Research in Developmental Disabilities 33 (2012) 1366–1379

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Research in Developmental Disabilities

Probing the perceptual and cognitive underpinnings of braille reading.An Estonian population study

Anneli Veispak a,*, Bart Boets b, Mairi Mannamaa c, Pol Ghesquiere a

a Parenting and Special Education Research Unit, Faculty of Psychology and Educational Sciences, University of Leuven, Leopold Vanderkelenstraat 32,

PO Box 3765, 3000 Leuven, Belgiumb Leuven Autism Research Consortium, Child and Adolescent Psychiatry, University of Leuven (KU Leuven), Herestraat 49, Box 7003, 3000 Leuven, Belgiumc Department of the Development and Rehabilitation Center of Children and Adolescents, Children’s Clinic of Tartu University Hospital, N. Lunini 6,

51014 Tartu, Estonia

A R T I C L E I N F O

Article history:

Received 1 February 2012

Accepted 6 March 2012

Available online

Keywords:

Braille reading

Print reading

Phonological processing

Auditory processing

Tactile spatial resolution

A B S T R A C T

Similar to many sighted children who struggle with learning to read, a proportion of blind

children have specific difficulties related to reading braille which cannot be easily

explained. A lot of research has been conducted to investigate the perceptual and cognitive

processes behind (impairments in) print reading. Very few studies, however, have aimed

for a deeper insight into the relevant perceptual and cognitive processes involved in braille

reading. In the present study we investigate the relations between reading achievement

and auditory, speech, phonological and tactile processing in a population of Estonian

braille reading children and youngsters and matched sighted print readers. Findings

revealed that the sequential nature of braille imposes constant decoding and effective

recruitment of phonological skills throughout the reading process. Sighted print readers,

on the other hand, seem to switch between the use of phonological and lexical processing

modes depending on the familiarity, length and structure of the word.

� 2012 Elsevier Ltd. All rights reserved.

1. Introduction

Many studies have investigated the visual, auditory and phonological processes involved in print reading. Very fewstudies, however, have aimed for a deeper insight into the relevant perceptual and cognitive processes involved in braillereading, a writing system where visual processing is substituted by tactile processing. As the braille reading system islinguistically identical to classical print reading, models and findings from print reading research can be used for testinghypotheses about braille reading (Millar, 1997). The findings on braille reading, conversely, can contribute to understandingthe process of reading in general.

Braille is a tactile writing system, where each character is represented by a combination of one to six raised dots (Fig. 1). Adot may be raised at any of the six positions to form 64 possible subsets. Braille characters can represent individual letters(uncontracted braille, alphabetic) or letter clusters, numbers and short words (contracted braille, logographic) (Pring, 1984).Different types and amounts of contractions, aimed at saving space and speeding up the reading process, are used in differentlanguages. In standard English braille, for example, there are 189 contractions and short-form words (Greaney & Reason,1999), whereas in Estonian braille no contractions are used at all.

* Corresponding author. Tel.: +32 16 32 61 73; fax: +32 16 32 59 33.

E-mail address: Anneli.Veispak@ppw.kuleuven.be (A. Veispak).

0891-4222/$ – see front matter � 2012 Elsevier Ltd. All rights reserved.

doi:10.1016/j.ridd.2012.03.009

[(Fig._1)TD$FIG]

Fig. 1. Braille alphabet where each character is represented by a sign that is formed using a combination of 1–6 raised dots.

A. Veispak et al. / Research in Developmental Disabilities 33 (2012) 1366–1379 1367

Differently from visual processing, which enables simultaneous and parallel perception of text, the tactile modality offersa successive input and imposes a sequential nature of reading (Pring, 1984). Since fingers must necessarily pass over all thecharacters on a line, it is believed to mirror the grapho-phonological reading strategy (character-by-character) which isprominent in young and inexperienced print readers (Nolan & Kederis, 1969). Nevertheless, the typical word superiorityeffect (i.e., words are read more accurately and faster than pseudowords) has also been reported in braille readers (Krueger,1982; Simon & Huertas, 1998). Hence, it is still unclear to what extent braille readers are purely decoding during reading orwhether they also develop larger perceptual ‘units’ with increased proficiency. The sequential nature of braille and the factthat most braille readers do not use the global shape of words to access word meaning (Millar, 1997) implies that blendedphonology is the main strategy for tactile reading. Therefore an effective engagement of various phonological processingskills is required throughout the reading process.

A classical division of phonological abilities discerns three interrelated but distinctive phonological dimensions:phonological awareness (PA), verbal short-term memory (VSTM) and lexical retrieval of phonological codes (as assessed byrapid automatic naming tasks; RAN) (e.g., Wagner & Torgesen, 1987). From print reading research it is known that PA ismainly associated with reading accuracy and pseudoword reading, whereas RAN shows a stronger relationship with readingspeed and orthographic pattern recognition (Boets et al., 2010; Savage & Frederickson, 2005; Verhagen, Aarnoutse, & vanLeeuwe, 2008). Languages with inconsistent orthographies, like English, usually show a prolonged and distinct influence ofPA on reading (for a review, see Share, 2008), whereas RAN is a more important predictor for reading in languages withtransparent orthography, such as German, Italian, Spanish, Dutch and Finnish (e.g., Landerl & Wimmer, 2008). In Finnish,where slowness in reading is considered to be a relevant marker of dyslexia (Leinonen et al., 2001), the association betweenPA and reading acquisition has shown to be only pertinent during the first few months starting formal reading instruction(Holopainen, Ahonen, & Lyytinen, 2001). It has also been suggested that typical adult readers in highly transparent languagesswitch between phonological and lexical processing modes, both between and within words depending on the familiarity,length and structure of the word (Cossu, Gugliotta & Marshall 1995; Leinonen et al., 2001). Since Estonian is a languagewhich is literally phonemic, representing a transitional form from an agglutinating language to a fusional one, largelydiffering from Finnish just in the number of cases (14 instead of 15) and inflections, we hypothesize that similar relationsbetween phonological processing and reading will be observable in the sighted Estonian speaking sample.

