposition actually creates two separate morphemes, then letter position errors are not expected to occur in base letters on the edge of an affix (or are expected to occur in a rate similar to that of exterior letters). If, however, letter position encoding (and hence, letter position errors) occurs prior to the early morphological decomposition, then at the level in which letter position errors occur, the first letter of the second morpheme is still in middle position, and would have a similar fate to other middle letters. In this case, it will show the same transposition rate as middle letters. To examine this question and to compare various types of morphemes, we used Hebrew, a morphologically-rich language.
Hebrew is a Semitic language, read from right to left. It is an alphabetic script in which not all vowels are represented orthographically. Hebrew words are built from a 3-letter root and a derivational template and/or inflectional morphology. Verbs, nouns, adjectives, and prepositions can inflect for gender, number, and possessor/genitive. Verbs also inflect for tense and person. Derivational templates exist for verbs, nouns, and adjectives. The nominal template for nouns and adjectives is called “mishkal” and the verbal template for verbs is called “binyan” (Arad,
As shown in Appendix A Table
The participants were 11 individuals with developmental LPD and one woman with acquired LPD following brain damage. Galia, the participant with acquired dyslexia, was a 54 years old woman. She was a teacher and a PhD student with 20 years of education. She had a sudden onset of seizures with herpes encephalitis 13 months before our testing. CT demonstrated a small hypodense area in the right temporal lobe. Her reading was impaired, showing clear and selective LPD. Her speech and naming abilities were normal. Her writing was impaired, with mild graphemic buffer dysgraphia. She participated only in Experiment 1, in which the participants read aloud 500 migratable words. The background details of the developmental LPD participants, who were all school students, 5 females and 6 males, are summarized in Table
YO | 18;1 | M | 12 |
OR | 13;11 | M | 8 |
BR | 13;7 | M | 7 |
MR | 12;2 | F | 6 |
EL | 11;6 | M | 6 |
AD | 11;1 | M | 6 |
TL | 11;5 | M | 6 |
SK | 11;7 | F | 5 |
AF | 11;5 | F | 5 |
YV | 11;0 | F | 5 |
TA | 10;5 | F | 5 |
Each of the participants with LPD was selected to participate in this study on the basis of migration errors within words in reading aloud and in silent reading, alongside intact word production. This screening testing included two tasks of reading aloud: the TILTAN screening test of oral reading of 136 single words of various types, and a test of oral reading of 232 migratable words. To establish that the migrations that the participants made in reading indeed resulted from a deficit in letter position encoding and not in the speech production stages, we also used tasks of reading without oral production: a test of migratable word comprehension, and tests of oral production without reading: picture naming and migratable word repetition. We only included participants who made migrations in reading aloud and in comprehension and who had no migrations in oral word production.
The
For individuals who made significantly more migration errors than controls, without other dyslexias, who were therefore suspected to have LPD, we further administered an additional reading aloud test of 232 migratable words.
The
To establish that the impairment is at the early stage of orthographic-visual analysis rather than in the output stages, we also tested reading comprehension of migratable words, picture naming, and the repetition of 20 migratable words. The rationale was that if the deficit is at the orthographic-visual analysis stage, not only reading aloud but also comprehension of migratable words would be impaired and indicate transpositions of middle letters, but picture naming and repetition should not be affected. An output deficit should show the opposite pattern, with good comprehension of written migratable words when no reading aloud is required, and poor oral production in picture naming and repetition.
We selected only participants who had significantly more letter migration errors on the three tasks of migratable word reading than age-matched skilled readers (TILTAN norms, Friedmann and Gvion,
Table
Developmental | |||||||||
YO | 7 |
6 |
1 | 0 | 0 | 0 | 1 | 0 | 0 |
OR | 22 |
4 | 4 |
0 | 0 | 1 | 5 |
1 | 0 |
BR | 18 |
5 | 1 | 0 | 0 | 1 | 1 | 0 | 0 |
MR | 11 |
9 |
3 | 2 |
0 | 0 | 0 | 3 |
0 |
EL | 13 |
8 |
1 | 2 |
0 | 0 | 3 |
2 | 0 |
AD | 6 |
3 | 0 | 0 | 0 | 0 | 0 | 0 | 0 |
TL | 20 |
5 |
4 |
2 |
1 | 5 |
6 |
5 |
0 |
SK | 17 |
5 |
3 | 1 | 0 | 0 | 1 | 0 | 0 |
AF | 21 |
2 | 3 | 2 |
0 | 1 | 2 |
0 | 0 |
YV | 13 |
4 | 1 | 1 | 0 | 0 | 0 | 1 | 0 |
TA | 14 |
12 |
3 | 2 |
1 | 2 |
5 |
1 | 0 |
Acquired GALIA | 15 |
4 | 0 | 0 | 0 | 0 | 0 | 0 | 0 |
Average | 14.8 | 5.6 | 2.0 | 1.0 | 0.2 | 0.8 | 2.0 | 1.1 | 0 |
YO | 13 |
12 |
OR | 27 |
50 |
BR | 10 |
34 |
MR | 7 |
37 |
EL | 13 |
22 |
AD | 9 |
19 |
TL | 15 |
25 |
SK | 27 |
34 |
AF | 24 |
56 |
YV | 12 |
44 |
TA | 27 |
50 |
Acquired GALIA | 22 |
59 |
Average | 17.2 | 36.8 |
In reading aloud, as can be seen in Tables
The comprehension of migratable words, which involved only silent reading, also indicated that the participants had LPD, as each of them made significantly more errors than the controls in this test.
