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1.  Multimodal Alexia: Neuropsychological Mechanisms and Implications for Treatment 
Neuropsychologia  2011;49(13):3551-3562.
Letter-by-letter (LBL) reading is the phenomenon whereby individuals with acquired alexia decode words by sequential identification of component letters. In cases where letter recognition or letter naming is impaired, however, a LBL reading approach is obviated, resulting in a nearly complete inability to read, or global alexia. In some such cases, a treatment strategy wherein letter tracing is used to provide tactile and/or kinesthetic input has resulted in improved letter identification. In this study, a kinesthetic treatment approach was implemented with an individual who presented with severe alexia in the context of relatively preserved recognition of orally spelled words, and mildly impaired oral/written spelling. Eight weeks of kinesthetic treatment resulted in improved letter identification accuracy and oral reading of trained words; however, the participant remained unable to successfully decode untrained words. Further testing revealed that, in addition to the visual-verbal disconnection that resulted in impaired word reading and letter naming, her limited ability to derive benefit from the kinesthetic strategy was attributable to a disconnection that prevented access to letter names from kinesthetic input. We propose that this kinesthetic-verbal disconnection resulted from damage to the left parietal lobe and underlying white matter, a neuroanatomical feature that is not typically observed in patients with global alexia or classic LBL reading. This unfortunate combination of visual-verbal and kinesthetic-verbal disconnections demonstrated in this individual resulted in a persistent multimodal alexia syndrome that was resistant to behavioral treatment. To our knowledge, this is the first case in which the nature of this form of multimodal alexia has been fully characterized, and our findings provide guidance regarding the requisite cognitive skills and lesion profiles that are likely to be associated with a positive response to tactile/kinesthetic treatment.
PMCID: PMC3221964  PMID: 21952194
acquired alexia; letter-by-letter reading; pure alexia; global alexia; alexia with agraphia; kinesthetic treatment
2.  Letter-recognition and reading speed in peripheral vision benefit from perceptual learning 
Vision research  2004;44(7):695-709.
Visual-span profiles are plots of letter-recognition accuracy as a function of letter position left or right of the midline. Previously, we have shown that contraction of these profiles in peripheral vision can account for slow reading speed in peripheral vision. In this study, we asked two questions: (1) can we modify visual-span profiles through training on letter-recognition, and if so, (2) are these changes accompanied by changes in reading speed? Eighteen normally sighted observers were randomly assigned to one of three groups: training at 10° in the upper visual field, training at 10° in the lower visual field and a no-training control group. We compared observers’ characteristics of reading (maximum reading speed and critical print size) and visual-span profiles (peak amplitude and bits of information transmitted) before and after training, and at trained and untrained retinal locations (10° upper and lower visual fields). Reading speeds were measured for six print sizes at each retinal location, using the rapid serial visual presentation paradigm. Visual-span profiles were measured using a trigram letter-recognition task, for a letter size equivalent to 1.4 × the critical print size for reading. Training consisted of the repeated measurement of 20 visual-span profiles (over four consecutive days) in either the upper or lower visual field. We also tracked the changes in performance in a sub-group of observers for up to three months following training. We found that the visual-span profiles can be expanded (bits of information transmitted increased by 6 bits) through training with a letter-recognition task, and that there is an accompanying increase (41%) in the maximum reading speed. These improvements transferred, to a large extent, from the trained to an untrained retinal location, and were retained, to a large extent, for at least three months following training. Our results are consistent with the view that the visual span is a bottleneck on reading speed, but a bottleneck that can be increased with practice.
PMCID: PMC2729075  PMID: 14751554
Reading; Letter-recognition; Peripheral vision; Perceptual learning; Low vision; Visual rehabilitation
3.  Dependence of Reading Speed on Letter Spacing in Central Vision Loss 
Crowding, the difficulty in recognizing a letter in close proximity with other letters, has been suggested as an explanation for slow reading in people with central vision loss. The goals of this study were (1) to examine whether increased letter spacing in words, which presumably reduces crowding among letters, would benefit reading for people with central vision loss; and (2) to relate our finding to the current account of faulty feature integration of crowding.
Fourteen observers with central vision loss read aloud single sentences, one word at a time, using rapid serial visual presentation (RSVP). Reading speeds were calculated based on the RSVP exposure durations yielding 80% accuracy. Letters were rendered in Courier, a fixed-width font. Observers were tested at 1.4× the critical print size (CPS), three were also tested at 0.8× CPS. Reading speed was measured for five center-to-center letter spacings (range: 0.5–2× the standard spacing). The preferred retinal locus (PRL) for fixation was determined for nine of the observers, from which we calculated the horizontal dimension of the integration field for crowding.
