RUNNING HEAD: RAPID NAMING AND DYSLEXIA 1
Dyslexia and fluency:
Parafoveal and foveal influences on rapid automatized naming.
Manon W. Jones
Bangor University
Jane Ashby
Central Michigan University
Holly P. Branigan
University of Edinburgh
Authors’ Note
Correspondence about the paper can be directed to M.W. Jones, School of Psychology,
Adeilad Brigantia, Penrallt Road, Gwynedd LL57 2AS, United Kingdom, email:
This research was funded in part by grants from the Economic and Social Research
Council (RA-000-23-3533). We would like to thank Chuck Clifton for his support during
several phases of this project and Jeff Kinsey for developing the software used in this
study.
KEYWORDS: Dyslexia; fluency; rapid automatized naming; foveal; parafoveal; linear
mixed effects; eye movements.
Word count: 9052 (Abstract, main text body and references)
RUNNING HEAD: RAPID NAMING AND DYSLEXIA 2
ABSTRACT
Fluent reading requires the ability to coordinate serial processing of multiple
items, an ability known to be impaired in dyslexia. Using a serial naming task that has
been shown to index reading fluency, we investigated which aspects of rapid serial
naming are impaired in dyslexia. In two display change experiments, we recorded eye
movements and voice onsets as adult dyslexic and non-dyslexic readers named letters in
an array that included letter pairs which were orthographically and phonologically
confusable (similar). Confusable information was presented parafoveally (Experiment 1a)
and foveally (Experiment 1b) in the second letter of each confusable pair. Linear mixed
effects analyses showed that orthographic and phonological similarity slowed the
processing of dyslexic readers more than non-dyslexic readers. Orthographic effects
arose when orthographically confusable letters were presented in the parafovea, whereas
phonological effects arose when phonologically confusable letters appeared in the fovea.
We discuss how these findings contribute to our understanding of fluency impairments in
high-functioning, dyslexic adults.
RUNNING HEAD: RAPID NAMING AND DYSLEXIA 3
TITLE: Dyslexia and fluency: Parafoveal and foveal influences on rapid automatized
naming
A key characteristic of skilled reading is the ability to read fluently, and slow,
effortful reading is often the only remaining indicator of developmental dyslexia in high-
functioning dyslexic adults, who are reading at the college level (Shaywitz & Shaywitz,
2008). Poor reading fluency in adults and children can be predicted by performance on a
rapid automatized naming task (RAN; Denckla & Rudel, 1976), which involves the serial
naming of letters, digits, objects or colours arranged in a 50 item array. This apparently
simple task is nevertheless problematic for dyslexic readers, who have consistently
slower naming times than unimpaired, non-dyslexic readers (e.g., Denckla & Rudel,
1976; see Wolf & Bowers, 1999, for a review). Thus RAN-type assessments are used to
identify children who are likely to be slow readers.
Researchers have used RAN-type tasks to examine the cognitive processes that
support reading fluency in non-dyslexic readers and impair fluency in dyslexic readers
(e.g., Jones, Branigan, Hatzidaki, & Obregon, 2010; Jones, Obregon, Kelly, & Branigan,
2008; Lervåg & Hulme, 2009; Parilla, Kirby, & McQuarrie, 2004; Powell, Stainthorp,
Stuart, Garwood, & Quinlan, 2007). The present study offers an initial investigation into
how parafoveal and foveal processes operate online during rapid serial naming. We
monitored the eye movements of dyslexic and non-dyslexic adult readers as they
completed a RAN-type task. In order to disentangle the influences of parafoveal and
foveal information in serial naming speed, letter arrays were presented using a display
change paradigm (Rayner, 1975) that controlled whether potentially confusable
information appeared parafoveally or foveally (see Figure 1). As confusable information
RUNNING HEAD: RAPID NAMING AND DYSLEXIA 4
was available exclusively in either parafoveal view or foveal view, this novel approach
allowed an examination of the distinct contributions of each stream of information to
serial naming speed, and potentially to reading fluency. Our data offer initial evidence
that fundamental parafoveal and foveal processes operate differently in dyslexics than in
typical readers.
Rapid serial naming appears to tap a microcosm of the processes underpinning
reading fluency, including: attention, feature detection, the activation of orthographic
representations, the integration of visual and phonological information, and motor
activation leading to articulation (Wolf & Bowers, 1999; Misra, Katzir, Wolf, &
Poldrack, 2004). It is therefore important to examine the various processing requirements
of rapid serial naming in order to discover why dyslexic readers are poor performers, as a
step in understanding basic impairments in reading fluency separated from word and
sentence level influences.
One consistent finding emerging from several studies is that RAN-type tasks are
most effective at discriminating good and poor readers’ performance when the stimuli
(e.g., letters) are presented simultaneously in an array rather than as discrete, individual
letters (e.g., Bowers & Swanson, 1991; Jones, Branigan, & Kelly, 2009). Moreover,
evidence shows that when stimuli are presented simultaneously, naming speeds for
individual stimuli are influenced by information associated with adjacent letters in the
array (Jones et al., 2008). These findings suggest that one key determinant of fluency
may be the way in which the reader manages to process parafoveal and foveal
information in contexts where more than one stimulus is present.
RUNNING HEAD: RAPID NAMING AND DYSLEXIA 5
Serial naming and fluency. When we read words aloud we largely concentrate
our cognitive resources on the task of identifying the word we are looking at (the ‘target’
item), which is then articulated. However, even before we have initiated articulation of
the target item, we have moved our eyes to fixate on the next item to be processed. This
is the case in reading (e.g., Laubrock, Engbert, & Kliegl, 2005) and in object naming
(Morgan, van Elswijk, & Meyer, 2008).
It is currently unclear to what extent, and how, processing the ‘next’ item to the
right in a series of words and objects overlaps with the processing of the target item. In
the reading literature, researchers debate whether processing of consecutive words is
serial or parallel (see Engbert, Nuthmann, Richter, & Kliegl, 2005, and Reichle, Rayner,
& Pollatsek, 2003, for reviews). In the language production literature, Meyer and
colleagues have shown in a series of object-naming studies that information from
adjacent objects can influence target item viewing and naming times, suggesting parallel
phonological processing of object names (e.g., Morgan & Meyer, 2005; Morgan, van
Elswijk, & Meyer, 2008; Malpass & Meyer, 2010). In letter naming tasks, when adjacent
items in an array are orthographically or phonologically confusable, this confusability
lengthens fixation time and naming latency for the target item (Jones et al., 2008; see also
Compton, 2003, for further evidence of reading group differences on ‘visual’ and
‘phonological’ versions of RAN). Participant responses are slower when adjacent letters
are similar orthographically (e.g., p vs q) or phonologically (e.g., k vs q). Crucially for
our current purposes, these studies found that dyslexic readers naming times are slowed
significantly more than non-dyslexics when the adjacent items in the array are
orthographically and phonologically confusable. These findings and others (e.g., Powell
RUNNING HEAD: RAPID NAMING AND DYSLEXIA 6
et al., 2007) suggest that dysfluency in RAN reflects a more complex problem than just
retrieval of phonological codes (Wagner, Torgesen, Laughon, Simmons, & Rashotte,
1993).