Unlike their impaired oral and silent reading, characterized by migration errors, the participants' naming and migratable word repetition was normal, and none of the participants made migration errors in naming or in repetition. Table
YO | 98 | 100 |
OR | 98 | 100 |
BR | 100 | 100 |
MR | 96 | 100 |
EL | 99 | 100 |
AD | 100 | 100 |
TL | 99 | 100 |
SK | 99 | 100 |
AF | 97 | 100 |
YV | 99 | 100 |
TA | 98 | 100 |
This pattern of results shows that indeed the source of the migration errors of the 12 participants lies in the encoding of letter position in the orthographic visual analyzer.
The control group included 25 age-matched skilled readers without any reading impairments, as tested by the
The experimental study of morphology in LPD included six experiments that tested reading, lexical decision, and comprehension of migratable words in two levels: single words, and sentences that include migratable words.
During the testing sessions, every response that differed from the target was transcribed by the experimenter, and words read correctly were scored with a plus sign. All the sessions were audio-recorded and two judges listened to the recordings after the sessions, and the transcription from the session was checked and corrected or completed using the recordings.
The words and sentences in the various experiments were presented to each participant over the desk, printed on a white page. In the oral reading tasks, the participant was requested to read aloud as accurately as possible; in the lexical decision and comprehension tasks the participant was requested to perform the task without reading the words aloud. No time limit was imposed during testing, and no response-contingent feedback was given by the experimenter, only general encouragement. The participants were told that whenever they needed a break they can stop the session or take a break. Each participant was tested individually in a quiet room in two to three sessions of 1–2 h. The Ethics Committees of Tel Aviv University and the Ministry of Education approved the experimental protocol.
The results were analyzed on the group level as well as for each individual participant. We compared the performance at the group level between two conditions using
At the individual level, performance in different structures was compared using Chi square test. To compare the performance of each experimental participant to her/his age-matched control group, we used Crawford and Howell's (
Across all 6 experiments, we examined three types of morphemes: Inflectional, derivational, and bound function morphemes (conditions 1–3 below). In all cases, we examined the rate of transpositions of root letters AB that were adjacent to the tested morpheme, compared with a control condition in which the root letters AB were exterior
In 1–4 below, ABX represent the three consonant root letters. In all the target words, the two letters to be migrated, A and B, were always adjacent to each other, and the transposition of the letters AB created an existing word with the sequence BA in the relevant side.
Condition 1: Inflectional morphology | |
a. in the beginning: | [inflectional morpheme] |
b. in the end: | X |
Condition 2: Derivational morphology | |
a. in the beginning: | [derivational morpheme] |
b. in the end: | X |
Condition 3: Bound function morpheme | |
in the beginning: | [bound function morpheme] |
Condition 4: Exterior letter migration, with no morpheme on the relevant side | |
a. in the beginning: | |
b. in the end: | (possibly a morpheme here)X |
We followed several procedures and principles when creating the list of words of the various types: we used the same root for the various conditions, in most cases (72% of the roots) the same root was used in all 4 conditions or in 3 conditions, except when the root does not naturally appear with some of the morpheme types. That way, in many cases it was exactly the same root and the same two letters that migrated in the compared conditions. For example, the 3-letter root
The derivational morphemes were morphemes of verbal and nominal templates, the inflectional morphemes were morphemes of person, gender, number, tense, and possessive pronoun suffixes.
The Hebrew bound function morphemes always appear before the root, and so they did in the stimuli. We used the 7 bound function morphemes, in a way that they always formed a syntactically licit combination with the word they were bound to (e.g., the determiner “the” and the preposition “in” were always added to a noun or an adjective but not to a verb).
In the bare root control condition, we used the 3-letter root itself, when it was an existing word. In the morphologically complex exterior letter migration condition, we used the root and an additional affix that appeared on the side opposite to the expected migration—if the expected exterior migration was on the beginning, in letters 1 and 2 of the root, the affix was added at the end of the word, and if the expected migration was at the end, the affix was added in the beginning of the word, before the root. The morphologically complex control condition also included vowel letters inside the words, but not between the migrating letters, which were always adjacent. The longer control stimuli were used so that exterior letter migration would be tested in words of the same length as the words in the morphological conditions.
In Hebrew, five letters have different forms in middle and final position, so in order to avoid the effect of letter form on position encoding (see Friedmann and Gvion,
Morphologically complex words were classified to the various conditions according to the type of morphemes that were adjacent to the site of expected migration. Namely, if a word started with an inflectional prefix and ended with a derivational suffix, it was considered part of the inflectional condition if the relevant migration was adjacent to the prefix (root letters 1 and 2), and part of the derivational condition if the relevant migration was adjacent to the suffix (root letters 2 and 3). In some of the word lists there were few words that had a potential for both migrations of the first and second root letters and the second and the third root letters. In these cases, we included these items in the totals of both conditions, and analyzed the errors according to the errors each participant made. The words of the various conditions were presented in a semi-random order, making sure that no more than two words of the same condition appeared consecutively, and that words of the same root (and even words with the same root letters in a different order) never appeared consecutively.
To assess the effect of the morphological structure of the word on the rate of migrations, we compared the rate of migrations of the two root letters (AB) in each of the three types of morphemes to the exterior migration
We used three types of tasks: oral reading, lexical decision, and written word comprehension. Because we had initially thought that some morphological analyses may occur only within a sentence context, we examined each task both on the single word level and in the sentence level, with a total of six experiments. (As you will see below, this worry was unwarranted, as morphological decomposition occurred even at the single word level). The group with LPD read a total of 8679 morphologically complex migratable words in the 6 experiments. Together with the initial lists of migratable words that each participant read in the screening stage, each participant read 1136 migratable words, so our results are based on a total of 12,496 migratable words that the LPD group read.