All observers showed increased reading speed with letter spacing for small spacings, until an optimal spacing, beyond which reading speed either showed a plateau, or dropped as letter spacing further increased. The optimal spacing averaged 0.95±0.06× [±95%CI] the standard spacing for 1.4× CPS (similar for 0.8× CPS), which was not different from the standard. When converted to angular size, the measured values of the optimal letter spacing for reading show a good relationship with the calculated horizontal dimension of the integration field.
Increased letter spacing beyond the standard size, which presumably reduces crowding among letters in text, does not improve reading speed for people with central vision loss. The optimal letter spacing for reading can be predicted based on the PRL.
PMCID: PMC3429790  PMID: 22842309
reading; crowding; central vision loss; low vision; age-related macular degeneration
4.  Accurate Reading with Sequential Presentation of Single Letters 
Rapid, accurate reading is possible when isolated, single words from a sentence are sequentially presented at a fixed spatial location. We investigated if reading of words and sentences is possible when single letters are rapidly presented at the fovea under user-controlled or automatically controlled rates. When tested with complete sentences, trained participants achieved reading rates of over 60 wpm and accuracies of over 90% with the single letter reading (SLR) method and naive participants achieved average reading rates over 30 wpm with greater than 90% accuracy. Accuracy declined as individual letters were presented for shorter periods of time, even when the overall reading rate was maintained by increasing the duration of spaces between words. Words in the lexicon that occur more frequently were identified with higher accuracy and more quickly, demonstrating that trained participants have lexical access. In combination, our data strongly suggest that comprehension is possible and that SLR is a practicable form of reading under conditions in which normal scanning of text is not possible, or for scenarios with limited spatial and temporal resolution such as patients with low vision or prostheses.
PMCID: PMC3483628  PMID: 23115548
visual prosthesis; bionic vision; low vision; reading; RSVP; phosphene; word recognition
5.  Learning to Identify Crowded Letters: Does It Improve Reading Speed? 
Vision research  2007;47(25):3150-3159.
Crowding, the difficulty in identifying a letter embedded in other letters, has been suggested as an explanation for slow reading in peripheral vision. In this study, we asked whether crowding in peripheral vision can be reduced through training on identifying crowded letters, and if so, whether these changes will lead to improved peripheral reading speed. We measured the spatial extent of crowding, and reading speeds for a range of print sizes at 10° inferior visual field before and after training. Following training, averaged letter identification performance improved by 88% at the trained (the closest) letter separation. The improvement transferred to other untrained separations such that the spatial extent of crowding decreased by 38%. However, averaged maximum reading speed improved by a mere 7.2%. These findings demonstrated that crowding in peripheral vision could be reduced through training. Unfortunately, the reduction in the crowding effect did not lead to improved peripheral reading speed.
PMCID: PMC2134936  PMID: 17928026
crowding; perceptual learning; training; reading
6.  Reading Speed, Comprehension and Eye Movements While Reading Japanese Novels: Evidence from Untrained Readers and Cases of Speed-Reading Trainees 
PLoS ONE  2012;7(5):e36091.
A growing body of evidence suggests that meditative training enhances perception and cognition. In Japan, the Park-Sasaki method of speed-reading involves organized visual training while forming both a relaxed and concentrated state of mind, as in meditation. The present study examined relationships between reading speed, sentence comprehension, and eye movements while reading short Japanese novels. In addition to normal untrained readers, three middle-level trainees and one high-level expert on this method were included for the two case studies.
Methodology/Principal Findings
In Study 1, three of 17 participants were middle-level trainees on the speed-reading method. Immediately after reading each story once on a computer monitor, participants answered true or false questions regarding the content of the novel. Eye movements while reading were recorded using an eye-tracking system. Results revealed higher reading speed and lower comprehension scores in the trainees than in the untrained participants. Furthermore, eye-tracking data by untrained participants revealed multiple correlations between reading speed, accuracy and eye-movement measures, with faster readers showing shorter fixation durations and larger saccades in X than slower readers. In Study 2, participants included a high-level expert and 14 untrained students. The expert showed higher reading speed and statistically comparable, although numerically lower, comprehension scores compared with the untrained participants. During test sessions this expert moved her eyes along a nearly straight horizontal line as a first pass, without moving her eyes over the whole sentence display as did the untrained students.
In addition to revealing correlations between speed, comprehension and eye movements in reading Japanese contemporary novels by untrained readers, we describe cases of speed-reading trainees regarding relationships between these variables. The trainees overall tended to show poor performance influenced by the speed-accuracy trade-off, although this trade-off may be reduced in the case of at least one high-level expert.