Only limited data about the role of phonological processing in braille reading are available (see Veispak & Ghesquiere,2010, for a review). A relation between PA and braille reading accuracy and comprehension has been demonstrated (Arter,1998; Gillon & Young, 2002; Greaney & Reason, 1999). It was found that blind children reading below their age level are alsodelayed in their ability to understand the sound structure of spoken language at the phonemic level. Some studies haveshown braille readers to perform equally well or better than their sighted peers on PA tasks (Gillon & Young, 2002; Greaney &Reason, 1999; Wakefield, Homewood, & Taylor, 2006), whereas others state the opposite (Dodd & Conn, 2000). The VSTM ofblind individuals has been shown to be better compared to their sighted peers, in both adults (Roder, Rosler, & Neville, 2001)and children (Hull & Mason, 1995). No studies relating VSTM to braille reading performance, though, were found. The sameapplies to lexical retrieval. It seems that RAN tasks have never been administered to braille readers before.

Most research studying braille readers or comparing blind and sighted readers has been conducted in English speakingsamples. In addition to the opaque orthography, standard English braille also contains contractions, which have beendemonstrated to interfere with the development of PA in blind children (Dodd & Conn, 2000). Hence, comparing blind andsighted readers in a highly transparent language, like Estonian (with 100% isomorphism between phonology andorthography), where no contractions are used, may be highly informative. In view of the sequential nature of the braillereading, we hypothesize to observe differential associations between reading and phonological processing measuresbetween braille versus print readers.

A. Veispak et al. / Research in Developmental Disabilities 33 (2012) 1366–13791368

Several studies investigating (impairments in) print reading have postulated that auditory temporal processing abilitieshave a crucial impact on the development of adequate phonological representations (e.g., Richardson, Thomson, Scott, &Goswami, 2004; Tallal, 1980). Individuals with severe reading and/or spelling impairments (i.e., developmental dyslexia)have been demonstrated to present problems processing short and rapidly presented acoustic stimuli (e.g., Farmer & Klein,1995; McArthur & Bishop, 2001), as well as impairments in processing slowly varying amplitude and frequency modulatedsignals (e.g., Goswami et al., 2002; Talcott & Witton, 2002), and performance on these tasks has been associated with readingacquisition in both normal and dyslexic readers. Both types of auditory processing problems have been hypothesized toaffect the accurate detection of the acoustical changes in speech, which might consequently disrupt the normal developmentof the phonological system and result in problems learning to read and spell (Boets et al., 2011).

Thus far, no studies have investigated the relation between auditory processing and braille reading. There is someevidence that congenitally blind individuals have better pitch and temporal order discrimination (Gougoux et al., 2004;Starlinger & Niemeyer, 1981), are faster in processing auditory linguistic stimuli (Roder, Rosler, & Neville, 2000) and performmore accurately on synthetic speech perception tasks (Papadopoulos, Argyropoulos, & Kouroupetroglou, 2008) compared totheir sighted peers. Neville and Bavelier (2001) have hypothesized that superior rapid auditory processing may account formany of these language processing enhancements in early-onset blindness. However, none of those studies has interpretedtheir data in relation to braille reading performance. Considering the postulated association between auditory processing,speech perception and the quality of phonological representations, and given the role of phonological processing in braillereading, it seems highly relevant to investigate the interaction between these aspects in braille reading.

A specific aspect pertaining to braille reading is tactile spatial acuity. The function of visual processing in print reading issubstituted by tactile processing in braille reading. The slow-adapting type I (SAI) fibre system, beginning with Merkel-cellmechanoreceptors in the glabrous skin, has been shown to be responsible for the recognition and processing of braillecharacters (Phillips, Johansson, & Johnson, 1990). Interestingly, the same type of fibre system has been demonstrated to bedefective in adult dyslexic readers (Grant, Zangaladze, Thiagarajan, & Sathian, 1999; Stoodley, Talcott, Carter, Witton, &Stein, 2000), a finding which was interpreted as corroborating evidence for a general magnocellular deficit in dyslexia. Thereis some evidence that poor braille readers experience problems with tactile perception (Arter, 1998; Greaney & Reason,1999), but it has not been specified how tactile sensitivity was measured and to what aspects of braille reading it was related.

Against the background of research showing that individual differences in print reading are related to individualdifferences in auditory processing, speech perception, phonological processing and perhaps even tactile processing, weinvestigated these same processing skills in a group of blind braille readers as compared to sighted print readers. Both groupdifferences in performance and differences in correlation patterns between the groups are investigated. Complementary tothe preponderance of research in English speaking samples, we studied individuals from Estonia, who have a language with ahighly transparent orthography.

2. Material and method

2.1. Participants

All Estonian braille readers (BR, n = 13, mean age = 14 years 3 months) attending regular schools or following regularcurricula in special schools participated in the study. They all had normal hearing and normal intelligence. Twelve of the BRwere blind from birth, one of them lost his vision at the age of four. Seven out of 13 BR still perceive light, whereas the othersix have no remaining rest vision. One of the BR was later excluded from the analysis because of the side effects caused by thetreatment of neuroblastoma. Based on age, sex and verbal intelligence of the BR, a matched control group of sighted printreaders (PR) was composed (n = 13, mean age = 13 years 7 months). Table 1 displays descriptive statistics for both groups.

2.2. Measures

2.2.1. Intelligence tests

Since at the time of data collection no Estonian adaption of the Wechsler intelligence scales existed, a translation of theFinnish adaptation of the WISC-III (Wechsler, 1991) and a translation of the English WAIS-III (Wechsler, 1998) were used.

Table 1

Characteristics of the participants.

Braille readers (n = 12) Print readers (n = 13)

M SD Range M SD Range t test

Sex (male: female) 4:8 5:8 t(22) = .47, p = .64

Age in months 171 39 114–234 163 41 113–235

Verbal intelligence

Similaritiesa 14 2 11–19 13 2 8–17 t(22) = 1.34, p = .19

Vocabularya 14 4 6–18 14 2 9–18 t(22) = .01, p = .99a Standard scores with population average M = 10 and SD = 3.

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Two verbal subtests, similarities and vocabulary, from either WISC-III or WAIS-III were administered depending on the age ofthe participant. The participants were tested by an experienced clinical psychologist.

2.2.2. Reading tests

Using the same theoretical framework and psychometrical criteria of reading tests in Dutch (Cleuren, Duchateau, Sips,Ghesquiere, & Van hamme, 2006) an Estonian version of a word reading and pseudoword reading test were created. Bothtests consist of 3 lists of (pseudo)words comprising 40 1-syllable, 40 2-syllable and 40 3–4 syllable items. The number ofcorrectly read words and the time per list were assessed. As in the Dutch version, the items were presented in columns for thePR. For the BR, the stimuli were presented in rows to reduce the effect of hand movement efficiency.