However, we have yet to resolve how the orthographic and phonological
information in two adjacent items intersect with each other and influence processing and
naming times. Do such effects occur during the initial, parafoveal processing of the
neighbouring item, or during later processing when the neighbouring item is fixated?
Further, are the influences of orthographic and phonological processing dissociable, such
that each exerts an independent influence on fluency but on different aspects of item
processing? Or do orthographic and phonological information influence target item
processing and naming similarly in each case? Answering these questions will help us
ascertain how item processing during serial naming influences reading fluency, and
precisely why serial naming is difficult for dyslexic readers.
We conducted two experiments to examine the extent of processing overlap
between orthographic and phonological processing of two adjacent letter items. The
second item in each pair was manipulated so that it was either confusable or non-
confusable with the first item in the pair in a RAN-type serial naming task. In particular,
we were interested in pinpointing the factors that result in the impaired performance of
dyslexic readers as compared to their non-dyslexic peers. Experiment 1a examined
orthographic and phonological influences in parafoveal processing, in which the second
item was parafoveally confusable with the first item; whereas Experiment 1b examined
orthographic and phonological influences in foveal processing, in which the second item
was foveally confusable with the first item. Foveal and parafoveal vision are defined with
RUNNING HEAD: RAPID NAMING AND DYSLEXIA 7
respect to the focus of attention. Foveal vision extends out approximately 1 degree in
either direction (2 degrees in total) from the centre of vision, and is the only region in the
visual field allowing 100% acuity. Parafoveal vision extends from about 1 degree out
from the center of vision to around 5 degrees, and displays somewhat reduced acuity
(Rayner, 1998).
Foveal processing occurs during fixation, and it plays a crucial role in object
naming and silent reading. Eye movement studies of silent reading initially identified the
importance of foveal processing. For example, readers were much slower to read text in
which the foveal information was unavailable than when it was available (Rayner &
Bertera, 1979). The foveal information available during fixation supports word
recognition and, thereby, affects text comprehension (Rayner, 1998; 2009). Production
studies indicate that foveal processing is essential in naming as well. Speakers rarely
name an item without first fixating it (Griffin & Bock, 2000; Jones et al., 2008; Meyer,
van der Meulen, & Brooks, 2000). Furthermore, single object naming experiments
suggest that word selection and phonological encoding processes operate foveally.
Speakers gaze longer at objects with relatively inaccessible names (e.g., flute), than they
do when producing more accessible object names (e.g., arm) (Griffin & Bock, 2000;
Meyer et al., 1998; Meyer & van den Meulen, 2000). Gaze length also reflects assembly
of phonological codes in fluent speech that involves multiple referents. Speakers gaze for
longer at lower frequency and lower codability items, even when the critical item occurs
in the middle of a description (Griffin, 2001).
While the eyes are fixated on one object or word, viewers automatically begin
parafoveally processing information at the next location they will fixate. Multiple-object
RUNNING HEAD: RAPID NAMING AND DYSLEXIA 8
naming studies demonstrate that participants activate phonological information associated
with an object that they have not yet fixated but that they will name next (Morgan &
Meyer, 2005; Morgan et al., 2008; Malpass & Meyer, 2010). Eye movement data
collected during silent reading indicate that readers extract linguistic information from
parafoveal stimuli within 140 ms during the pre-target fixation (Inhoff, Eiter, & Radach,
2005; Sereno & Rayner, 2000). Readers use coarse-grained parafoveal information, such
as word length, to direct eye movements during reading (e.g., Jones, Kelly, & Corley,
2007; Rayner, 1998). Skilled readers use parafoveal phonological information, such as
initial syllable information, to facilitate word recognition during silent reading (Ashby,
2006; Ashby & Rayner, 2004). Other phonological information, such as the number of
syllables, helps to control where the eyes will fixate next during reading (Fitzsimmons &
Drieghe, 2011; Ashby & Clifton, 2005).
Previous research suggests a relationship between reading skill and parafoveal
processing. Whereas skilled readers benefit from phonologically similar parafoveal
previews (Pollatsek, Lesch, Morris, & Rayner, 1992; Ashby, Treiman, Kessler & Rayner,
2006), poor readers do not show phonological preview benefits during reading (Chace,
Rayner, & Well, 2005). Letter categorisation is also more difficult for dyslexic readers,
compared with non-dyslexics, when the item is flanked by other stimuli, suggesting
parafoveal processing impairment in a lateral masking task (Pernet, Valdois, Celsis, &
Demonet, 2006). Therefore, it may be that dyslexic readers process parafoveal
information differently from non-dyslexic readers. Recent research demonstrates that
compensated dyslexic readers are sensitive to parafoveal information (Jones et al., 2008),
and that it may in fact act as a source of interference in their naming (Jones et al., 2009).
RUNNING HEAD: RAPID NAMING AND DYSLEXIA 9
To further examine the influences of parafoveal and foveal information on serial
naming in dyslexic readers, we conducted two eye movement experiments that presented
40 letters in a RAN-like array. We used these multi-letter displays to pinpoint the specific
processes that contribute to slow serial naming in dyslexic readers, and thus to identify
the possible processes that contribute to reading fluency impairments (or slow reading in
dyslexics). An eye–contingent, display change paradigm (Rayner, 1975) controlled when
the confusable information appeared (parafoveally or foveally). To our knowledge, this is
the first serial naming study to utilize display changes in letter arrays in order to examine
the parafoveal and foveal processes that occur during rapid serial naming. This
methodological development is important for studying a ‘continuous’ naming paradigm,
and it allows the generalization of our results to offline assessments, such as the RAN
(Denckla & Rudel, 1976) or Rapid Letter Naming (Wagner, Torgesen, & Rashotte,
1999), that have established slow serial naming speed as an indicator of reading
difficulties (Schatschneider, Fletcher, Francis, Carlson, & Foorman, 2004; Wimmer &
Mayringer, 2002; Wolf & Bowers, 1999).
Experiment 1a: How does parafoveal information influence serial naming speed?