PMCID: PMC3348914  PMID: 22590519
7.  Improving word reading speed: individual differences interact with a training focus on successes or failures 
Reading and Writing  2011;25(9):2061-2089.
The effect of two training procedures on the development of reading speed in poor readers is examined. One training concentrates on the words the children read correctly (successes), the other on the words they read incorrectly (failures). Children were either informed or not informed about the training focus. A randomized controlled trial was conducted with 79 poor readers. They repeatedly read regularly spelled Dutch consonant–vowel–consonant words, some children their successes, others their failures. The training used a computerized flashcards format. The exposure duration of the words was varied to maintain an accuracy rate at a constant level. Reading speed improved and transferred to untrained, orthographically more complex words. These transfer effects were characterized by an Aptitude-Treatment Interaction. Poor readers with a low initial reading level improved most in the training focused on successes. For poor readers with a high initial reading level, however, it appeared to be more profitable to practice with their failures. Informing students about the focus of the training positively affected training: The exposure duration needed for children informed about the focus of the training decreased more than for children who were not informed. This study suggests that neither of the two interventions is superior to the other in general. Rather, the improvement of general reading speed in a transparent orthography is closely related to both the children’s initial reading level and the type of words they practice with: common and familiar words when training their successes and uncommon and less familiar words with training their failures.
PMCID: PMC3443357  PMID: 23002327
Training; Intervention; Orthography; Poor readers; Reading speed
8.  The Effect of Letter-stroke Boldness on Reading Speed in Central and Peripheral Vision 
Vision research  2013;84:33-42.
People with central vision loss often prefer boldface print over normal print for reading. However, little is known about how reading speed is influenced by the letter-stroke boldness of font. In this study, we examined the reliance of reading speed on stroke boldness, and determined whether this reliance differs between the normal central and peripheral vision. Reading speed was measured using the rapid serial visual presentation paradigm, where observers with normal vision read aloud short single sentences presented on a computer monitor, one word at a time. Text was rendered in Courier at six levels of boldness, defined as the stroke-width normalized to that of the standard Courier font: 0.27, 0.72, 1, 1.48, 1.89 and 3.04× the standard. Testings were conducted at the fovea and 10° in the inferior visual field. Print sizes used were 0.8× and 1.4× the critical print size (smallest print size that can be read at the maximum reading speed). At the fovea, reading speed was invariant for the middle four levels of boldness, but dropped by 23.3% for the least and the most bold text. At 10° eccentricity, reading speed was virtually the same for all boldness <1, but showed a poorer tolerance to bolder text, dropping by 21.5% for 1.89x boldness and 51% for the most bold (3.04x) text. These results could not be accounted for by the changes in print size or the RMS contrast of text associated with changes in stroke boldness. Our results suggest that contrary to the popular belief, reading speed does not benefit from bold text in the normal fovea and periphery. Excessive increase in stroke boldness may even impair reading speed, especially in the periphery.
PMCID: PMC3642228  PMID: 23523572
Reading; stroke boldness; peripheral vision
9.  Massive cortical reorganization in sighted Braille readers 
eLife  null;5:e10762.
The brain is capable of large-scale reorganization in blindness or after massive injury. Such reorganization crosses the division into separate sensory cortices (visual, somatosensory...). As its result, the visual cortex of the blind becomes active during tactile Braille reading. Although the possibility of such reorganization in the normal, adult brain has been raised, definitive evidence has been lacking. Here, we demonstrate such extensive reorganization in normal, sighted adults who learned Braille while their brain activity was investigated with fMRI and transcranial magnetic stimulation (TMS). Subjects showed enhanced activity for tactile reading in the visual cortex, including the visual word form area (VWFA) that was modulated by their Braille reading speed and strengthened resting-state connectivity between visual and somatosensory cortices. Moreover, TMS disruption of VWFA activity decreased their tactile reading accuracy. Our results indicate that large-scale reorganization is a viable mechanism recruited when learning complex skills.
eLife digest
According to most textbooks, our brain is divided into separate areas that are dedicated to specific senses. We have a visual cortex for vision, a tactile cortex for touch, and so on. However, researchers suspect that this division might not be as fixed as the textbooks say. For example, blind people can switch their 'leftover' visual cortex to non-visual purposes, such as reading Braille – a tactile alphabet.