2.2.3. Phonological awareness tests

Based on existing tests in Dutch (De Smedt & Boets, 2010) an Estonian phoneme-deletion task and spoonerism task werecreated and presented with E-prime 1.0 software (Schneider, Eschman, & Zuccolotto, 2002). The stimuli were displayedmonaurally over calibrated TDH-39 headphones. Additionally to accuracy, reaction-times were measured by the REACSYS R-51 voice key.

In the phoneme-deletion task, the participant had to delete a particular phoneme from a pseudo-word (e.g., MALP without/L/). The task contains three blocks consisting of two practice and eight test items each. The first block involved the deletion ofthe second phoneme of a 1-syllable pseudo-word with onset cluster. The second block required the deletion of thepenultimate phoneme of a 1-syllable pseudo-word with offset cluster. In the last block, the middle phoneme of a 2-syllablepseudo-word had to be deleted. Timing initiated after the stimulus was presented and ended at the beginning of the responseof the participant.

In the spoonerism task, the participant was instructed to exchange the initial phonemes of two presented words to createtwo new pseudo-words (e.g., SILM-RIIV becomes VILM-SIIV). The task contains three blocks consisting of two practice andeight test items each. In the first block there are words with a single consonant onset. The second block contains words withconsonant cluster onset and in the third block pseudo-words with a single consonant onset were presented. Timing initiatedafter the stimulus was presented and ended at the beginning of the response of the participant.

2.2.4. Verbal short-term memory tests

In order to measure VSTM a digit span task and non-word repetition task were administered. The digit span task assesses theimmediate serial recall of spoken lists of digits between one and nine. Stimuli consisted of 27 sequences of numbers with alist length increasing from 2 to 9 digits, with 3 stimuli for each list length. The sequences were presented monaurally via a CDrecording. The score of the test comprised the number of correctly recalled sequences. The non-word repetition task is used asa pure measure of verbal short-term memory since the unfamiliar phonological sequences of pseudo-words are believed tolimit the use of long-term memory representations to support recall (Gathercole, Willis, Baddeley, & Emslie, 1994). Based onthe principle of the Children’s Test of Non-word Repetition (Gathercole et al., 1994) an Estonian version of the task wascreated, which consists of 36 pseudo-words that range from three to five syllables, each length having 12 trials. The pseudo-words, pronounced at a consistent rate, were digitally recorded. The participant was asked to repeat the pseudo-wordimmediately after its presentation. The score on the test equals the number of correctly recalled pseudo-words.

2.2.5. Lexical access tasks

To evaluate lexical access, two serial rapid automatic naming tasks, digits and letters (van den Bos, Zijlstra, & Spelberg,2002), were used. Each task involves the presentation of a card of 50 stimuli randomly arranged, with each stimulusappearing 10 times. For the PR stimuli were presented in a regular way, arranged in 5 columns of 10 items each. For the BRthe stimuli were presented in 2 rows of 25 items each. This arrangement minimizes the effect of hand movement efficiency.Digit naming comprises of the digits 2, 4, 5, 8, 9. Letter naming involves naming of the lowercase letters or braille charactersd, o, a, s, p. The participants were instructed to serially name the stimuli on the card as fast and accurately as possible.Subsequently, the time to completion was transformed to the number of correctly named symbols per second.

2.2.6. Speech perception test

Based on the existing Dutch words-in-noise perception test (Wouters, Damman, & Bosman, 1994) an equivalent words-in-noise perception task was created in Estonian language. The task consists of 7 lists of 11 monosyllabic words, which arepresented monaurally. Stimuli are played directly from a Dell Latitude E6500 portable computer using the software interfaceAPEX 3 (Francart, van Wieringen, & Wouters, 2008) and passed through an external RME Hammerfall DSP voice card in orderto control the level of presentation. Simultaneously with the stimuli a continuous stationary speech noise is presented at afixed level of 70 dB SPL to the same ear. Words are presented at �2, �5 and �8 dB SPL signal-to-noise ratio (SNR). Beforeadministration of the 6 test lists (2 lists per SNR), 1 practice list was presented at 0 dB SNR. The participant’s task was torepeat the words as accurately as possible, resulting in a percentage correct word score for every test list.

2.2.7. Test for auditory processing

Auditory processing was assessed with a frequency modulation (FM) detection test where the participants had to detect a2 Hz sinusoidal frequency modulation of a 1 kHz carrier tone with varying modulation depth. Threshold was defined as the

A. Veispak et al. / Research in Developmental Disabilities 33 (2012) 1366–13791370

minimum depth of frequency deviation required to detect the modulation. Threshold was estimated using a three-intervalforced-choice oddity paradigm embedded within an interactive computer game (Laneau, Boets, Moonen, van Wieringen, &Wouters, 2005). The average of two thresholds was used as an indicator of auditory sensitivity. Stimuli were presentedmonaurally over calibrated TDH-39 headphones using the integrated audio card from a laptop routed to an audiometer. Amore detailed description of the stimuli, procedure and equipment is described by Boets, Wouters, van Wieringen, andGhesquiere (2006).

2.2.8. Tactile spatial acuity test

In order to measure tactile spatial acuity, a grating orientation (GO) task (Johnson & Phillips, 1981) was administered inline with the standard method described by Van Boven, Hamilton, Kauffman, Keenan, and Pascual-Leone (2000). The GO taskcomprises a set of eight hemispherical domes with gratings cut into their surfaces, resulting in parallel bars and grooves ofequal widths at each dome (JVP Domes, Stoelting Co., Wood Dale, IL). The participant’s hand was placed in a supinatedposition immobilizing the finger by adhesive tape attached to the nail. Gratings were applied manually to the distal pads ofthe middle and index fingers of the dominant hand in PR and reading hand in BR. For each trial, the grating is applied to thesurface of the distal pad along or perpendicular to the long axis of the finger and held for about 1.5 seconds. Participants arerequired to identify the stimulus orientation verbally before the stimulus is removed. Blocks of 20 trials for each grating wereadministered. The testing is initiated with the largest groove width provided in the set (3.00 mm). Thereafter, gratings arepresented in a descending groove width order until performance approaches chance level (50% correct responses). The GOthreshold is determined by interpolating between groove widths spanning 75% correct responses. The PR were blindfolded.