Experiment 1a examined whether information gained exclusively from parafoveal
vision (i.e., early processing) influences processing times and/or the onset of articulation
times in a RAN task. We compared the performance of age-matched, high-functioning
adult groups of non-dyslexic and dyslexic readers on a RAN-letters task that manipulated
parafoveal information. Specifically, we manipulated whether the parafoveal information
available to readers in position n+1 was orthographically or phonologically confusable
RUNNING HEAD: RAPID NAMING AND DYSLEXIA 10
with the information presented in position n, and measured whether confusability affected
participants’ eye movements compared to conditions in which the parafoveal information
was neither orthographically nor phonologically confusable.
The design of this experiment was in many respects similar to the design of Jones
et al. (2008): Letters were presented in an array of four lines containing ten items each,
and confusability was manipulated by varying the orthographic similarity of adjacent
pairs of letter shapes (e.g., p-q; b-d) and the phonological similarity of the onset in the
letter names (e.g., q-k; g-j). However, unlike in Jones et al. (2008), we used a contingent
change paradigm, so that confusable information was presented only parafoveally: When
the participant actually fixated the location where the confusable information had
appeared, the confusable letter was replaced by a non-confusable letter. For example, in
the orthographically confusable condition, when a participant fixated the target item q (in
position n), the orthographically confusable letter p was viewed in the parafovea (in
position n+1). When the eyes saccaded across an invisible boundary to the immediate
right of the target item in position n, the confusable letter p (or non-confusable letter k) in
position n+1 was replaced by a non-confusable target item, such as f (see Figure 1).
[INSERT FIGURE 1 ABOUT HERE]
To study the effects of parafoveal confusability, we used two measures. As in
Jones et al. (2008), the processing time measure is the sum of all fixations on a letter
before the eye saccades away from it. This measure, which is also known as first-pass
duration, is thought to include processing stages from visual information uptake to
RUNNING HEAD: RAPID NAMING AND DYSLEXIA 11
activation of phonological codes (Griffin, 2001, 2004). Our second measure was eye-
voice span, or time from the onset of the first fixation on a letter to the onset of the
articulatory response for that letter. This measure, also known as naming latency,
includes the time taken to identify the letter and to complete the phonological assembly
and articulatory planning of its name. Thus, the eye-voice span measure reflects
processing time plus additional processing stages up to the point of articulation of the
correct item. Previous research indicates that the eye looks at least one object ahead of
the verbalized object (Griffin, 2004; Laubrock et al., 2008). In our previous serial naming
study, eye-voice spans were at least 200 ms longer on average than the processing time
measure (Jones et al., 2008). Thus, eye-voice span incorporates relatively later processes
that are specific to speech production (Levelt, Roelofs, & Meyer, 1999).
In skilled reading, it is well established that orthographic and phonological
information are initially processed parafoveally (Pollatsek & Rayner, 1992; see Rayner,
Pollatsek, Ashby, & Clifton, 2012 for a review of this literature). We examined whether
parafoveal processing contributed to the effects observed in Jones et al. (2008).
Therefore, we predicted that non-dyslexic readers would yield longer processing times in
response to confusable compared with non-confusable items. For dyslexic readers, we
predicted longer eye-voice spans in response to confusable compared with non-
confusable items (and compared with non-dyslexics’ eye-voice spans to these items). The
precise pattern of effects would also be informative about the nature of parafoveal
confusability, and specifically whether such effects are associated with orthographic
confusability, phonological confusability, or both.
RUNNING HEAD: RAPID NAMING AND DYSLEXIA 12
Group differences in processing speeds and eye-voice spans were measured on
item n (NEXT confusability, in which latency on the first item in the pair is measured)
and on item n+1 (PREV confusability, in which latency on the second item in each pair is
measured). As Jones et al. (2008) found that confusability effects extended in both
directions (i.e., both groups showed an effect when a confusable item appeared before a
target item and when it appeared after a target item), we expected to find confusability
effects in the PREV and NEXT analyses for both groups of readers.
Method
Participants. Two groups of 16 native English-speaking students participated in
this study. The dyslexic-reader group comprised students with a formal diagnosis of
dyslexia (10 females; 6 males). They were assessed during primary or secondary
education (before the age of 16) by an educational psychologist. This assessment was
confirmed during their university career. The non-dyslexic-reader group comprised
students who reported no difficulties with speech or literacy (11 females; 5 males). The
groups did not differ in age (Dyslexic-reader group: mean = 21 years, SD = 1.99; Non-
dyslexic-reader group: mean = 21 years, SD = 1.42).
Design & stimuli. Both groups were tested on a battery of cognitive and literacy
measures. These tests were administered in order to ensure that these high-functioning
dyslexic readers were poorer than non-dyslexics on literacy-related tests, whilst obtaining
comparable results on IQ measures (Snowling, 2000). Tests included rapid (letter)
naming (Comprehensive Test Of Phonological Processing [CTOPP]; Wagner et al.,
1999), word recognition (Wide Range Achievement Test [WRAT-3]; Wilkinson, 1993),
RUNNING HEAD: RAPID NAMING AND DYSLEXIA 13
digit recall, assessing short-term and working memory (Miles, 1993). A spoonerism task
assessed phonological awareness (Hatcher, Snowling, & Griffiths, 2002). We also tested
participants on verbal (Vocabulary) and non-verbal (Block design) sections of the
Wechsler Adult Intelligence Scale – 3rd edition (WAIS-III; Wechsler, 1992). The
cognitive and literacy tests took approximately 25 minutes to administer.
We created 16 experimental trials, each comprising a 10 x 4 array of letters. Of
the 40 items in each array, 8 items (2 in each row) were subject to a gaze-contingent
display-change (Rayner, 1975). We manipulated the phonological and orthographic
confusability (confusable vs. non-confusable) of parafoveal letters with respect to the
preceding letter in the array. Four trials in the experiment comprised orthographically
confusable items, in which letters were mirror images of one another on the vertical axis:
(p – q; b – d) and another four trials comprised phonological (onset) confusable items (g
– j (onset /dЗ/); k – q (onset /k/). Critical items were presented in positions n and n+1.
Four non-confusable equivalent trials were presented for both the phonological and
orthographic conditions (Orthographic: (P – Q; B – D; Phonological: g – k; j – q).1 Thus,
the same items appeared in phonologically non-confusable trials as in confusable trials;
the only difference was that confusable items appeared adjacent in confusable trials (e.g.,
g-j), but non-adjacent in non-confusable trials (e.g., g-k).
Note that orthographically non-confusable trials involved exactly the same
phonological output as the orthographically confusable trials: The same letters appeared
in the same order across conditions, differing only in letter case (e.g., orthographically
non-confusable: P-Q; orthographically confusable: p-q). In order to exclude any
explanation of a confusability effect in the orthographic condition based on letter case,
1 See footnote 1.
RUNNING HEAD: RAPID NAMING AND DYSLEXIA 14
letters in the phonological sets were also upper case on half of the trials (between-
participants). Our design yielded a possible 32 data points per cell.