Can this switch in functional organization also happen in healthy people with normal vision? To investigate this, Siuda-Krzywicka, Bola et al. taught a group of healthy, sighted people to read Braille by touch, and monitored the changes in brain activity that this caused using a technique called functional magnetic resonance imaging. According to textbooks, tactile reading should engage the tactile cortex. Yet, the experiment revealed that the brain activity critical for reading Braille by touch did not occur in the volunteers’ tactile cortex, but in their visual cortex.
Further experiments used a technique called transcranial magnetic stimulation to suppress the activity of the visual cortex of the volunteers. This impaired their ability to read Braille by touch. This is a clear-cut proof that sighted adults can re-program their visual cortex for non-visual, tactile purposes.
These results show that intensive training in a complex task can overcome the sensory division-of-labor of our brain. This indicates that our brain is much more flexible than previously thought, and that such flexibility might occur when we learn everyday, complex skills such as driving a car or playing a musical instrument.
The next question that follows from this work is: what enables the brain’s activity to change after learning to read Braille? To understand this, Siuda-Krzywicka, Bola et al. are currently exploring how the physical structure of the brain changes as a result of a person acquiring the ability to read Braille by touch.
PMCID: PMC4805536  PMID: 26976813
visual system; somatosensory system; fMRI; Human
10.  Learning to Identify Near-Acuity Letters, either with or without Flankers, Results in Improved Letter Size and Spacing Limits in Adults with Amblyopia 
PLoS ONE  2012;7(4):e35829.
Amblyopia is a developmental abnormality that results in deficits for a wide range of visual tasks, most notably, the reduced ability to see fine details, the loss in contrast sensitivity especially for small objects and the difficulty in seeing objects in clutter (crowding). The primary goal of this study was to evaluate whether crowding can be ameliorated in adults with amblyopia through perceptual learning using a flanked letter identification task that was designed to reduce crowding, and if so, whether the improvements transfer to untrained visual functions: visual acuity, contrast sensitivity and the size of visual span (the amount of information obtained in one fixation). To evaluate whether the improvements following this training task were specific to training with flankers, we also trained another group of adult observers with amblyopia using a single letter identification task that was designed to improve letter contrast sensitivity, not crowding. Following 10,000 trials of training, both groups of observers showed improvements in the respective training task. The improvements generalized to improved visual acuity, letter contrast sensitivity, size of the visual span, and reduced crowding. The magnitude of the improvement for each of these measurements was similar in the two training groups. Perceptual learning regimens aimed at reducing crowding or improving letter contrast sensitivity are both effective in improving visual acuity, contrast sensitivity for near-acuity objects and reducing the crowding effect, and could be useful as a clinical treatment for amblyopia.
PMCID: PMC3340394  PMID: 22558234
11.  Word-Initial Letters Influence Fixation Durations during Fluent Reading 
The present study examined how word-initial letters influence lexical access during reading. Eye movements were monitored as participants read sentences containing target words. Three factors were independently manipulated. First, target words had either high or low constraining word-initial letter sequences (e.g., dwarf or clown, respectively). Second, targets were either high or low in frequency of occurrence (e.g., train or stain, respectively). Third, targets were embedded in either biasing or neutral contexts (i.e., targets were high or low in their predictability). This 2 (constraint) × 2 (frequency) × 2 (context) design allowed us to examine the conditions under which a word’s initial letter sequence could facilitate processing. Analyses of fixation duration data revealed significant main effects of constraint, frequency, and context. Moreover, in measures taken to reflect “early” lexical processing (i.e., first and single fixation duration), there was a significant interaction between constraint and context. The overall pattern of findings suggests lexical access is facilitated by highly constraining word-initial letters. Results are discussed in comparison to recent studies of lexical features involved in word recognition during reading.
PMCID: PMC3317262  PMID: 22485100
reading; eye movements; word-initial letter constraint; word frequency; contextual predictability
12.  A Randomized Controlled Trial on The Beneficial Effects of Training Letter-Speech Sound Integration on Reading Fluency in Children with Dyslexia 
PLoS ONE  2015;10(12):e0143914.
A recent account of dyslexia assumes that a failure to develop automated letter-speech sound integration might be responsible for the observed lack of reading fluency. This study uses a pre-test-training-post-test design to evaluate the effects of a training program based on letter-speech sound associations with a special focus on gains in reading fluency. A sample of 44 children with dyslexia and 23 typical readers, aged 8 to 9, was recruited. Children with dyslexia were randomly allocated to either the training program group (n = 23) or a waiting-list control group (n = 21). The training intensively focused on letter-speech sound mapping and consisted of 34 individual sessions of 45 minutes over a five month period. The children with dyslexia showed substantial reading gains for the main word reading and spelling measures after training, improving at a faster rate than typical readers and waiting-list controls. The results are interpreted within the conceptual framework assuming a multisensory integration deficit as the most proximal cause of dysfluent reading in dyslexia.