3. Results

The speech-in-noise perception data of one sighted and one blind participant were discarded due to equipment failure.The finger sensitivity data of one blind participant is missing since he claimed to have difficulty reporting direction. Resultson reading time, PA reaction time and FM detection were log-transformed to obtain normal distributions. Data with repeatedmeasures were analysed using repeated measures mixed model analysis (MMA), which is highly robust for deviations ofnormality, even in small sample sizes (Verbeke & Lesaffre, 1997). Post hoc analyses were corrected for multiple comparisonsusing the Holm-Bonferroni method. Due to the small sample size and non-normal distribution of some variables,nonparametric Kruskal–Wallis tests were used to investigate group differences for all measures with a single data point.Relations between measures were investigated using Spearman partial correlations. Differences in correlation patternsbetween the groups are described. The use of other more sophisticated statistical methods to investigate the interactions isnot feasible due to small sample size and lack of power.

Reading and PA measures in the current study comprised both the accuracy and the speed of performance. Whileaccuracy scores might lack the necessary variability in languages with regular orthography (Ziegler et al., 2010), the speedmeasures have shown to be less subject to ceiling effects (Patel, Snowling, & de Jong, 2004). However, since accuracy andspeed of PA and reading appear to be unrelated in the group of BR, it is informative to include them both to the analysis.

3.1. Group comparisons

3.1.1. Reading measures

A repeated measures MMA on reading accuracy (Fig. 2) with group (BR versus PR) as between-subject variable, length(1, 2 and 3–4 syllables) and word type (words versus pseudo-words) as within-subject variables revealed significant maineffects of length (F(2,115) = 11.29, p< .0001) and word type (F(1,115) = 46.96, p< .0001), and a marginally significant effectfor group (F(1,23) = 4.26, p = .05). It also showed a significant group�word type� length three-way interaction(F(6,115) = 4.64, p = .0003) and a non-significant group�word type (F(1,115) = 1.68, p = .198) interaction. Post hoc analysisrevealed that both BR and PR read pseudowords less accurately than words. While length has no influence on word readingaccuracy in either group, there is a significant length effect on pseudoword reading accuracy in both groups.

A repeated measures MMA on reading speed (Fig. 3) with group (BR versus PR) as between-subject variable and length(1, 2 and 3–4 syllables) and word type (words versus pseudo-words) as within-subject variables revealed significant maineffects of group (F(1,23) = 81.51, p< .0001), word type (F(1,115) = 276.06, p< .0001) and length (F(2,115) = 292.57,p< .0001). It also showed significant group�word type (F(1,115) = 8.77, p = .0037) and group�word type� length(F(6,115) = 6.05, p< .0001) interactions. Post hoc analysis demonstrated that PR read significantly faster than BR, irrespectiveof word type and length, and that in both groups words are read faster than pseudo-words, and short (pseudo)words (i.e., 1and 2 syllables) are read faster than long (pseudo)words (i.e., 3–4 syllables). Post hoc analysis of the significant interactionsindicates that the effect of word length is significantly different between words and pseudowords in the PR group(F(2,60) = 13.5, p< .0001), whereas the same interaction is non-significant in the BR group (F(2,55) = .51, p = .602).

In order to evaluate how the interaction of reading accuracy and speed influence reading performance in general, acombined reading index (number of correctly read items per second) was calculated for each syllable length (Fig. 4). Arepeated measures MMA on this combined reading index with group (BR versus PR) as between-subject variable, length (1, 2and 3–4 syllables) and word type (words versus pseudo-words) as within-subject variables revealed significant main effectsof length (F(2,115) = 152.20, p< .0001), word type (F(1,115) = 209.83, p< .0001) and group (F(1,23) = 64.28, p< .0001).

[(Fig._2)TD$FIG]

Fig. 2. Reading accuracy.

[(Fig._3)TD$FIG]

Fig. 3. Reading speed.

A. Veispak et al. / Research in Developmental Disabilities 33 (2012) 1366–1379 1371

Additionally significant group�word type (F(1,115) = 48.96, p< .0001) and group�word type� length (F(6,115) = 6.10,p< .0001) interactions were revealed. Post hoc analysis showed that both BR and PR read more words correctly per secondcompared to pseudowords and that BR score significantly lower compared to PR in reading both words and pseudowords.Post hoc analysis of the interactions revealed that in the group of BR there is no significant word type� length interaction(F(2,55) = .85, p = .434) whereas in the group of PR the word type� length interaction (F(2,60) = 2.55, p = .087) is nearlysignificant.

3.1.2. Phonological processing measures

Results on the phonological measures are displayed in Table 2. Based on a series of principal component factor analyses inprevious research (Boets et al., 2010), we can assume that the phonological battery represents the well-known three-dimensional phonological structure and composite scores for PA, VSTM and RAN were calculated by averaging the z-scores ofthe constituent tests. To assist in the interpretation of the results, composite values were transformed to effect sizesrelatively to the mean and standard deviation of the PR group. For PA separate composite scores were computed for accuracyand reaction time.

[(Fig._4)TD$FIG]

Fig. 4. Combined reading measure.

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BR and PR did not differ significantly on the PA tasks. Although BR were slightly more accurate on spoonerism, theyreacted a bit slower than PR on phoneme deletion and spoonerism. Similarly, there were no significant differences betweenthe performance of the blind and the sighted on VSTM tasks. On the RAN tasks, however, BR were slower to name the items,but the difference was only significant for the RAN digit naming condition.

3.1.3. Speech, auditory and tactile processing

The results on the speech-in-noise perception test are depicted in Fig. 5. A repeated measures MMA with the proportioncorrectly perceived words as dependent variable, group as between-subject variable and SNR (�2, �5 and �8 dB SNR) aswithin-subject variable revealed a significant effect for SNR (F(2,42) = 178.45, p< .0001), but not for group (F(1,21) = 2.41,p = .136) nor for group� SNR interaction (F(2,42) = 2.34, p = .108). Even though the group� SNR interaction was notsignificant, the post hoc analysis indicated that the groups did not differ on �2 and �5 dB SNR, but BR did perceivesignificantly more words correctly than PR in the most difficult condition (�8 dB SNR). These results were also confirmed bynonparametric statistics (Table 2).