The gaze-contingent display-change meant that confusable information in position
n+1 could be viewed only in the parafovea (whilst the participant was fixating the letter
in position n). For example, if the participant fixated on the letter q as the first member of
a target pair, it was possible for them to view the confusable item p parafoveally until the
eye crossed the invisible boundary line between positions n and n+1. Crossing the
boundary triggered a display change, such that the item in position n+1 changed to an
item that was not confusable with the first member of the pair. In all trials, letters in
position n+1 that had previously been confusable with letter item n changed into non-
confusable letter items: f or l. Filler items included the letter z and the letters f and l were
presented (at least once in each trial) to avoid the sequence becoming too predictable.
Four between-subjects lists were created in order that the order of confusable pairs could
be counterbalanced (e.g., p – q and q – p) in addition to the position of target items within
the 4 x 10 letter arrays.
The experiment yielded a 2 (dyslexic vs. non-dyslexic) x 2 (confusable vs. non-
confusable) design for the phonological-onset letter pairs and for the orthographic letter
pairs. Analyses were conducted for processing time and eye-voice span measures,
resulting in four analyses in total.
Apparatus. Eye movements were monitored by an SR Research Eyelink 1000
eyetracker. Fixation position was sampled at 1000Hz and saccades prior to critical
fixations were detected using a 17-sample saccade detection model with a velocity
threshold of 30 °/sec, an acceleration threshold of 8000 °/sec2, and a minimum amplitude
RUNNING HEAD: RAPID NAMING AND DYSLEXIA 15
of 0.5°. Viewing was binocular, but only the right eye was tracked. The letter arrays were
presented using custom designed software (Eyetrack 0.7.10k) on a 21 inch Iiyama
HM204DTA CRT monitor at a viewing distance of 60 cm. Each 10 x 4 array was
presented as white text on a black background. Each letter was presented in 18 point font
(1:6 spacing) and subtended a visual angle of 0.5° x 0.5° (the region of interest allocated
for each item comprised 76 pixels horizontally). Lines in the array were triple-spaced.
The gaze-contingent boundary was placed immediately to the right of a letter item in
position n, with a visual angle of 3° between the boundary line and the letter item in
position n+1. The centre-to-centre distance between each item was 3.5°. The position of
gaze-contingent pairs in a line varied within and across trials. The monitor displayed text
at a 150-Hz refresh rate that permitted display changes within 6 ms. The display change
completed during the saccade, and participants rarely noticed any change other than a
screen flicker. Participants’ spoken output was recorded on the PC via a Direct X sound
card; recording began automatically at the beginning of the trial and terminated at the end
of the trial. Speech onsets were subsequently obtained using professional sound editing
software (a script was used to record onsets when the sound wave reached a specified
intensity).
Procedure. The experiment began with adjustment of the infrared cameras
attached to the eyetracker, followed by a brief calibration procedure in which participants
viewed dots in 9 screen locations. Calibration was checked before each trial and the
recalibration procedure was repeated as necessary between trials to maintain accuracy.
Each trial in the experiment began with a drift correction (comprising a small square) in
the same position as the first object to be named (top left hand corner of the screen).
RUNNING HEAD: RAPID NAMING AND DYSLEXIA 16
When the participant’s eye fixated the square, it automatically triggered presentation of
the next trial in the experiment. Participants were instructed to name each item, starting
from the top left hand object and moving as quickly as possible in a left-to-right and
down fashion until they got to the final item, whereupon they were instructed to terminate
the trial with a button press. The experiment was self-paced. A total of 32 trials (10 x 4
grids) were presented in one experimental session (16 trials from the parafoveal
experiment described here were interspersed with 16 trials from the foveal experiment;
see Experiment 1b below). Trial presentation was randomized and a session lasted
approximately 30 minutes.
Results and Discussion
Cognitive and literacy tests Dyslexic readers showed significantly poorer
performance on the RAN measures and the single word reading measure than did the
non-dyslexic readers. Significant group differences were also found on memory tasks
(Forward and Backward digit span). Critically, the dyslexic group did not show a
significant difference on measures of global intelligence (WAIS Vocabulary and Block
design). Group differences did not reach significance on the phonological awareness
measure (Spoonerisms). Each member of the dyslexic group obtained a RAN score
(composite of Letters and Digits) that was at least 1.5 SD below the non-dyslexic mean
RAN score. None of the dyslexic readers in this study were therefore excluded from the
main analyses. Table 1 shows group difference scores on each test.
[INSERT TABLE 1 ABOUT HERE]
RUNNING HEAD: RAPID NAMING AND DYSLEXIA 17
Eye-movement parameters, speech onsets & analyses. The eye-movement
parameters used in this experiment were similar to those used in Jones et al. (2008).
Using the region of interest allocated to each item, we could determine when, with
reference to a zero point representing the beginning of the trial, the participants’ gaze
entered each region and how long the participant stayed in each region before saccading
to the next region.
Correct speech responses were matched to the relevant eye fixation data in order
to calculate eye-voice spans for each item (speech responses were measured relative to
the same zero point as the eye-fixation data). Approximately 17% of the data was
excluded owing to track losses. This figure is commensurate with recent reports of track
losses in the contingent change literature (e.g., White, Rayner, & Liversedge, 2005).
Two measures were calculated: First, processing time (first pass reading time;
Rayner, 1998) measured the time spent fixating each item before the eye saccaded to the
next item. Second, the eye-voice span measured the time between the onset of the first
fixation on a letter to the onset of articulation of the letter name. The processing time and
eye-voice span measures included only correctly named letters that were preceded or
succeeded by a related or unrelated item.