Each participant was presented with a list of 500 words and was requested to read them aloud as accurately as possible. The word list included:
1 | Initial bound function morpheme | the-thief → the-Negev, southern Israeli region | |||
2a | Initial inflectional morpheme | drive-out-3sg-mas-future → excite-3sg-mas-future | |||
2b | Final inflectional morpheme | dogs → cables | |||
3a | Initial derivational morpheme | sneaked-3sg-mas-refl → dried-3sg-mas-refl | |||
3b | Final derivational morpheme | liar → Guinea pig | |||
4a | Control initial exterior letter | pile → mane | |||
4b | Control final exterior letter | screwdriver → make-older |
The control items were
The results, summarized in Table
YO | 15 |
24 |
3 |
1 |
OR | 19 |
21 |
1 | 3 |
BR | 13 |
11 |
1 | 1 |
MR | 7 |
12 |
3 |
3 |
EL | 12 |
13 |
3 |
5 |
AD | 11 |
17 |
1 | 0 |
TL | 15 |
8 |
4 |
3 |
SK | 27 |
31 |
9 |
4 |
AF | 16 |
18 |
7 |
4 |
YV | 9 |
15 |
2 |
2 |
TA | 24 |
21 |
3 |
8 |
Galia (Acquired) | 27 |
27 |
1 | 4 |
LPD Average ( |
16.2 (6.9) | 18.2 (6.9) | 3.1 (2.7) | 3.2 (2.1) |
12th graders | 1.2 (0.4) | 1.7 (2.0) | 0.3 (0.5) | 0.2 (0.2) |
7–8th graders | 0.9 (1.1) | 1.6 (1.5) | 0.2 (0.4) | 0.05 (0.1) |
5–6 graders | 1.1 (0.04) | 4.0 (2.3) | 0.3 (0.2) | 0.1 (0.3) |
The same tendency was found for each of the individual participants. All individuals made significantly (
Another finding sheds light on the early morphological analysis that occurred in the reading of our LPD participants: In total, across all 11 developmental LPD participants in reading all 500 migratable words, there were 58 exterior letter migrations in which two consonant letters transposed (1% of the words they read). None of these involved a root letter transposing with a letter that belonged to the bound function morpheme (or, in fact, any non-root morpheme). Even if we take only words in which an exterior transposition creates an existing word, there were 34 words (a total of 408 target words for all LPD participants) that started with a bound function morpheme, in which a transposition of the letter of the function morpheme and the first letter of the root could create an existing word (e.g., OBDK, vebadak, and-checked, that could create BODK, bodek, checks). However, this error occurred only once—only one participant made one such exterior migration across a morpheme boundary. This supports the conclusion that letter position errors occurred later than the morphological decomposition of the function morpheme from the word to which it was bound.
Additional analyses that explored decompositions and letter position errors in words in which the same letter can function in two different morphological roles are reported in Appendix B).
Similarly to the participants with developmental LPD, Galia (see Table
Both the developmental and the acquired LPD participants made significantly more transposition errors near inflectional and derivational morphemes than near bound function morphemes, and their transpositions near bound function morphemes were as scarce as exterior transpositions. No differences were found between the rate of transpositions near inflectional and derivational morphemes. These results indicate that some form of very early morphological decomposition applies to bound function morphemes, at the same time or before letter position encoding takes place. As a result of this early analysis, the bound function morpheme is stripped off the base word, so that the letters at the edge of the word that are adjacent to the bound function morpheme are treated as exterior letters, and hence, very few transpositions occur in them.
Experiment 1 indicated that when words are presented in isolation, there is an effect of early morphological decomposition on migrations in oral reading. Experiment 2 tested the effect of morphology on migrations in oral reading of migratable words in sentences.
The target words were migratable words in which a transposition of root letters could occur adjacent to inflectional, derivational, or bound function morphemes. The test included 30 sentences: the
(5)
(6)
(7)
The migratable words in the different conditions did not differ in frequency [
Error analysis focused solely on migrations in the relevant target words. We removed from the analyses 7 sentences in which the participant made an irrelevant (non-transposition) error on the target word.
The results of the reading aloud of migratable word within sentences are summarized in Table
YO | 38 |
14 | 27 |
21 |
OR | 50 |
14 | 33 |
21 |
BR | 14 | 29 |
21 |
0 |
MR | 38 |
14 | 27 |
0 |
EL |
13 | 0 | 7 | 0 |
AD | 25 |
14 | 20 |
7 |
TL | 25 |
33 |
29 |
14 |
SK | 25 |
57 |
40 |
14 |
AF | 25 |
14 | 20 |
14 |
YV | 25 |
29 |
27 |
8 |
TA | 38 |
43 |
40 |
17 |
LPD Average ( |
28.7 (11.2) | 23.7 (16.3) | 26.5 (9.5) | 10.5 (8.1) |
12th graders | 2.5 (5.6) | 5.7 (7.8) | 4.0 (3.7) | 2.9 (3.9) |
7–8th graders | 7.5 (8.7) | 5.7 (7.4) | 6.7 (6.3) | 0.7 (2.3) |
5–6th graders | 3.8 (6.0) | 12.9 (8.1) | 8.0 (4.2) | 1.4 (4.5) |
After we established the clear effect of the morphological structure of the target word on the rate of transpositions on the edge of the root in oral reading, we moved to assess whether the same effect is present also in reading tasks that do not involve reading aloud. Experiments 3 and 4 tested migrations in a lexical decision task at the single word and sentence level respectively.