Trial Registration: ISRCTN register ISRCTN12783279
PMCID: PMC4667884  PMID: 26629707
13.  Braille in the Sighted: Teaching Tactile Reading to Sighted Adults 
PLoS ONE  2016;11(5):e0155394.
Blind people are known to have superior perceptual abilities in their remaining senses. Several studies suggest that these enhancements are dependent on the specific experience of blind individuals, who use those remaining senses more than sighted subjects. In line with this view, sighted subjects, when trained, are able to significantly progress in relatively simple tactile tasks. However, the case of complex tactile tasks is less obvious, as some studies suggest that visual deprivation itself could confer large advantages in learning them. It remains unclear to what extent those complex skills, such as braille reading, can be learnt by sighted subjects. Here we enrolled twenty-nine sighted adults, mostly braille teachers and educators, in a 9-month braille reading course. At the beginning of the course, all subjects were naive in tactile braille reading. After the course, almost all were able to read whole braille words at a mean speed of 6 words-per-minute. Subjects with low tactile acuity did not differ significantly in braille reading speed from the rest of the group, indicating that low tactile acuity is not a limiting factor for learning braille, at least at this early stage of learning. Our study shows that most sighted adults can learn whole-word braille reading, given the right method and a considerable amount of motivation. The adult sensorimotor system can thus adapt, to some level, to very complex tactile tasks without visual deprivation. The pace of learning in our group was comparable to congenitally and early blind children learning braille in primary school, which suggests that the blind’s mastery of complex tactile tasks can, to a large extent, be explained by experience-dependent mechanisms.
PMCID: PMC4871356  PMID: 27187496
14.  Effect of letter spacing on visual span and reading speed 
Journal of vision  2007;7(2):2.1-210.
S. T. L. Chung (2002) has shown that rapid serial visual presentation (RSVP) reading speed varies with letter spacing, peaking near the standard letter spacing for text and decreasing for both smaller and larger spacings. In this study, we tested the hypothesis that the dependence of reading speed on letter spacing is mediated by the size of the visual span—the number of letters recognized with high accuracy without moving the eyes. If so, the size of the visual span and reading speed should show a similar dependence on letter spacing. We tested this prediction for RSVP reading and asked whether it generalizes to the reading of blocks of text requiring eye movements. We measured visual-span profiles and reading speeds as a function of letter spacing. Visual-span profiles, measured with trigrams (strings of three random letters), are plots of letter-recognition accuracy as a function of letter position left or right of fixation. Size of the visual span was quantified by a measure of the area under the visual-span profile. Reading performance was measured using two presentation methods: RSVP and flashcard (a short block of text on four lines). We found that the size of the visual span and the reading speeds measured by the two presentation methods showed a qualitatively similar dependence on letter spacing and that they were highly correlated. These results are consistent with the view that the size of the visual span is a primary visual factor that limits reading speed.
PMCID: PMC2729067  PMID: 18217817
visual span; reading speed; letter spacing; visual crowding
15.  Crossmodal deficit in dyslexic children: practice affects the neural timing of letter-speech sound integration 
A failure to build solid letter-speech sound associations may contribute to reading impairments in developmental dyslexia. Whether this reduced neural integration of letters and speech sounds changes over time within individual children and how this relates to behavioral gains in reading skills remains unknown. In this research, we examined changes in event-related potential (ERP) measures of letter-speech sound integration over a 6-month period during which 9-year-old dyslexic readers (n = 17) followed a training in letter-speech sound coupling next to their regular reading curriculum. We presented the Dutch spoken vowels /a/ and /o/ as standard and deviant stimuli in one auditory and two audiovisual oddball conditions. In one audiovisual condition (AV0), the letter “a” was presented simultaneously with the vowels, while in the other (AV200) it was preceding vowel onset for 200 ms. Prior to the training (T1), dyslexic readers showed the expected pattern of typical auditory mismatch responses, together with the absence of letter-speech sound effects in a late negativity (LN) window. After the training (T2), our results showed earlier (and enhanced) crossmodal effects in the LN window. Most interestingly, earlier LN latency at T2 was significantly related to higher behavioral accuracy in letter-speech sound coupling. On a more general level, the timing of the earlier mismatch negativity (MMN) in the simultaneous condition (AV0) measured at T1, significantly related to reading fluency at both T1 and T2 as well as with reading gains. Our findings suggest that the reduced neural integration of letters and speech sounds in dyslexic children may show moderate improvement with reading instruction and training and that behavioral improvements relate especially to individual differences in the timing of this neural integration.