Linear Mixed Effects (LME) models were used to analyse the data (see Baayen,
2008; Baayen, Davidson, & Bates, 2008), implemented with lme4 (Bates, Maechler, &
Dai, 2008), and languageR packages (Baayen, 2008) in R (R Development Core Team,
2008). LME models enable separation of the experimental manipulation(s) under
observation (fixed effects) from spurious or ‘random’ effects, which is a particularly
RUNNING HEAD: RAPID NAMING AND DYSLEXIA 18
useful method for analyzing data from heterogeneous groups (such as groups with
dyslexia) performing a complex task such as RAN (see Jones et al., 2008 for a detailed
account of the advantages of using LME for this type of research). Analyses (processing
time / eye-voice span) included two fixed effects: 1) Confusability (non-confusable vs.
confusable); and 2) Group (non-dyslexic vs. dyslexic). Non-dyslexic/non-confusable
conditions comprised the intercept (baseline condition) in each analysis, against which
other conditions were compared. A significant fixed effect of ‘confusability’ occurred if
the non-dyslexic/confusable condition contributed unique variance to the model beyond
the baseline condition. A significant fixed effect of ‘group’ occurred if the dyslexic/non-
confusable condition contributed unique variance to the model beyond the baseline
condition. Finally, an interaction occurred if the dyslexic/confusable condition
contributed unique variance to the model beyond that explained by the additive
contribution of the other conditions (non-dyslexic/ non-confusable + non-dyslexic/
confusable + dyslexic / non-confusable); in other words, an interaction indicated a greater
effect of confusability in the dyslexic group than would be expected on the basis of a) the
non-dyslexic group’s performance in the confusable condition and b) the dyslexic
group’s own performance in the non-confusable condition (also see Table 2 note).
For each dependent measure (i.e., processing time and eye-voice span), separate
analyses were conducted for NEXT-confusable and PREV-confusable effects (see Figure
1): ‘NEXT-confusable’ analyses considered response times to the first item (n) when the
next item in the array (n+1), was parafoveally confusable, relative to conditions when it
was not confusable. We assume that attention shifts to item n+1 when available,
presumably during a late phase of processing item n (Reichle et al., 2003). As in previous
RUNNING HEAD: RAPID NAMING AND DYSLEXIA 19
work, we associate NEXT-confusable effects with initial processing of item n+1
intersecting with processing of item n. In contrast, ‘PREV-confusable’ analyses
considered response times to item n+1 (when the previous item in the array, in position n,
was parafoveally confusable with the letter that appeared in position n+1, i.e., before it
was fixated, relative to conditions when it was not confusable). In earlier work we
associated PREV-confusable effects with the lingering effects of processing item n on
processing item n+1 (Jones et al., 2008).
Participant, item, character (letter), and other item variances were entered as
random effects measures. Since our task is essentially an uninterrupted stream of serial
item naming, every target item had both following and preceding neighbours that we
expected to influence the processing of the target item. For the other item random effect
variable we, therefore, grouped the target with the item on the other side. If our analysis
examined the effect of a preceding item on the target item, for example, we assigned the
effect of the succeeding item on the target item to the random effect variable other item.
Thus, we could measure the effect of the previous item on the target independently of any
additional influence from the item succeeding the target item.
For each analysis we report t-values for each coefficient and estimated
probabilities based on 10,000 Markov chain Monte Carlo (MCMC) samples. MCMCs are
recommended because of the difficulty in determining degrees of freedom corresponding
to each t-value for the model coefficients.
Processing time and eye-voice measures were positively skewed, and therefore
logged in order to normalize the distribution. The results of all analyses are presented in
Table 2. For the sake of clarity, we only discuss and graphically represent findings that
RUNNING HEAD: RAPID NAMING AND DYSLEXIA 20
were statistically significant in terms of confusability effects for non-dyslexic and
dyslexic groups (as these are the effects of crucial interest in this paper). However, we
note here that in most analyses, dyslexic readers were slower on both processing time and
eye-voice span measures (irrespective of the confusability manipulation), which is
consistent with previous findings (Jones et al., 2008).
[INSERT TABLE 2 HERE]
For the processing time measure, analyses of the orthographic conditions yielded
an interaction model best fit for the PREV-confusable analysis only (χ² (1) = 4.27, p
< .05; see Figure 2): Dyslexic readers were significantly slower to process a target item
(in position n+1) if it had been orthographically confusable when viewed in the
parafovea (t = 2.13, p < .05), than would be expected on the basis of a) dyslexic readers’
own performance on non-confusable items; and b) non-dyslexics’ performance on both
non-confusable and confusable items. All other processing time and eye-voice indicated
no significant differences in confusability effects between participant groups. Standard
deviations of the random effects variables in all reported analyses (additive / interaction
models) are presented in table format in Appendix A.
[INSERT FIGURE 2 ABOUT HERE]
Results from Experiment 1a indicate that the orthographic confusability of
parafoveal information slowed the processing times of dyslexic readers compared with
RUNNING HEAD: RAPID NAMING AND DYSLEXIA 21
non-dyslexic readers. Specifically, dyslexics had difficulty in inhibiting confusable
information from the previous item (n) in the array when they parafoveally processed the
following confusable item (n+1), even though the confusable information was no longer
present when item n+1 was fixated. In contrast, non-dyslexic readers’ mean processing
times were reduced by the presence of orthographically confusable information in the
parafovea (but note that the fixed effect comparison for orthographically confusable
versus non-confusable information for non-dyslexics was not significant). The present
data did not indicate any effects of orthographic confusability on eye-voice span.
Experiment 1b: How does foveal information influence serial naming speed?
Experiment 1b investigated the role of foveal information in rapid serial naming
by manipulating the foveal confusability between neighbouring items in the array. Here
the second item in a target pair was non-confusable when viewed in the parafovea but
became confusable with the first item in the pair when it was fixated. Items viewed in the
fovea are subject to more in-depth processing than items viewed in the parafovea (Rayner
& Pollatsek, 1989; Rayner et al., 2012). In this experiment, critical items were fully
processed in terms of retrieval of phonological codes and phonological assembly for
articulation (because the confusable item’s name was articulated); this was in contrast to
Experiment 1a, where confusable items in position n+1 need not be fully encoded for
articulation (because the confusable preview item name was not articulated).
Experiment 1b therefore investigated whether information gained exclusively
from foveal vision (i.e., during fixation) influences processing times and/or eye-voice
spans in a RAN-type task. As in Experiment 1a, we studied the effects of orthographic
RUNNING HEAD: RAPID NAMING AND DYSLEXIA 22
and phonological confusability in non-dyslexic readers, but our critical interest concerned
how confusability affected dyslexic readers. The same groups of age-matched, high-
functioning non-dyslexic and dyslexic readers performed a RAN-letters task that was
almost identical to Experiment 1a, except that the confusable item was presented
foveally. For example, when a participant fixated the letter q, a non-confusable item (e.g.,
f) was visible in the parafovea (in position n+1). When the eye saccaded across an
invisible boundary to the immediate right of the first item, the letter in position n+1 was
replaced by a letter that was confusable relative to the first item in the pair, such as p (see
Figure 3). Thus, the second item in the pair was not confusable when viewed in the
parafovea, but became confusable when fixated.