Table 2

Results of phonological, speech and auditory processing as well as finger sensitivity.

Variable Braille readers Print readers Kruskal–Wallis test

M SD M SD

Composite PA accuracy .17 .65 0 1 H(1) = .11 p = .74

Phoneme deletion (% correct) .83 .11 .83 .12 H(1) = .09 p = .76

Spoonerism (% correct) .75 .11 .68 .18 H(1) = .73 p = .39

Composite PA speed �.71 1.80 0 1 H(1) = 1.07 p = .30

Phoneme deletion (ms) 2102 1592 1605 895 H(1) = .36 p = .55

Spoonerism (ms) 3711 2899 2141 1351 H(1) = 2.49 p = .11

Composite VSTM .29 .97 0 1 H(1) = .85 p = .35

Nonword repetition 27.5 5.7 26.5 3.7 H(1) = .39 p = .53

Digit span 15.5 3.3 14.2 4.2 H(1) = .67 p = .41

Composite RAN �.96 .65 0 1 H(1) = 7.10 p = .008

Digits (items/sec) 1.93 .33 2.53 .48 H(1) = 7.85 p = .005

Letters (items/sec) 2.26 .39 2.63 .57 H(1) = 2.16 p = .14

Composite speech-in-noise perception .52 1.06 0 1 H(1) = 2.00 p = .16

SNR �2 (% correct) 70 12 70 9 H(1) = .03 p = .85

SNR �5 (% correct) 47. 14. 44 12 H(1) = .75 p = .38

SNR �8 (% correct) 26. 6 15 5 H(1) = 11.81 p = .0006

FM (Hz) 5.3 2.9 7.3 3.5 H(1) = 3.13 p = .08

Composite Finger .81 .24 0 1 H(1) = 9.98 p = .002

Index Finger sensitivity (mm) 1.10 .19 1.82 1.26 H(1) = 6.98 p = .008

Middle Finger sensitivity (mm) .97 .29 1.73 .72 H(1) = 7.78 p = .005

[(Fig._5)TD$FIG]

Fig. 5. Speech-in-noise perception.

A. Veispak et al. / Research in Developmental Disabilities 33 (2012) 1366–1379 1373

Even though the average FM detection threshold was considerably lower in the BR group, the difference with PR did notreach significance (Table 2). The results on the grating orientation task (tactile spatial acuity) showed that BR havesignificantly more sensitive fingers than PR.

3.2. Relations between reading ability, phonological, speech and auditory processing, and finger sensitivity in print and braille

readers

Spearman partial correlations were calculated between all the assessed abilities, while partialing out the effect of age andverbal intelligence. In addition to the composite scores used for the group comparisons, several composite reading scoreswere created to test hypotheses about the applied reading routes. From a theoretical perspective, different reading processesmay be mobilized for reading words versus pseudowords, and short versus long items. Therefore, the following (composite)reading scores were used in the analyses: (1) word reading accuracy (1, 2 and 3–4 syllables), (2) pseudoword readingaccuracy (1, 2 and 3–4 syllables), (3) short item reading accuracy (1 syllable words and pseudowords), (4) long item readingaccuracy (2 and 3–4 syllable words and pseudowords), (5) word reading speed (1, 2 and 3–4 syllables), (6) pseudowordreading speed (1, 2 and 3–4 syllables) (7) short item reading speed (1 syllable words and pseudo-words), (8) long itemreading speed (2 and 3–4 syllable words and pseudo-words). To obtain a positive definite correlation matrix the (composite)scores for reading speed, PA reaction time, FM and finger sensitivity were multiplied by�1; thus, a higher score on a measureindicates a better ability.

3.2.1. Relations between reading and phonological processing

The correlations (Table 3) between PA and reading measures were low in the group of PR, approaching significance onlybetween PA speed and pseudoword reading speed (r(13) = .56, p = .07). In the group of BR, on the other hand, there were

Table 3

Spearman partial correlations between reading and phonological processing measures while controlling for age and verbal intelligence.

Variable Braille readers Print readers

PA accuracy PA speed VSTM RAN PA accuracy PA speed VSTM RAN

Word reading accuracy .33 .45 .17 .12 .21 .02 .02 .28

Pseudoword reading accuracy .66* .24 .64* .58o .23 .31 .12 .15

Short item reading accuracy .58o .10 .42 .37 .15 .24 .18 .44

Long item reading accuracy .59o .35 .59o .20 .22 .04 .19 .05

Word reading speed .16 .74* .23 .81** .19 .17 .10 .61*

Pseudoword reading speed .10 .80** .12 .70* .38 .56o .37 .42

Short item reading speed .08 .81** .28 .81** .39 .38 .09 .77**

Long item reading speed .03 .75* .17 .77* .34 .46 .33 .49

Note: Braille readers (N = 12) Print readers (N = 13)o p< .10.

* p< .05.

** p< .01.

Table 4

Spearman partial correlations between reading, speech, auditory and tactile processing while controlling for age and verbal intelligence.

Variable Braille readers Print readers

Speech-in-noise

composite

FM

sensitivity

Finger

sensitivity

Speech-in-noise

composite

FM

sensitivity

Finger

sensitivity

Word reading accuracy .01 .13 .50 .22 .41 .14

Pseudoword reading accuracy .75* .01 .66o .59o .43 .16

Short item reading accuracy .31 .08 .72* .24 .13 .27

Long item reading accuracy .56o .12 .51 .37 .00 .07

Word reading speed .04 .02 .70* .66* .08 .47

Pseudoword reading speed .12 .14 .32 .68* .11 .52

Short item reading speed .07 .02 .48 .45 .39 .42

Long item reading speed .08 .08 .62o .82** .23 .39

Note.

Braille readers (N = 12), except for speech-in-noise composite and finger sensitivity (n = 11)

Print readers (N = 13), except for speech-in-noise composite (n = 12)o p< .10.

* p< .05.

** p< .01.

A. Veispak et al. / Research in Developmental Disabilities 33 (2012) 1366–13791374

significant correlations between all the reading speed measures and PA speed as well as between pseudoword readingaccuracy and PA accuracy. VSTM, which in the group of PR did not correlate substantially to any reading variable, wassignificantly correlated to pseudoword reading accuracy (r(12) = .64, p = .04) and showed a substantial relation with longitem reading accuracy (r(12) = .59, p = .07) in the group of BR. RAN, which in the PR group was significantly correlated withword (r(13) = .61, p = .04) and short item reading speed (r(13) = .77, p = .005), correlated significantly with all the readingspeed measures in the group of BR.