PMCID: PMC4478392  PMID: 26157382
developmental dyslexia; cross-modal integration; mismatch negativity; ERP; training effects
16.  Repetition priming in oral text reading: a therapeutic strategy for phonologic text alexia 
Aphasiology  2009;23(6):659-675.
Phonologic text alexia (PhTA) is a reading disorder in which reading of pseudowords is impaired, but reading of real words is impaired only when reading text. Oral reading accuracy remains well preserved when words are presented individually, but when presented in text the part-of-speech effect that is often seen in phonologic alexia (PhA) emerges.
To determine whether repetition priming could strengthen and/or maintain the activation of words during text reading.
Methods & Procedures
We trained NYR, a patient with PhTA, to use a strategy, Sentence Building, designed to improve accuracy of reading words in text. The strategy required NYR to first read the initial word, and then build up the sentence by adding on sequential words, in a step-wise manner, utilizing the benefits of repetition priming to enhance accuracy.
Outcomes & Results
When using the strategy, NYR displayed improved accuracy not only for sentences she practiced using the strategy, but unpracticed sentences as well. Additionally, NYR performed better on a test of comprehension when using the strategy, as compared to without the strategy.
In light of research linking repetition priming to increased neural processing efficiency, our results suggest that use of this compensatory strategy improves reading accuracy and comprehension by temporarily boosting phonologic activation levels.
PMCID: PMC2906786  PMID: 20664804
phonologic text alexia; repetition priming; aphasia; alexia; rehabilitation
17.  Subretinal electronic chips allow blind patients to read letters and combine them to words 
A light-sensitive, externally powered microchip was surgically implanted subretinally near the macular region of volunteers blind from hereditary retinal dystrophy. The implant contains an array of 1500 active microphotodiodes (‘chip’), each with its own amplifier and local stimulation electrode. At the implant's tip, another array of 16 wire-connected electrodes allows light-independent direct stimulation and testing of the neuron–electrode interface. Visual scenes are projected naturally through the eye's lens onto the chip under the transparent retina. The chip generates a corresponding pattern of 38 × 40 pixels, each releasing light-intensity-dependent electric stimulation pulses. Subsequently, three previously blind persons could locate bright objects on a dark table, two of whom could discern grating patterns. One of these patients was able to correctly describe and name objects like a fork or knife on a table, geometric patterns, different kinds of fruit and discern shades of grey with only 15 per cent contrast. Without a training period, the regained visual functions enabled him to localize and approach persons in a room freely and to read large letters as complete words after several years of blindness. These results demonstrate for the first time that subretinal micro-electrode arrays with 1500 photodiodes can create detailed meaningful visual perception in previously blind individuals.
PMCID: PMC3081743  PMID: 21047851
subretinal neuro-prosthetics; retinal implant; retinitis pigmentosa; blindness; artificial vision; bionic vision
18.  Insights from letter position dyslexia on morphological decomposition in reading 
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.
PMCID: PMC4490734  PMID: 26190985
morphological decomposition; Hebrew; letter position; inflection; derivation; letter position dyslexia; acquired dyslexia; developmental dyslexia
19.  Letters in the forest: global precedence effect disappears for letters but not for non-letters under reading-like conditions 
Normally skilled reading involves special processing strategies for letters, which are habitually funneled into an abstract letter code. On the basis of previous studies we argue that this habit leads to the preferred usage of an analytic strategy for the processing of letters, while non-letters are preferably processed via a holistic strategy. The well-known global precedence effect (GPE) seems to contradict to this assumption, since, with compound, hierarchical figures, including letter items, faster responses are observed to the global than to the local level of the figure, as well as an asymmetric interference effect from global to local level. We argue that with letters these effects depend on presentation conditions; only when they elicit the processing strategies automatized for reading, an analytic strategy for letters in contrast to non-letters is to be expected. We compared the GPE for letters and non-letters in central viewing, with the global stimulus size close to the functional visual field in whole word reading (6.5° of visual angle) and local stimuli close to the critical size for fluent reading of individual letters (0.5° of visual angle). Under these conditions, the GPE remained robust for non-letters. For letters, however, it disappeared: letters showed no overall response time advantage for the global level and symmetric congruence effects (local-to-global as well as global-to-local interference). We interpret these results as according to the view that reading is based on resident analytic visual processing strategies for letters.