[INSERT FIGURE 3 ABOUT HERE]
NEXT-confusable analyses indicated an influence of foveal information from the
second item (n+1) on the complete phonological assembly of the first item (n). The
NEXT-confusable analysis could only yield meaningful results in the eye-voice span
measure, in which the eye’s lead ahead of the voice would have triggered the confusable
change in the second item before production processes completed on the first item. In
contrast, processing time on the first item would not register the effect of confusability in
the second item, as the eye would not have yet triggered display change that revealed its
confusability. PREV-confusable analyses indicated the influence of the first letter (n) in
the pair on the processing of the following item (n+1). Item n+1 became confusable with
RUNNING HEAD: RAPID NAMING AND DYSLEXIA 23
item n only upon fixation, in order that we could examine whether processing of item
n+1 was influenced by foveal processing of item n.
Experiment 1b examined whether foveal processing contributed to the
confusability effects found in earlier work on RAN performance (Jones et al., 2008), and
whether its contribution to naming is qualitatively different from that of parafoveal
processing (Experiment 1a). Our hypotheses for this experiment followed the same logic
as the hypotheses for Experiment 1a; we examined whether foveal processing contributed
to the effects observed in Jones et al. (2008). Therefore, we predicted that non-dyslexic
readers would yield longer processing times in response to confusable compared with
non-confusable items. For the dyslexic readers, we predicted longer eye-voice spans in
response to confusable compared with non-confusable items (and compared with non-
dyslexics’ eye-voice spans to these items). The precise pattern of effects would also be
informative about the nature of foveal confusability, and specifically whether such effects
are associated with orthographic confusability, phonological confusability, or both.
As Jones et al. (2008) found that confusability effects extended in both directions
(i.e., both groups showed an effect when a confusable item appeared before a target item
and when it appeared after a target item), we expected to find confusability effects in the
PREV and NEXT analyses of eye-voice span for both groups of readers. Such a finding
in the NEXT analyses would suggest that the time taken to initiate articulation of the first
item is influenced by processing features of the second item. We also expected significant
effects of confusability in the PREV-confusable analyses. This would suggest that
inhibiting confusable information from the first item is difficult and prolongs processing
of the item in the second position.
RUNNING HEAD: RAPID NAMING AND DYSLEXIA 24
Method
Participants. Participants who took part in Experiment 1a also took part in
Experiment 1b.
Design and stimuli. The design of Experiment 1b was identical to Experiment 1a
except for one crucial difference: In Experiment 1b, confusable information was visible
only in the fovea, as described above.
Procedure. The procedure of Experiment 1b was identical to Experiment 1a.
Results and Discussion
Processing time and eye-voice measures were logged in order to normalize the
distribution. The results of all analyses are presented in Table 3. As in Experiment 1a, we
only discuss and graphically represent results that were statistically significant in terms of
confusability effects for non-dyslexic and dyslexic groups. Standard deviations of the
random effects variables in all reported analyses (additive / interaction models) are
presented in table format in Appendix A.
[INSERT TABLE 3 HERE]
Processing time. The interaction model provided a marginally better fit in the
orthographic PREV-confusable analysis (χ² (1) = 3.00, p = .08) (see Figure 4). Non-
dyslexic readers looked longer at the second item when it was orthographically
confusable with the first item in the pair than when it was not (PREV-confusable: t =
2.80; p < .05). In contrast, dyslexic readers showed similar processing times for the
second item, irrespective of its orthographic confusability, (t = 1.96, p < .05).
RUNNING HEAD: RAPID NAMING AND DYSLEXIA 25
[INSERT FIGURE 4 ABOUT HERE]
Eye-voice span. A significant Group x Confusability interaction occurred in the
eye-voice span measures in the phonological-confusability conditions (PREV-confusable:
χ² (1) = 6.56, p < .01; NEXT-confusable: χ² (1) = 4.00, p < .05) (see Figure 5). Dyslexic
readers’ eye-voice spans were longer than would be expected compared with a) their
performance on non-confusable items; and b) non-dyslexics’ performance on both non-
confusable and confusable items. This occurred in both NEXT-confusable (t = 2.01; p
< .05) analyses and PREV-confusable (t = 2.56; p < .05) analyses.
Results from Experiment 1b showed that whilst non-dyslexic readers’ processing
times were slowed as a function of foveal orthographic confusability, dyslexic readers
were relatively insensitive to the orthographic confusability manipulation. However,
dyslexic readers were significantly slower to initiate an articulatory response to the first
item in a target pair when the second item was phonologically confusable and, similarly,
were slower to name the second item when the first item was confusable. Thus,
phonological similarity in the names of the two fixated items impaired processes
associated with assembly of phonological codes in preparation for articulation (eye-voice
span).
[INSERT FIGURE 5 ABOUT HERE]
General Discussion
RUNNING HEAD: RAPID NAMING AND DYSLEXIA 26
One key characteristic of rapid naming is that it involves rapidly processing a
series of items. When naming a series of items, we process the fixated, foveal item and
some aspects of the upcoming, parafoveal item to its right (Morgan & Meyer, 2005). The
present study examined how parafoveal and foveal information contributes to rapid serial
naming speed, which is generally considered to index reading fluency (Schatschneider et
al., 2004; Wimmer & Mayringer, 2002; Wolf & Bowers, 1999). In order to examine how
orthographic and phonological information influenced rapid naming in normal and
dyslexic readers, we manipulated the orthographic or phonological confusability of
adjacent items online as participants named letters displayed in an array. Experiment 1a
investigated the effect of manipulating the confusability of n+1 when it appeared in
parafoveal view. Experiment 1b investigated the effect of manipulating the confusability
of n+1 when it appeared in foveal view. Data from these experiments provide clear
evidence that orthographic and phonological information obtained from parafoveal and
foveal sources affected eye-movements and eye-voice spans during serial naming.
Moreover, the nature and source of these confusability effects differed between reading
groups.
Non-dyslexic readers. Our typical readers did not exhibit orthographic or
phonological confusability effects for letters that were only confusable when in
parafoveal view (Experiment 1a). This could suggest that the non-dyslexics were able to
minimize any detrimental impact of parafoveal information, at least in this non-reading
context. This is consistent with previous research indicating that typical readers used
parafoveal information mainly to facilitate the identification of n+1 (Rayner, 2009).
The non-dyslexic readers were slower to process foveally confusable items when
RUNNING HEAD: RAPID NAMING AND DYSLEXIA 27
the target was orthographically similar to the previous item in the array than when it was
not (Experiment 1b). This finding suggests that during rapid serial naming in normal,
skilled readers, foveal processing of a stimulus can be influenced by the orthographic
features of the previous item (i.e., orthographic spillover effects). Studies of text reading
show that shared orthographic neighbourhoods increase target viewing times, an effect
particularly visible in later processing measures (total time and regressions) and which
has been attributed to lateral inhibition at the lexical level (e.g., Acha & Perea, 2008).