3.2.2. Relations between reading, speech and auditory processing, and finger sensitivity

The correlations (Table 4) between speech-in-noise perception and reading measures are quite different in the groups ofPR and BR. While in the PR group speech-in-noise perception correlates significantly with reading speed measures andapproaches significance with pseudoword reading accuracy (r(12) = .59, p = .07), in the group of BR a significant correlation isobservable only with pseudoword reading accuracy.

No significant correlations between FM sensitivity and reading measures were observed in either group.Finger sensitivity, which has no considerable relation to any of the reading variables in the PR group, is significantly

correlated to both reading accuracy and speed in the group of BR. Finger sensitivity seems to contribute to reading accuracyin case of short and unfamiliar words and to reading speed when words are longer but well known.

3.2.3. Relations between phonological, speech, and auditory processing

The correlations (Table 5) between phonological, speech and auditory processing reveal a different pattern for PR and BR.In the group of PR both PA accuracy and speed correlate significantly with VSTM and substantially but not significantly toeach other. There are no significant correlations between PA, RAN, speech-in-noise detection and FM sensitivity. In the groupof BR PA accuracy correlates significantly with speech-in-noise perception, and also substantially with RAN (r(12) = .52,p = .12) and FM sensitivity (r(12) = .55, p = .10). PA speed is substantially correlated with RAN. Differently from the PR group,

Table 5

Spearman partial correlations between phonological, speech and auditory processing measures while controlling for age and verbal intelligence.

Variable Braille readers Print readers

2 3 4 5 6 2 3 4 5 6

1. PA accuracy .01 .38 .52 .71* .55 .55o .60* .36 .09 .25

2. PA speed .09 .63o .13 .02 .79** .41 .22 .41

3. VSTM composite .45 .46 .09 .10 .33 .01

4. RAN composite .36 .18 .07 .31

5. Speech-in-noise composite .27 .06

6.FM sensitivity

Note.

Braille readers (N = 12), except for speech-in-noise composite (n = 11)

Print readers (N = 13), except for speech-in-noise composite (n = 12)o p< .10.

* p< .05.

** p< .01.

A. Veispak et al. / Research in Developmental Disabilities 33 (2012) 1366–1379 1375

PA accuracy and speed do not correlate with each other nor with VSTM in the group of BR. There are no relevant correlationseither between speech-in-noise perception, FM sensitivity and RAN.

3.3. Differences in correlation patterns between braille and print readers

Due to the small sample size there are no reliable statistical methods to investigate group differences in correlations.Hence, we have calculated a difference in Spearman partial correlation coefficients between the groups, by subtracting the r

value of the BR group from the r value of the PR group (rPR� rBR = rPR-BR) for all included variables. Therefore a negative rPR-BR

value indicates a higher correlation coefficient in the group of BR, whereas a positive rPR-BR value indicates a highercorrelation coefficient in the group of PR. Fishers r to z transformation test was used to assess the significance of thedifference between two correlation coefficients, where ra was always the coefficient of the PR group and rb the coefficient ofthe BR group. One-tailed test of significance was used and group differences in correlations were interpreted as substantialwhile adopting an a = .10. The results are displayed in Table 6.

3.3.1. Differences in correlations between reading and phonological processing measures

The correlations between the reading measures, when observing the rPR-BR values, are quite similar in both groups. Thereare, however, a couple of essential differences. Firstly, in the PR group pseudoword reading accuracy and speed aresignificantly correlated to each other (r(13) = .63, p = .04), whereas in the BR group they are not (r(12) = .08, p = .82). Thecomparison of the two correlation coefficients showed that the correlation between pseudoword reading accuracy and speedis considerably higher in the PR group (z = 1.44, p = .07). Secondly, the correlation between pseudoword reading accuracy andshort item reading accuracy is substantially higher in the BR group (z =�1.52, p = .06).

The rPR-BR values demonstrate that both PA accuracy and speed have a much stronger relation to reading performance inthe group of BR compared to the group of PR. Even though the rPR-BR values between PA accuracy and reading accuracymeasures are rather large, the difference in correlation coefficients did not turn out to be significant. However, thecorrelations between PA speed and word reading speed (z =�1.7, p = .04), as well as short item reading speed (z =�1.58,p = .05) are significantly higher in the group of BR compared to PR. The correlation between PA accuracy and speed, whichwas significant in the PR but not in the BR group, turned out to be considerably bigger (z = 1.32, p = .09) in the PR group.

The relation between VSTM and reading variables, as reflected by the rPR-BR values, seems to be more essential in thegroup of BR, where the correlation between VSTM and pseudoword reading accuracy is substantially bigger than the samecorrelation in the PR group (z =�1.39, p = .08). On the other hand, in the group of PR the correlation between VSTM and PAspeed is significantly higher (z = 2.14, p = 02) than in the group of BR.

The correlations between RAN, which is a tactile task for the BR, and reading speed are a bit but not substantially higher inthe BR group compared to PR. The largest though non-significant difference in RAN correlation coefficients between BR andPR is the correlation with pseudoword reading accuracy, which indicates that lexical retrieval is not only related to readingspeed in the BR group, but also to the accuracy of decoding.

3.3.2. Differences in correlations between reading, speech, auditory and tactile processing measures

As expected based on the partial correlations, speech-in-noise perception has a very different relation to readingperformance in the groups of BR and PR. The correlations between speech-in-noise perception and reading speed measuresturned out to be significantly greater in the group of PR: word reading speed (z = 1.55, p = .06), pseudoword readingspeed (z = 1.46, p = .07) and long item reading speed (z = 2.22, p = .01). In the group of BR however, the correlation between

Table 6

Differences in Spearman partial correlation coefficients between the groups (rPR� rBR = rPR-BR).