PMCID: PMC4102249  PMID: 25101012
reading acquisition; global advantage effect; analytic processing; holistic processing; literacy; developmental dyslexia; congruence effect
20.  Letter Position Coding Across Modalities: The Case of Braille Readers 
PLoS ONE  2012;7(10):e45636.
The question of how the brain encodes letter position in written words has attracted increasing attention in recent years. A number of models have recently been proposed to accommodate the fact that transposed-letter stimuli like jugde or caniso are perceptually very close to their base words.
Here we examined how letter position coding is attained in the tactile modality via Braille reading. The idea is that Braille word recognition may provide more serial processing than the visual modality, and this may produce differences in the input coding schemes employed to encode letters in written words. To that end, we conducted a lexical decision experiment with adult Braille readers in which the pseudowords were created by transposing/replacing two letters.
Principal Findings
We found a word-frequency effect for words. In addition, unlike parallel experiments in the visual modality, we failed to find any clear signs of transposed-letter confusability effects. This dissociation highlights the differences between modalities.
The present data argue against models of letter position coding that assume that transposed-letter effects (in the visual modality) occur at a relatively late, abstract locus.
PMCID: PMC3467024  PMID: 23071522
21.  Pseudo-Synesthesia through Reading Books with Colored Letters 
PLoS ONE  2012;7(6):e39799.
Synesthesia is a phenomenon where a stimulus produces consistent extraordinary subjective experiences. A relatively common type of synesthesia involves perception of color when viewing letters (e.g. the letter ‘a’ always appears as light blue). In this study, we examine whether traits typically regarded as markers of synesthesia can be acquired by simply reading in color.
Methodology/Principal Findings
Non-synesthetes were given specially prepared colored books to read. A modified Stroop task was administered before and after reading. A perceptual crowding task was administered after reading. Reading one book (>49,000 words) was sufficient to induce effects regarded as behavioral markers for synesthesia. The results of the Stroop tasks indicate that it is possible to learn letter-color associations through reading in color (F(1, 14) = 5.85, p = .030). Furthermore, Stroop effects correlated with subjective reports about experiencing letters in color (r(13) = 0.51, p = .05). The frequency of viewing letters is related to the level of association as seen by the difference in the Stroop effect size between upper- and lower-case letters (t(14) = 2.79, p = .014) and in a subgroup of participants whose Stroop effects increased as they continued to read in color. Readers did not show significant performance advantages on the crowding task compared to controls. Acknowledging the many differences between trainees and synesthetes, results suggest that it may be possible to acquire a subset of synesthetic behavioral traits in adulthood through training.
To our knowledge, this is the first evidence of acquiring letter-color associations through reading in color. Reading in color appears to be a promising avenue in which we may explore the differences and similarities between synesthetes and non-synesthetes. Additionally, reading in color is a plausible method for a long-term ‘synesthetic’ training program.
PMCID: PMC3384588  PMID: 22761905
22.  Training Pseudoword Reading in Acquired Dyslexia: A Phonological Complexity Approach 
Aphasiology  2014;29(2):129-150.
Individuals with acquired phonological dyslexia experience difficulty associating written letters with corresponding sounds, especially in pseudowords. Previous studies have shown that reading can be improved in these individuals by training letter-sound correspondence, practicing phonological skills, or using combined approaches. However, generalization to untrained items is typically limited.
We investigated whether principles of phonological complexity can be applied to training letter-sound correspondence reading in acquired phonological dyslexia to improve generalization to untrained words. Based on previous work in other linguistic domains, we hypothesized that training phonologically “more complex” material (i.e., consonant clusters with small sonority differences) would result in generalization to phonologically “less complex” material (i.e., consonant clusters with larger sonority differences), but this generalization pattern would not be demonstrated when training the “less complex” material.
Methods & Procedures
We used a single-participant, multiple baseline design across participants and behaviors to examine phonological complexity as a training variable in five individuals. Based on participants' error data from a previous experiment, a “more complex” onset and a “less complex” onset were selected for training for each participant. Training order assignment was pseudo-randomized and counterbalanced across participants. Three participants were trained in the “more complex” condition and two in the “less complex” condition while tracking oral reading accuracy of both onsets.
Outcomes & Results
As predicted, participants trained in the “more complex” condition demonstrated improved pseudoword reading of the trained cluster and generalization to pseudowords with the untrained, “simple” onset, but not vice versa.
These findings suggest phonological complexity can be used to improve generalization to untrained phonologically related words in acquired phonological dyslexia. These findings also provide preliminary support for using phonological complexity theory as a tool for designing more effective and efficient reading treatments for acquired dyslexia.