The stimuli list for lexical decision included 105 items: 59 pseudowords and 46 non-migratable real words. The pseudowords included: 20 pseudowords derived from real words by transpositions of the root letters next to an inflectional morpheme (Table
1a | Initial inflectional morpheme | photograph-3sg-mas-fut | ||||
1b | Final inflectional morpheme | receive-past-2pl-mas | ||||
2a | Initial derivational morpheme | weight | ||||
2b | Final derivational morpheme | department | ||||
3a | Control initial exterior letter | forgave-2nd-pl | ||||
3b | Control final exterior letter | receive-1st-pl-fut |
The results of the lexical decision task, summarized in Table
YO | 10 |
30 |
11 | 0 |
OR | 35 |
25 |
11 |
7 |
BR | 40 |
45 |
5 | 0 |
MR | 10 |
5 | 0 | 11 |
EL | 15 |
40 |
0 | 4 |
AD | 15 |
40 |
0 | 4 |
TL | 15 |
20 |
16 |
0 |
SK | 70 |
75 |
32 |
0 |
AF | 65 |
75 |
47 |
0 |
YV | 25 |
35 |
11 |
0 |
TA | 60 |
55 |
32 |
0 |
LPD Average ( |
32.7 (23.0) | 40.5 (21.6) | 15.0 (15.6) | 2.4 (3.7) |
12th graders | 3.0 (2.7) | 7.0 (7.6) | 4.2 (4.4) | 1.6 (1.7) |
7–8th graders | 3.0 (3.5) | 3.5 (5.3) | 2.6 (2.8) | 1.2 (2.3) |
5–6th graders | 0.5 (1.6) | 4.0 (5.2) | 1.1 (2.2) | 1 (3.3) |
Each of the individual participants showed this pattern of more errors on pseudowords that involved transposition next to an inflectional / derivational morpheme than on pseudowords derived by transpositions of exterior letters. This difference was significant or approached significance (
Thus, like in the oral reading Experiments (1 and 2), individual and group level analyses indicate that lexical decision is also vulnerable to migrations when the pseudoword is derived by transposing letters next to inflectional and derivational morphemes, whereas exterior transpositions are rare. This suggests that letters on the edge of the root, adjacent to an inflectional/derivational morpheme, are considered middle letters by the position encoding procedure.
To further test the effect of sentential context on migratability of letters near morphemes, we administered a lexical decision test using migratable words incorporated in sentences. Presenting the transposition errors within sentences allowed us to also include transpositions next to bound function morphemes, which we could not use in the single word lexical decision task.
A total of 64 sentences were presented to each participant: 8 sentences with a pseudoword that was formed by transposing the root letters near an inflectional morpheme (example 8); 7 sentences with a pseudoword formed by transposing the root letters near a derivational morpheme (example 9), and 15 sentences with a pseudoword formed by transposing the root letters near a bound function morpheme (example 10). The 9 control sentences included a pseudoword formed from a real word by the substitution of a single letter (example 11), and could not form any existing word following transposition. Twenty five length-matched sentences written correctly were presented as fillers.
The participants were requested to read each sentence silently and to judge whether the words in the sentence are written correctly or not.
(8) Migration near inflection:
Ɂo
Danny's mother pseudoword (works) in the kindergarten
(9) Migration near derivation:
h
I received pseudoword (an invitation) to my aunt's wedding
(10) Migration near a bound function morpheme:
b
He worked yesterday pseudoword (in the library)
(11) Letter substitution control:
ldSt (l
All people are invited pseudoword (to approach) the table
The lexical decision task in which the transposed pseudowords were incorporated into sentences yielded similar results to Experiments 1–3 (see Table
YO | 63 |
86 |
50 |
0 | 0 |
OR | 38 |
29 |
29 |
0 | 4 |
BR | 25 |
0 | 14 |
0 | 0 |
MR | 38 |
14 | 21 |
11 |
4 |
EL | 25 |
14 | 0 | 0 | 0 |
AD | 25 |
29 | 0 | 0 | 12 |
TL | 38 |
57 |
7 | 0 | 20 |
SK | 50 |
14 | 21 |
11 |
0 |
AF | 50 |
57 |
29 |
0 | 4 |
YV | 25 |
14 | 0 | 0 | 0 |
TA | 63 |
71 |
7 | 33 |
0 |
LPD Average ( |
39.8 (14.7) | 35.1 (28.1) | 16.2 (15.7) | 5.1 (10.3) | 4.0 (6.4) |
12th graders | 2.5 (5.3) | 2.9 (4.5) | 1.4 (3) | 0 (0) | 0.8 (1.7) |
7–8th graders | 1.3 (4.0) | 1.4 (4.5) | 0.7 (2.3) | 0 (0) | 0.4 (1.3) |
5–6th graders | 3.8 (8.4) | 7.1 (12.1) | 1.4 (3.0) | 0 (0) | 0.8 (1.7) |
At the individual participant level the pattern was similar, all but one participant performed more poorly on the inflectional and derivational conditions (combined) compared with the bound function morpheme condition, a difference that was significant for 3 of the participants. There were no differences between the inflectional and derivational conditions for any of the LPD participants.
Another task we used to examine whether the effect of different morphemes on migrations occurred also in silent reading was a comprehension task. Again, we tested word comprehension in a single word task (Experiment 5) and in words incorporated in sentences (Experiment 6).