Our task required lexical retrieval of letter names, rather than words, but we propose a
similar explanation: Strong activation of an orthographic form immediately prior to the
target in this experiment inhibited activation of an orthographically similar
representation. Non-dyslexics’ sensitivity to orthographically confusable information that
appeared during a fixation is consistent with previous evidence of longer processing
times in response to adjacent orthographically confusable items (Jones et al., 2008). Non-
dyslexic readers were not, however, sensitive to phonological confusability in either
experiment.
Dyslexic readers. When dyslexics were presented with orthographically
confusable items (Experiment1a), parafoveal confusablility of the second letter resulted
in slower processing times on average when the second item was fixated. This finding
suggests that during rapid serial naming, dyslexics' processing of two consecutive letters
can be disrupted by parafoveal information from the second letter, compared with non-
dyslexics. This finding is consistent with previous evidence of dyslexic parafoveal
processing impairment in a lateral masking task (Pernet et al., 2006). Interestingly,
parafoveal orthographic confusability slowed processing times for the second item in the
RUNNING HEAD: RAPID NAMING AND DYSLEXIA 28
pair rather than for the first item, even though the second item was not confusable when
fixated. This suggests a lag in the interference from parafoveal information, which could
be attributed to slower parafoveal processing in dyslexics. Therefore, the dyslexic data
from Experiment 1a raises the possibility that sluggish parafoveal processing may
contribute to dyslexic readers’ problems with reading fluency. When the same
orthographically confusable information was only available foveally (in Experiment 1b),
dyslexic readers were not sensitive to orthographic confusability effects (although non-
dyslexic readers were).
In contrast, phonologically confusable information presented in foveal view
lengthened the eye-voice spans of dyslexic readers in Experiment 1b. This is consistent
with previous research suggesting problems with dyslexics’ retrieval of phonological
codes for production (Clarke et al., 2005; Jones et al., 2008; Wagner et al., 1993). Also,
these data indicate that foveal phonological confusability slows dyslexic readers’ naming
latencies in two situations: both in naming the target item whilst the eye has moved on to
the next, phonologically confusable item (i.e., activation of to-be-named phonological
codes disrupt phonological assembly on the target item), and in naming the target item
when the previous item in the array was phonologically confusable (i.e., failure to
disengage from already articulated phonological codes disrupts phonological assembly on
the target item).
Taken together, our results suggest that dyslexic readers experience a processing
bottleneck, in which they tend to experience greater difficulty than non-dyslexic readers
in selecting one representation from competing alternatives (e.g., that the letter q is a q as
opposed to a visually similar letter such as p, or a letter with a phonologically similar
RUNNING HEAD: RAPID NAMING AND DYSLEXIA 29
name such as k). Thus, during the early (parafoveal) stages of processing, dyslexic
readers are slower than non-dyslexic readers to activate one orthographic code among
several alternatives (or to distinguish between two very similar orthographic codes). At
later (foveal) stages of processing, when required to commit to a phonological code for
articulation, dyslexic readers have more difficulty selecting the appropriate phonological
code from competing alternatives. It seems likely that the confusability effects observed
in dyslexic readers stem from degraded orthographic and phonological representations,
which are more difficult to distinguish and therefore slower to select and retrieve (see
Perfetti, 2007). Our findings may reflect separate orthographic and phonological deficits,
each exerting independent influences and resulting in separate impairments (see Rayner
et al., 2012 for further discussion). Alternatively, it is possible that a single mechanism is
responsible for degraded representations in both domains.
This study extends our understanding of why dyslexic readers perform more
slowly on serial naming tasks than skilled readers. Jones et al. (2008) initially established
that the presence of orthographically confusable and phonologically confusable
information in adjacent letters increased letter naming latency in dyslexic readers,
however that study was not designed to discriminate parafoveal from foveal sources of
the confusability effects. The effects found in the present study are consistent with
findings from Jones et al. (2008), however the confusability effects found here were not
as pervasive as one might expect from previous research. For example, our dyslexic
readers did not yield longer eye-voice spans in response to orthographic as well as
phonological confusability, and our non-dyslexic readers did not show some of the
confusability effects reported in Jones et al. (2008). The more pervasive confusability
RUNNING HEAD: RAPID NAMING AND DYSLEXIA 30
effects in the previous experiment could be accounted for by differences in how each
study presented parafoveal and foveal information. The present study made confusable
information available either parafoveally or foveally; but the confusable information was
constantly available in Jones et al. (2008). Thus, finding more pervasive confusability
effects in our previous study may reflect the cumulative effect of processing the second
confusable item both parafoveally and foveally.
Implications. By independently manipulating whether the confusable information
was available parafoveally or foveally, the present study allowed us to examine closely
how the processing of orthographic and phonological information intersect across
successive items in a serial naming task. Our data identify two sources of the diagnostic
power of rapid serial naming tests to identify and predict dyslexia. First, dyslexic readers’
viewing times are slowed by confusable adjacent orthographic information in the
parafovea. Second, dyslexic readers’ naming latencies are delayed when confusable
phonological information is available in foveal view.
In summary, this study examined how foveal and parafoveal information
influences serial naming and impairs dyslexic readers’ naming speeds by manipulating
orthographic and phonological confusability. The findings suggest that dyslexics’
processing of orthographic and phonological information differs from non-dyslexics. The
dyslexic readers had difficulty distinguishing between multiple, activated orthographic
codes that appeared only in parafoveal view. They also had difficulty distinguishing
between multiple activated phonological codes that were foveally confusable during the
later, production stages of processing adjacent items.
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RUNNING HEAD: RAPID NAMING AND DYSLEXIA 39
Footnotes
1. Note that the items b-d are potentially confusable at the rime level as well as
the orthographic level. In a previous study, however, using identical letter pairs, we
showed that the rime confusability inherent in b-d does not contribute significant variance
naming speed. Furthermore, rime confusability in general does not appear to influence
RAN speeds: a specific rime confusability manipulation did not show any significant
effects in either dyslexic or non-dyslexic groups across several analyses (Jones et al.,
2008). On the basis of these results, we can therefore rule out an influence of rime.
RUNNING HEAD: RAPID NAMING AND DYSLEXIA 40
Table 1. Reading group scores on cognitive and literacy tests.