PMCID: PMC4467909  PMID: 26085708
acquired dyslexia; phonology; complexity; sonority; pseudowords
23.  Effects of Tactile–Kinesthetic Stimulation on Low Birth Weight Neonates 
Iranian Journal of Pediatrics  2013;23(3):289-294.
Low Birth Weight [LBW] (1500gr ≤ Birth Weight ≤ 2499 gr) is one of the most serious health problems in neonates. These neonates need complementary interventions (e.g. tactile-kinesthetic stimulation) to promote development. This study was conducted to determine the effect of Tactile-Kinesthetic Stimulation (TKS) on physical and behavioral development of Low Birth Weight neonates.
This was a randomized controlled trial with equal randomization (1:1 for two groups) and parallel group design. Forty LBW neonates were randomly allocated into test (n = 20) and control (n = 20) groups. TKS was provided for three 15 minute periods per day for 10 consecutive days to the test group, with the massages consisting of moderate pressure strokes in supine and prone position and kinesthetic exercises consisting of flexion and extension of limbs. All measurements were taken before and after completion of the study with the same equipment (Philips electronic weighing scale with an accuracy of ±5 grams and Brazelton Neonatal Behavioral Assessment) and by the same person.
There was a trend towards increased daily weight gain, but without statistical significance. On the Brazelton scale, the test group showed statistically significant improved scores on the ‘motor’ (P-value <0.001) and ‘regulation of state’ (P-value = 0.039) clusters after the 10 days TKS.
TKS has no adverse effects on physiologic parameters and gives better adaptive behavior of LBW neonates compared to those without TKS.
PMCID: PMC3684473  PMID: 23795251
Tactile Stimulation; Kinesthetic Stimulation; Low Birth Weight; Neonatal Behavioral Assessment Scale
24.  Training Synesthetic Letter-color Associations by Reading in Color 
Synesthesia is a rare condition in which a stimulus from one modality automatically and consistently triggers unusual sensations in the same and/or other modalities. A relatively common and well-studied type is grapheme-color synesthesia, defined as the consistent experience of color when viewing, hearing and thinking about letters, words and numbers. We describe our method for investigating to what extent synesthetic associations between letters and colors can be learned by reading in color in nonsynesthetes. Reading in color is a special method for training associations in the sense that the associations are learned implicitly while the reader reads text as he or she normally would and it does not require explicit computer-directed training methods. In this protocol, participants are given specially prepared books to read in which four high-frequency letters are paired with four high-frequency colors. Participants receive unique sets of letter-color pairs based on their pre-existing preferences for colored letters. A modified Stroop task is administered before and after reading in order to test for learned letter-color associations and changes in brain activation. In addition to objective testing, a reading experience questionnaire is administered that is designed to probe for differences in subjective experience. A subset of questions may predict how well an individual learned the associations from reading in color. Importantly, we are not claiming that this method will cause each individual to develop grapheme-color synesthesia, only that it is possible for certain individuals to form letter-color associations by reading in color and these associations are similar in some aspects to those seen in developmental grapheme-color synesthetes. The method is quite flexible and can be used to investigate different aspects and outcomes of training synesthetic associations, including learning-induced changes in brain function and structure.
PMCID: PMC4126805  PMID: 24638033
Behavior; Issue 84; synesthesia; training; learning; reading; vision; memory; cognition
25.  Sensory factors limiting horizontal and vertical visual span for letter recognition 
Journal of Vision  2014;14(9):23.
Reading speed for English text is slower for text oriented vertically than horizontally. Yu, Park, Gerold, and Legge (2010) showed that slower reading of vertical text is associated with a smaller visual span (the number of letters recognized with high accuracy without moving the eyes). Three possible sensory determinants of the size of the visual span are: resolution (decreasing acuity at letter positions farther from the midline), mislocations (uncertainty about the relative position of letters in strings), and crowding (interference from flanking letters in recognizing the target letter). In the present study, we asked which of these factors is most important in determining the size of the visual span, and likely in turn in determining the horizontal/vertical difference in reading when letter size is above the critical print size for reading. We used a decomposition analysis to represent constraints due to resolution, mislocations, and crowding as losses in information transmitted (in bits) about letter recognition. Across vertical and horizontal conditions, crowding accounted for 75% of the loss in information, mislocations accounted for 19% of the loss, and declining acuity away from fixation accounted for only 6%. We conclude that crowding is the major factor limiting the size of the visual span, and that the horizontal/vertical difference in the size of the visual span is associated with stronger crowding along the vertical midline.
PMCID: PMC4144171
visual span; crowding; reading; vertical text; acuity; mislocation

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