We tested the comprehension of 60 migratable words using a word association task. Each migratable word was presented as part of a triad that included, in addition to the target migratable word, a pair of words, one was semantically related to the target word, the other was semantically related to a transposition error in the target word (examples 12–15). The participants were requested to choose the word that is semantically related to the target word, without reading the target word aloud. Again, the target migratable words in the test were of the four types: 15 words with potential of lexical transposition near an inflectional morpheme (12); 15 words with a potential of lexical transposition near a derivational morpheme (13); 15 words with a potential of lexical transposition error near a bound function morpheme (14), and 15 words with a potential of lexical transposition that involved exterior letters (15). In this task too, the inflectional, derivational, and exterior conditions included both words in which the transposition could occur on the left or adjacent to a relevant morpheme on the left of the word, and words in which the transposition was expected on the right. The target words of the various conditions did not differ in frequency [
(12) migration near inflection:
cables (dogs) - television / animals
(13) migration near derivation:
caught a fire (took a shower) – fire/bath
(14) migration near bound function morpheme:
the Negev, a southern Israeli desert zone (the thief) – sands / robber
(15) exterior migration:
rotten (near) – too ripe / not far
The performance of each participant in each condition is presented in Table
YO | 7 | 13 |
0 | 0 |
OR | 0 | 7 | 13 |
7 |
BR | 20 |
20 |
7 | 13 |
MR | 13 |
20 |
7 |
7 |
EL | 0 | 20 |
7 |
7 |
AD | 7 |
27 |
7 |
0 |
TL | 7 |
0 | 20 |
7 |
SK | 27 |
47 |
13 |
7 |
AF | 20 |
27 |
7 |
0 |
YV | 33 |
7 | 13 |
13 |
TA | 13 |
27 |
0 | 7 |
LPD Average ( |
13.4 (10.7) | 19.5 (12.9) | 8.5 (5.9) | 6.2 (4.6) |
12th graders | 1.3(3) | 2.7 (3.7) | 0 (0) | 0 (0) |
7–8th graders | 0 (0) | 2.7 (4.7) | 1.3 (4.2) | 0.7 (2.1) |
5–6th graders | 0 (0) | 3.3 (4.7) | 0 (0) | 0 (0) |
Each of the inflectional and derivational conditions separately yielded significantly poorer performance compared with exterior migration,
The last experiment tested comprehension of migratable words of the various morphological structures in a more natural task in which the migratable words were incorporated into sentences. The sentences were created in a way that both the target word and the result of the transposition error are plausible in the given sentential context. The participants were requested to read each sentence silently and then to paraphrase it. We assessed whether the paraphrase reflected the target word or its transposition.
The test included 30 sentences, each with a migratable word. We compared the performance on 15 sentences with a word in which the transposition occurred adjacent to an inflectional (10 sentences) or derivational (5 sentences) morpheme, see examples (16) and (17), with 15 sentences with a word in which the transposition occurred adjacent to a bound function morpheme (18). The different conditions did not differ in frequency [
(16) Migration near inflection:
After the grandpa died, there arrived to the family house many telegrams (visitors)
(17) Migration near derivation:
The tourist can also speak Arabic (Hebrew).
(18) Migration near a bound function morpheme:
I saw the policemen that-parked (that-rested) on the lawn.
Sentences whose paraphrases indicated that the participant read the target word incorrectly but with an irrelevant (non-migration) error type were excluded from the analysis (16 such sentences were removed in total).
The comprehension of the migratable words in sentences, summarized in Table
YO | 33 |
7 |
OR | 27 |
7 |
BR | 21 |
14 |
MR | 40 |
7 |
EL | 43 |
0 |
AD | 20 |
0 |
TL | 27 |
7 |
SK | 36 |
0 |
AF | 20 |
7 |
YV | 33 |
0 |
TA | 40 |
7 |
LPD Average ( |
30.9 (8.4) | 5.1 (4.5) |
12th graders | 4.0 (6.0) | 1.3 (3.0) |
7–8th graders | 5.3 (4.2) | 1.5 (2.9) |
5–6th graders | 4.0 (4.7) | 0.6 (2.0) |
The pattern that the LPD participants demonstrated was consistent across the six tasks: they made very few migrations adjacent to bound function morphemes, at a rate that was similar to the low rate of exterior letter migrations, indicating they treated letters adjacent to bound function morphemes practically as exterior letters. They made significantly more migrations adjacent to inflectional and derivational morphemes. Their error rates in the various conditions in the six experiments are summarized in Figure
One possible alternative explanation for the difference between letter position errors in words with bound function morphemes and words with inflectional/derivational morphemes is that bound function morphemes appear only word-initially, whereas inflectional/ derivational affixes appear both word initially and word finally (and sometimes even word-internally). However, when we compared only initial affixes, the differences between bound function affixes and inflectional/derivational affixes survived in each of the 4 experiments that included a bound function morpheme: there were significantly more transposition errors near initial inflection and derivation morphemes than near bound function morphemes, in Experiment 1,
Throughout Experiments 1–6, we had individuals with normal reading perform the same reading tasks as the LPD participants. They did not make many errors, but we were curious to see whether the few migration errors that occur in normal reading are affected by the morphological structure of the target word.
The participants we analyze in this section are 40 skilled readers, all Hebrew native speakers without any reading impairments according to the
Because this type of presentation yielded very few migrations in the control participants, we also added another group of 15 skilled readers, in more challenging reading conditions of limited exposure times of 300 and 100 ms. These 15 additional participants were 20–63 years old (
For the short exposure tests, the target words from Experiments 1, 3, and 5 were presented on a computer screen, for a limited time. The words for each of the three experiments (oral reading, lexical decision, comprehension) were presented in three separate blocks. Each participant saw the same 665 migratable words twice, a week apart, the words in each block were presented in a different order in the two sessions. Because most migratable words appeared in both orders in the word list (if SOFTIM appeared in the list, so did SOTFIM), and the words appeared in the list in a different order, there was no effect for remembering the words in the list. In the first session all words were presented for 300 ms (without masking). The second session, a week later, presented the same words, in a different order, for 100 ms.
In Experiment 1, the participants were requested to read each word aloud. In Experiment 3, they were requested to say, for each presented stimulus, whether it was an existing word. In Experiment 5, the participants were requested to explain each word in their own words.