Variables 2 3 4 5 6. 7 8 9 10 11 12 13 14 15

1. PA accuracy .44o .22 .16 �.62o �.30 �.08 �.12 �.43 �.43 �.37 �.03 .28 .31 .31

2. PA speed .70* �.22 .09 .39 �.13 �.43 .07 .14 �.31 �.57* �.24 �.43o �.29

3. VSTM composite �.35 �.13 �.08 �.37 �.15 �.52o �.24 �.40 �.13 .25 �.19 .16

4. RAN composite �.29 .13 �.09 .16 �.43 .07 �.15 .20 �.28 �.04 �.28

5. Speech-in-noise composite �.21 .01 �.21 �.16 �.07 �.19 .62o .56o .38 .74*

6. FM sensitivity .21 .28 .42 .05 �.12 .06 �.03 .37 .15

7. Finger sensitivity �.36 �.50o �.45o �.44 �.23 .20 �.06 �.23

8. Word reading accuracy 0 0 �.01 0 0 0 0

9. Pseudoword reading accuracy �.47o �.23 �.18 .55o .04 .40

10. Short item reading accuracy �.17 �.25 .17 �.15 �.07

11. Long item reading accuracy .21 .12 .24 .41

12. Word reading speed �.14 �.09 �.16

13. Pseudoword reading speed �.19 .01

14. Short item reading speed �.19

15. Long item reading speedo p< .10.

* p< .05.

A. Veispak et al. / Research in Developmental Disabilities 33 (2012) 1366–13791376

speech-in-noise perception and PA accuracy is substantially bigger than the same correlation in the PR group (z =�1.64,p = .05). The FM sensitivity correlation coefficients did not differ significantly between the groups.

Finger sensitivity, which was significantly correlated with both reading accuracy and speed in the group of BR and non-significantly to reading speed in the group of PR, seems to have a unique relation to reading accuracy in the group of BR whenthe correlation coefficients are compared. The correlations between finger sensitivity and pseudoword reading accuracy(z =�1.33, p = .09) as well as short item reading accuracy (z =�1.33, p = .09) turned out to be substantially bigger in the groupof BR.

4. Discussion

The aim of the present study was to investigate the differential impact of cognitive and perceptual abilities on print versusbraille reading and to compare the performance of the two groups. The results showed, in line with previous research, that BRread slightly less accurately and slower compared to PR (Simon & Huertas, 1998), which is not surprising considering theincreased error rate and the lower resolution of tactile processing. However, the results also show that there is a difference inthe way word length and its familiarity influence reading accuracy and speed between the groups, with word length having alarger impact on the reading performance of the BR than of the PR. Word reading accuracy is constant in both groups withincreasing word length, whereas pseudoword reading accuracy drops more rapidly with increasing pseudoword length inthe group of BR compared to PR. Reading speed in the BR group increases with an increasing number of syllables at the samerate for both words and pseudowords. In the PR group on the other hand, only pseudoword reading speed is significantlyinfluenced by the length of the items. When looking at the combined measure of accuracy and speed (items per second), itbecomes apparent that the pattern of decrease in performance with increasing item length is the same for words andpseudowords in the BR group and different in the PR group. This could apply to the recruitment of different routes for readingwords and pseudowords in the PR group (i.e., lexical versus phonological route, respectively), whereas in the BR group thesame sequential phonological strategy is used for reading both.

In line with previous studies BR did not differ from PR in their performance on PA tasks (Gillon & Young, 2002; Greaney &Reason, 1999; Wakefield et al., 2006). PR were significantly faster compared to BR on the RAN task, in particular on the RANdigits. This finding is not surprising given the tactile nature of the task in the BR group and considering that braille letters arecomposed of only one cell whereas digits are composed of two braille cells. The relatively intact processing of RAN letters fitswith the finding that there are no significant differences in reading speed for print and braille when the characters arepresented one by one (Legge, Madison, & Mansfield, 1999). BR neither outperformed PR on VSTM tasks as could have beenexpected based on earlier studies (Hull & Mason, 1995; Roder et al., 2000).

Even though the performance of the groups did not differ substantially on the phonological processing measures, thereseems to be a fundamental difference in the way these phonological sub-skills interact in support of the reading process.Firstly, PA accuracy and speed, which are strongly correlated to each other in the PR group, show no relation to one another inthe group of BR. In other words, PR who are accurate on PA tasks, are most likely also fast in the process. BR, on the otherhand, are accurate irrespective of whether they are fast or not. Additionally, PA measures, which correlate significantly withreading accuracy and speed in the group of BR, show a marginal relation only to pseudoword reading speed in the group ofPR. Secondly, VSTM, in line with previous studies (McBride-Chang, 1996), seems to be a highly integrated phonologicalcomponent in the group of PR, while showing no noteworthy correlation to any reading measures. In the group of BRconversely, VSTM has a direct and strong influence on reading accuracy, while not being correlated to PA measures at all. Andthirdly, lexical retrieval speed (RAN), which stands separately from PA and correlates significantly with word and short itemreading speed in the PR group, is substantially related to PA speed, pseudoword reading accuracy and to reading speed in thegroup of BR, irrespective of whether the words are short or long, familiar or not.

These results imply that the perceptual unit in braille reading is significantly smaller compared to the size of theperceptual unit in print reading. Hence, the fact of how fast and accurately the lexical sound forms of the perceptual units areretrieved, determines the speed of phonological blending and consequently, amongst other factors, also the speed of readingbraille. Based on the correlation pattern it can be assumed that the size of the perceptual unit of an Estonian print reader isflexible due to simultaneous visual processing and highly regular conversion rules, ranging from syllables to words.Consequently reading is an easier task for the sighted since the pieces of the puzzle are bigger. The different size of theperceptual unit would also explain why VSTM shows such a strong correlation with pseudoword reading in the BR, but not inthe PR group. Thus, there is reason to believe that similar to Finnish (Leinonen et al., 2001), typical Estonian sighted readersuse the lexical route for rapid recognition of short and familiar words, whereas long as well as pseudowords are decoded. Incontrast it can be concluded that the sequential nature of braille does impose a constant decoding in the reading process. Thefact that words are read faster and more accurately than pseudowords is in line with previous research (Millar, 1997) andonly implies that BR benefit from semantic information as well as PR do.