The results of the individuals with normal reading, summarized in Table
12th graders | 1.2 (0.4) | 1.7 (2.0) | 0.3 (0.5) | 0.2 (0.2) |
7–8th graders | 0.9 (1.1) | 1.6 (1.5) | 0.2 (0.4) | 0.05 (0.1) |
5–6th graders | 1.1 (0.04) | 4.0 (2.3) | 0.3 (0.2) | 0.1 (0.3) |
Adults in 300 ms | 0.6 (0.9) | 2.2 (2.1) | 0.3 (0.6) | 0.2 (0.5) |
Adults in 100 ms | 1.9 (1.9) | 3.5 (3.5) | 0.8 (1.3) | 0.1 (0.3) |
12th graders | 3.0 (2.7) | 7.0 (7.6) | 4.2 (4.4) | |
7–8th graders | 3.0 (3.5) | 3.5 (5.3) | 2.6 (2.8) | |
5–6th graders | 0.5 (1.6) | 4.0 (5.2) | 1.1 (2.2) | |
Adults in 300 ms | 4.3(4.9) | 3.0 (3.7) | 1.4 (2.4) | |
Adults in 100 ms | 4.0 (6.2) | 7.0 (6.8) | 2.8 (3.4) | |
12th graders | 1.3(3) | 2.7 (3.7) | 0 (0) | 0 (0) |
7–8th graders | 0 (0) | 2.7 (4.7) | 1.3 (4.2) | 0.7 (2.1) |
5–6th graders | 0 (0) | 3.3 (4.7) | 0 (0) | 0 (0) |
Adults in 300 ms | 1.8 (5.3) | 3.6 (6.1) | 1.3 (2.8) | 0.4 (1.7) |
Adults in 100 ms | 6.2 (7.3) | 3.6 (4.3) | 2.7 (3.4) | 2.2 (5.4) |
12th graders | 2.5 (5.6) | 5.7 (7.8) | 2.9 (3.9) | |
7–8th graders | 7.5 (8.7) | 5.7 (7.4) | 0.7 (2.3) | |
5–6th graders | 3.8 (6.0) | 12.9 (8.1) | 1.4 (4.5) | |
12th graders | 2.5 (5.3) | 2.9 (4.5) | 1.4 (3) | |
7–8th graders | 1.3 (4.0) | 1.4 (4.5) | 0.7 (2.3) | |
5–6th graders | 3.8 (8.4) | 7.1 (12.1) | 1.4 (3.0) | |
12th graders | 2.0 (4.5) | 8.0 (11.0) | 1.3 (3.0) | |
7–8th graders | 4.4 (5.3) | 6.7 (10.0) | 1.5 (2.9) | |
5–6th graders | 2.7 (4.7) | 7.3 (10.1) | 0.6 (2.0) |
Not surprisingly, the condition that yielded most migrations was the shortest exposure time. In reading aloud, significantly more migrations occurred near inflection or derivation than near bound function morphemes,
In the longer exposure condition the pattern was similar: migrations occurred more often adjacent to inflectional and derivational morphemes than adjacent to bound function morphemes and exterior letters. These differences reached significance only in the comparisons between derivation and bound function morphemes,
In the lexical decision and comprehension tasks too, more migrations occurred in the letters near inflection and derivational morphemes than in letters near bound function morphemes and exterior letters, but most of these differences did not reach significance [the only significant difference was the one between the derivation and exterior conditions,
The unlimited presentation yielded even fewer migrations, but the same pattern persisted, although only few of the comparisons were significant, due to the ceiling effect. In
The pattern of migration errors in
The same tendency was found in
This study examined the nature of early morphological decomposition in reading via testing letter position errors that individuals with LPD make in words of various morphological structures. The study was based on the well-established finding that in LPD almost only middle letters migrate whereas exterior letters are less prone to errors. We used this fact to ask whether morphological decomposition occurs prior to letter position encoding: we reasoned that if words are decomposed to their roots and morphological affixes, then letters that used to be internal in the visually perceived complex word become exterior following decomposition (such as in the case of the English word
The assessment of the effect of morphology on letter position errors in LPD indicated that morphological decomposition follows letter position encoding for inflectional and derivational morphology. This makes sense: it is hard to imagine how morphological analysis of a morphologically complex word can proceed before the order of the letters is encoded (after all, -ment is a suffix, but -nemt is not). We reached this conclusion on the basis of the finding that letter position errors occurred in the root letters adjacent to inflectional and derivational affixes even when morphological decomposition would make these letters exterior and hence less liable to migrations. Namely, letter position errors occurred prior to the analysis of the inflection and derivation in morphologically complex words.
The results also clearly indicated that letter position errors are sensitive to the morphological structure of the target word: whereas the participants made migration errors on the letters that were adjacent to inflectional and derivational morphemes, treating them as middle letters, they did not make almost any migration errors on root-exterior letters that were adjacent to a bound function word (namely, when encountered with a letter string composed of a bound function morpheme and a word, parallel to
We suggest that these results can be explained if one distinguishes between morphological
This analysis is enough for morphologically complex words that include inflectional and derivational morphology to access the next stages of reading: the orthographic input lexicon and the sublexical route. Letter position encoding occurs prior to this morphological analysis and hence letter errors affect letters of the root even if they are adjacent to inflectional or derivational morphemes. We assume that in inflectional and derivational morphemes, the system encodes letter position for the whole complex word, and then during the morphological analysis, when the three letters of the root are extracted, they receive their letter position within the root directly as part of the analysis: if the word is
The story is different when this early morphological analysis detects that the letter string cannot be analyzed as including a root and inflectional and derivational morphemes, as is the case in words with bound function morphemes like
Of interest is also the finding that there were practically no transpositions across a function morpheme boundary: the letter of the function morpheme almost never transposed with the letters of the root, suggesting another corroboration for the conclusion that morphological decomposition of bound morphemes occurs prior to letter position encoding.
The results showing the morphological effects on letter position errors were consistent across the 6 experiments, on words presented in isolation and within sentences, and were evinced both in the reading of the participants with LPD and in the reading of the skilled readers, who made much fewer errors, but with the same patterns.
Our results also suggest some further insights as to the nature and locus in the reading process in which morphological analysis occurs: they suggest, like many previous studies, including studies on morphological analysis in peripheral dyslexias, that the morphological analysis does not rely on lexical considerations but rather on a structural analysis of the words.
This conclusion is supported by three findings in the current study: firstly, LPD is a deficit at the letter position encoding function in the early, pre-lexical stage of orthographic-visual analysis. The fact that morphological structure affects letter position errors, at least in the case of bound function morphemes, suggests that morphological analysis occurs in this early stage of orthographic-visual analysis.
Secondly, there were words that started with a bound function morpheme but could structurally be analyzed as starting with a verbal derivational affix, although the root does not exist with this derivational affix (see Appendix B). Such words were analyzed as starting with a derivational affix, as indicated by the higher rate of migrations adjacent to their first letter. The fact that the analysis created a non-existing word indicates that the analysis was structurally, rather than lexically driven (in line with previous studies such as Longtin et al.,
This conclusion of pre-lexical morphological analysis is also supported by the finding that nonwords showed exactly the same morphological effect as words: Experiments 3 and 4 showed that even in morphologically complex nonwords, in which both the whole nonword and its root did not exist, there were much fewer migration errors adjacent to a bound function morpheme than adjacent to inflectional and derivational morphemes
Such pre-lexical, structurally-based analysis takes place both when reading a whole sentences and when morphologically complex words are presented in isolation.
Given that 11 of the participants had developmental LPD, the results also shed light on the source of developmental LPD, and, more specifically, shed light on what cannot be the source of developmental LPD.
Firstly, as in many other cases of developmental LPD (Friedmann and Rahamim,
Furthermore, some studies ascribe developmental dyslexia to impaired morphology (Shu et al.,
Finally, and this applies to both developmental and acquired LPD, some accounts for letter migrations provide visually-based explanations for the relative immunity of exterior letters to letter migration. The current results suggest that this cannot be the whole story, because stem-exterior letters may be immune to migrations even when they visually appear word-interiorly. We saw that first letters of the root, when appearing right after a bound function morpheme, very rarely migrate, and their migration rate is comparable to that of first letters of the root that are also visually exterior. This suggests that morphological-orthographic processing also contribute to the relative immunity of exterior letters.
Therefore, the results of the current study show that developmental LPD does not stem from a phonological, lexical, morphological, or visual impairment. These results thus are also inconsistent with general claims that do not distinguish between different types of developmental dyslexia, which suggest that one of these factors is the source of developmental dyslexia in general.
The authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest.
This research was supported by the Israel Science Foundation (grant no. 1066/14), US-Israel Binational Science Foundation (BSF grant 2011314), and by the Australian Research Council Centre of Excellence for Cognition and its Disorders (CE110001021).
safarti
counted-past-1sg
safart, safarta
counted-past-2sg-fem counted-2sg-mas
safra, sifra
counted-past-3sg-fem, her book (also derivation: digit)
safarnu
counted-past-1pl
safartem
counted-past-2pl-mas
safarten
counted-past-2pl-fem
safru
count-past-3pl
espor
count-fut-1sg
tesapri, tisperi
cut-hair-fut-2sg-fem, tell-fut-2sg-fem, count-fut-2sg-fem
yispor
count-fut-3sg-mas
nispor
count-fut-1pl
tisperu, tesapru
count-fut-2pl, cut-hair-fut-2pl, tell-fut-2pl
yisperu, yesapru
count-fut-3pl, cut-hair-fut-3pl, tell-fut-3pl
sofer
counts-mas (also derivational: author-mas)
soferet
counts-fem (author-fem)
sofrim
count-pres-pl-mas (author-pl-mas)
sofrot
count-pres-pl-fem (author-pl-fem)
sfarim, saparim
books, barbers
sifri, sfarai, sapri
my-book, my books, tell-imperative-fem-sg
sifrex, sifrexa
your-fem-book, your-mas-book
safran
librarian-mas
sifriya
library
sifrut, sfarot, saparut
literature, digits, hairdressing
histaper
cut-hair-refl (got a haircut)
siper
told, cut-hair
nispar (nesaper)
was-counted (can also be inflection: tell-fut-1pl)
saparit (sifriyat)
hairdresser-fem (library-of)
sipur
story
siporet
fiction
mispar (mesaper)
number (can also be inflection: tells-3sg-mas)
misperet (mesaperet)
scissor-kick (can also be inflection: tells-3sg-fem)
sifron
booklet
mispara
barbershop
misparayim
scissors
histaparnu
we-got-a-haircut (cut-hair-refl-1pl)
sipartem
told-past-2pl, cut hair-past-2pl
nisperu
were-counted
mistaprot
getting-a-haircut-pres-pl-fem
misparim
numbers
safraniyot
librarian-fem-pl
hasefer
the-book
vesefer
and-book
shesafar
that-counted, that-a-book
lasefer, lesefer (lesaper)
to-the-book, to-a-book (also inflectional: to tell)
misefer (mispar)
From-a-book (also derivational: number)
basefer, besefer
in-a-book, in-the-book
kesefer
as-a-book
We saw that bound function morphemes behave differently from other morphemes in their effect on letter position errors. As a next step we asked whether it is the letter itself that is identified as a “function letter” by the morphological mechanisms in the orthographic-visual analyzer, or whether a first-pass analysis of the whole word is done. For this aim, we made two additional analyses that took advantage of the fact that some Hebrew letters can represent both bound function morphemes and inflectional or derivational morphemes, and some can be both bound function morphemes and root letters.