The group of BR significantly outperformed the group of PR on a finger sensitivity (tactile spatial acuity) task, which is inline with previous research (Grant, Thiagarajan, & Sathian, 2000; Van Boven et al., 2000). Since the braille letter shapes areless distinctive than those in the Roman alphabet and misperceiving the position of one dot can lead to misidentification ofthe letter, the correct identification of the relative spatial position of the dots is critical for recognizing the character (Dodd &Conn, 2000). Hence tactile spatial acuity has an essential influence on braille reading accuracy. The results of the currentstudy demonstrate that in the BR group finger sensitivity contributes to the accuracy of reading short pseudowords and to

A. Veispak et al. / Research in Developmental Disabilities 33 (2012) 1366–1379 1377

reading speed when the words are longer, but still familiar. In other words, the impact of sufficiently sensitive fingers onreading accuracy becomes apparent when the words are short enough not to overload VSTM and when semantic informationcannot be used to aid comprehension. Along the same lines, when semantic information lubricates accuracy of reading,sensitive fingers assist the speed of the process. It also has to be taken into account that perception of braille is not only atactile process, but actually rather a haptic one, involving both tactile sensitivity and active exploring movements. The waybraille readers move their hands in reading and what kind of strategies they use, is reflected in their reading speed. Handmovements depend on factors as brain asymmetry, the relative sensitivity of each finger, and possibly the effect of anytraining received at an early stage of learning (Lorimer, 2002). However, since there is no good way to measure the handmovement efficiency, the impact has to be taken into account when interpreting the results.

BR did not outperform PR on speech perception and auditory processing as could have been assumed on the basis ofearlier studies (Gougoux et al., 2004; Papadopoulos et al., 2008). BR did, however, perceive more words correctly in the mostdifficult listening condition of the speech-in-noise task. Given that the hearing level of BR was not better compared to PR andthat their threshold on the auditory processing task was not significantly lower, the superior performance on�8 SNR cannotsimply be accounted for enhanced auditory processing. Yet, these results could indicate the presence of a more finely tunedfiltering system in blind individuals for picking up relevant acoustic cues in background noise.

Longitudinal studies have demonstrated that early impairments in auditory processing and speech perception predict laterreading impairments (Boets et al., 2011; Leppanen et al., 2010; Molfese, 2000). It has been suggested that accurate detection ofslower frequency changes is needed for discriminating speech sounds in order to develop precise phonological representations(Talcott et al., 1999). Previous research has also shown that the association of speech perception with PA mediates the relation ofspeech perception to word reading both in children (Boets et al., 2010, 2006; Boets, Wouters, van Wieringen, De Smedt, &Ghesquiere, 2008; McBride-Chang, 1996) and in adults (Watson & Miller, 1993). In the present study speech perception seemsto be related to reading performance in both groups. In the group of PR speech-in-noise perception correlates with readingspeed and to some extent also with pseudoword reading accuracy. In the group of BR there is a significant relation betweenspeech-in-noise perception and pseudoword reading accuracy as well as PA accuracy. In other words, those PR who performedwell on a speech-in-noise perception task also read fast both words and pseudowords. Whereas those BR who performed wellon a speech-in-noise perception task were concurrently accurate on PA tasks and also read pseudowords highly accurately. FMsensitivity, which is not significantly related to any reading measure nor to speech-in-noise perception in either group, has aconsiderable, though non-significant, correlation with PA accuracy in the group of BR and with PA speed in the group of PR.Taken together, it appears that even though FM sensitivity has no direct impact on speech perception, both of these variablesseem to relate separately to PA in the Estonian speaking sample. Even though earlier studies have reported statisticallysignificant correlations between FM sensitivity and reading in both reading-impaired (Witton, Stein, Stoodley, Rosner, &Talcott, 2002; Witton et al., 1998) and typically developing individuals (Talcott et al., 1999, 2000, 2002), we have failed to findsuch correlations. This could be due to a lack of power of the small sample size, but may also be due to the age of the participantsof the current study. It is hypothesized that the introduction of phonological instruction changes the largely spontaneous,unconscious perceptual-acoustic manner of speech processing and induces a new, more explicit, top–down approach of dealingwith speech sounds. Furthermore, Boets et al. (2011) have shown that from first grade onwards the more implicit auditory andspeech processes have been fully incorporated in the explicit phonological awareness skills and, accordingly, they no longerprovide an independent contribution to reading development.

Even though it is impossible to demonstrate any causality or directionality within the current data, we assume that theability to detect slow frequency changes in order to discriminate speech sounds has had a similar impact on the developmentof phonological representations both in blind and sighted readers. But, since the sequential nature of braille imposes aconstant recruitment of phonological processing skills and since the lower resolution of the tactile modality requires aconscious effort to keep up the reading accuracy, the correlations of auditory and speech processing appear significant withaccuracy measures in the BR group. Conversely, due to the simultaneous visual processing, the regular conversion rules ofthe language and the fluent switching between lexical and phonological processing in the PR group, not much conscious andcognitive effort has to be put into ‘‘getting it accurately’’ but rather into the speed of the process. Hence, also the correlationsbetween reading speed and auditory as well as speech processing measures in the PR group.

5. Concluding remarks

The current study demonstrates that Estonian print readers, similar to the Finnish (Leinonen et al., 2001), also seem toswitch between the use of phonological and lexical processing modes depending on the familiarity, length and structure ofthe word. The process of decoding however, is an easy task, which is completed effortlessly and accurately due to theregularity of the language and the visual input modality. The sequential nature of braille on the other hand, does imposeconstant decoding and the effective use of PA skills, even in a transparent language like Estonian. Also, even though it isbelieved that the absence of vision leads to compensation in more sensitive hearing and better memory, the results of thecurrent study did not confirm these assumption. Blind BR performed as well as sighted PR on auditory as well as phonologicalprocessing tasks, outperforming the sighted only on finger sensitivity. This is also understandable given that the sense oftouch for the blind is not merely used for reading but in addition for interpreting many other aspects of the world.

We acknowledge that the largest shortcoming of the study is the limited sample size, which puts restrictions on theusability, validity and interpretability of many elaborated statistical methods, which in ideal circumstances could have been

A. Veispak et al. / Research in Developmental Disabilities 33 (2012) 1366–13791378

used. However, we would like to emphasize that the current sample of the braille readers who participated in the study,actually comprises the whole population of normally gifted braille reading children and youngsters in Estonia. Hence, theonly opportunity to enlarge the sample would be moving on to other language groups.

Acknowledgements

Anneli Veispak is a junior research fellow of the Research Foundation Flanders. The research was financed by the fund forScientific Research Flanders. We are grateful to all children, their parents, teachers and schools that participated in this study.

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