The letters
We examined the rate of transposition errors near the three ambiguous letters when they functioned as bound function morphemes, and compared them to words in which they functioned as inflectional or derivational morphemes. We also compared the rate of transpositions near these letters when they functioned as bound function morphemes compared to the rate of transpositions near non-ambiguous bound function morphemes (
This analysis revealed that when the first letter functioned as an inflectional or a derivational morpheme, and was part of a derivational/inflectional structure, the LPD participants made three times more transpositions (13.2%) near it than when it functioned as a bound function morpheme (4%), a difference that was significant, χ2 = 22.13,
All letters that are part of morphological affixes can also function as root letters. We analyzed the letters
We compared the rate of transposition errors near the two ambiguous letters when they functioned as bound function morphemes, and when they functioned as the first letter of the root. In this analysis we only included words in which a structural-morphological analysis can identify the role of the first letter: we therefore selected words with at least 4 letters in which the first letter was the ambiguous
For example,
The results, again, indicated that a full morphological analysis of the word is done, and not only identification of the first letter as one of a list of bound function morpheme letters. Twice as many migrations occurred in the (2nd and 3rd) letters that are adjacent to the ambiguous first letter when the first letter served as a root letter than when it served as a bound function morpheme. An average of 1.7 migrations occurred (for the 11 developmental LPD participants combined) when the first letter
This suggests that the morphological analysis takes into account the whole structure of the word, the existence of three consonant that could function as the root and the existence of other letters that can function as derivational or inflectional morphemes.
Finally, a further interesting finding relates to words that structurally could be analyzed as words (verbs) in a derivational template, but lexical knowledge actually indicates that this is a composition of a bound function morpheme and an existing word, whereas the derivational form is a non-word. (For example, the word with the bound determiner
These analyses indicate that the morphological parsing takes into account possible morphological templates and affixes, and analyzes the whole word. If three consonant letters are followed by letter(s) that are recognized to be a suffix, the first letter is analyzed as a root letter. If, however, a consonant letter that can be a bound function morpheme is followed by a morphological structure that includes three root letters in a known template, it is analyzed as a function morpheme, and hence is subject to decomposition and stripping off from the following word. Notice that such analysis can occur early, structurally, and without any access to the lexicon, but rather be based solely on knowledge of the existing templates and affixes, their position within the word, and the demand for three root consonant letters.
The differential information processing of derivationally complex word and a word with bound function word.
The Hebrew examples: a.
A parallel example in English would be the following, however, notice that it cannot reflect the whole story of Semitic languages like Hebrew, because there is no notion of the letters of the root and their order, neither is there a single letter that functions as a bound function prefix:
1Whereas letter identification and letter position encoding have to occur in the first stage of orthographic-visual analysis, letter-to-word binding may occur slightly later, in the graphemic input buffer, which holds the products of letter identification and position stages, a stage that can hold more than a single written word at a time.
2Most of these bound function morphemes have a full-word counterpart that appears as a stand-alone function word. Talmy Givón (
3In Hebrew, due to the under-specification of vowels in the orthography, and to the fact that there are 9 letters that have an ambiguous conversion to phonemes, 13 homophonic letters, and lexical stress that is not marked in the orthography, there are actually no regular words. Therefore, all words in the screening tests were irregular, but for the detection and identification of surface dyslexia, we used the two types of words that are most sensitive to surface dyslexia: potentiophones –words whose reading via grapheme-to-phoneme conversion creates another existing word, like
4As the screening test reading (Table
5We selected this exterior control condition because we were interested in whether the migrations adjacent to a morpheme behave like exterior migrations. A middle letter migration control condition, which involves migration of middle letters within the root and not adjacent to morphemes, is impossible in Hebrew because Hebrew words are based on 3-letter roots. Interior letter migrations require at least 4 letters, but 4 letter words inevitably include affixes. Therefore, middle letter control items that involve migration of two letters of the root and do not include affixes are impossible (or are limited to loan words that do not have the Semitic morphological structure).
6We could not compare these migrations to migrations in the middle of the root because Hebrew roots are generally 3-letter roots, so there is no way for a migration to involve two letters in the middle of the root, and hence every migration of middle letters is on the edge of a suffix.
7An important distinction, which might underlie the reason why words that appear with a bound function morpheme need to be decomposed and return for re-encoding of letter positions, is the distinction between words and roots. Whereas derivational and inflectional morphemes in Hebrew (and in Semitic languages in general) appear with a root, bound function morphemes appear with a word. This word, in turn, may be morphologically complex in itself. Morphological analysis of morphologically complex words that are composed of a root and inflectional and derivational affixes is enough to allow access to the lexicon, because the identification of the derivational template and inflections provides information about the slots of the three consonants of the root and their order. Such analysis is impossible when a morphologically complex word appears bound to a bound function word. In this case, it seems that to apply morphological analysis and identify letter positions within the root, the word needs to be decomposed and stripped off the bound morpheme, and then fed to the process again, for re-encoding of letter position, followed by the iteration of the morphological analysis stage.
8Interestingly, Taft and Nillsen (
9Whereas words like the-art in Hebrew appear orthographically as one word but can be decomposed structurally based on knowledge of morphology and without any contribution of lexical knowledge, word-word compounds that occur in some other languages may require a different treatment. In languages like German and Italian, compounds may be created from two or more words combined (Kirschfruchtfaft, tostapane, see a recent special issue on compounds, Semenza and Luzzatti,