Dyslexic(16)
Non-dyslexic(16)
t Cohen’s d
Rapid letter naming
MeanSD
17.204.26
11.561.42
5.51*** 1.77
Rapid digit naming
MeanSD
17.204.67
11.051.23
5.08*** 1.80
Word reading MeanSD
46.318.07
53.871.62
3.67* 1.29
Spoonerisms MeanSD
21.259.22
23.001.74
0.74 0.26
Forward digit span
MeanSD
8.682.18
10.371.74
2.41* 0.85
Backward digit span
MeanSD
3.372.02
5.450.96
3.67** 1.31
WAIS – vocabulary
MeanSD
12.752.23
12.751.29
0.00 0.00
WAIS – block design
MeanSD
14.182.80
15.002.39
0.88 0.31
Note. RAN Letters and Digits = RTs (s); Word reading = correct /56, Spoonerisms =
correct /24; Verbal memory = correct: Forward digit span = /12; Backward digit span = /6
points. WAIS = scale scores. *** p < .001; ** p < .01; * p <.05.
RUNNING HEAD: RAPID NAMING AND DYSLEXIA 41
Table 2: Experiment 1a: Parafoveal confusability
Fixed Effect Phonological Orthographic
Processing time Eye-voice Processing time Eye-voice
PREV-
confusable
NEXT-
confusable
PREV-
confusable
NEXT-
confusable
PREV-
confusable
NEXT-
confusable
PREV-
confusable
NEXT-
confusable
Non-dyslexic/Non-confusable (1) baseline
Mean (SE)
460(420-501)
363(322-408)
736(675-803)
699(629-776)
489(437-543)
363(321-408)
745(680-814)
699(631-775)
Non-dyslexic/Confusable (2)
Mean (SE)t
469(443-496)0.67
382(353-416)1.49
725(678-779)0.47
697(658-740)0.09
466(434-502)1.45
385(355-416)1.73
734(690-782)0.52
705(665-750)0.31
Dyslexic/Non-confusable (3)
Mean (SE)t
565(499-637)3.05 **
464(403-535)3.27
817(737-910)1.86 *
837(752-935)3.09 **
544(474-628)1.36
459(392-529)2.82 **
838(751-941)1.92 *
839(760-939)3.17 **
Dyslexic/ Confusable (4)
Mean (SE)t
573(531-619)0.14
476(435-523)0.61
800(742-860)0.19
845(784-907)0.33
566(523-612)2.13 *
486(445-532)0.05
864(804- 925)1.27
881(823-945)1.13
Note. Fixed effects comparisons are made with reference to the baseline condition (non-
dyslexic/ non-confusable condition). A fixed effect of confusability involves comparison
of conditions (1) and (2); a fixed effect of group involves comparison of conditions (1)
and (3); an interaction involves comparison of the additive fixed effect factors: (1) + (2) +
(3) with condition (4). Mean and SE values = ms; * p < .05, ** p < .01.
RUNNING HEAD: RAPID NAMING AND DYSLEXIA 42
Table 3: Experiment 1b: Foveal confusability
Fixed Effect Phonological Orthographic
Processing time Eye-voice Processing time Eye-voice
PREV-
confusable
NEXT-
confusable
PREV-
confusable
NEXT-
confusable
PREV-
confusable
NEXT-
confusable
PREV-
confusable
NEXT-
confusable
Non-dyslexic/Non-confusable (1) baseline
Mean (SE)
478(435-531)
380(336-430)
804(729-887)
733(651-834)
452(411-497)
376(336-419)
758(691-824)
678(602-760)
Non-dyslexic/Confusable (2)
Mean (SE)t
483(446-518)0.31
382(349-419)0.13
829(769-897)0.85
737(668-819)0.12
490(459-522)2.80 *
357(328-389)1.34
782(727-837)0.99
689(642-739)0.56
Dyslexic/Non-confusable (3)
Mean (SE)t
603(528-685)3.19 **
472(411-543)2.85 **
887(785-999)1.51
840(750-939)2.31 *
582(513-658)3.70 **
443(385-503)2.34 **
893(807-995)2.86 **
828(740-934)3.15 **
Dyslexic/ Confusable (4)
Mean (SE)t
579(531-628)1.18
481(437-529)0.27
1017(935-1102)2.56 *
925(844-1009)2.0 *
582(538-631)1.96 *
457(415-501)1.74
920(856-986)0.05
815(749-882)0.8
Note. Fixed effects comparisons are made with reference to the baseline condition (non-
dyslexic/ non-confusable condition). A fixed effect of confusability involves comparison
of conditions (1) and (2); a fixed effect of group involves comparison of conditions (1)
and (3); an interaction involves comparison of the additive fixed effect factors: (1) + (2) +
(3) with condition (4). Mean and SE values = ms; * p < .05, ** p < .01.
RUNNING HEAD: RAPID NAMING AND DYSLEXIA 43
Figure 1. Parafoveal confusability manipulation experiment: Illustrative example of
NEXT and PREV analyses (orthographic-confusable and non-confusable conditions).
Note. The symbol denotes the eye position (pre- and post- display change) in
addition to the letter (n or n+1) measured (processing times and eye-voice spans). NEXT
analyses indicate the influence of parafoveal information from the next item (n+1),
affecting processing of item n late in its identification. PREV analyses indicate the
influence of n on the processing of n+1 (i.e., lingering effects of the pre-change
[parafoveally confusable] item).
RUNNING HEAD: RAPID NAMING AND DYSLEXIA 44
Figure 2. Processing times (ms) for Experiment 1a, which examined parafoveal confusability.
(A) An illustration of the orthographic confusability condition Previous analysis. The eye
symbol indicates the item measured. (B) Mean estimated coefficient exponential values
(ms) for each group in the orthographically non-confusable and confusable conditions
Note. * p < .05.
RUNNING HEAD: RAPID NAMING AND DYSLEXIA 45
Figure 3. Foveal confusability manipulation experiment: Illustrative example of NEXT
and PREV analyses (orthographic-confusable and non-confusable conditions).
Note. The symbol denotes the eye position (pre- and post- display change) in
addition to the item (n or n+1) measured (processing times and eye-voice spans). NEXT
analyses indicate the influence of foveal information from the second item (n+1),
affecting processing of the first item (n) late in its identification (eye-voice span measure
only). PREV analyses indicate the influence of the first item (n) on the processing of the
second item (n+1).
RUNNING HEAD: RAPID NAMING AND DYSLEXIA 46
Figure 4. Processing times (ms) for Experiment 1b, which examined foveal confusability.
(A) An illustration of the orthographic confusability condition Previous analysis. The eye
symbol indicates the item measured. (B) Mean estimated coefficient exponential values
(ms) for each group in the orthographically non-confusable and confusable conditions.
Note. * p < .05.
RUNNING HEAD: RAPID NAMING AND DYSLEXIA 47
Figure 5. Eye-voice spans for Experiment 1b, which examined foveal confusability.
(A) An illustration of the phonological confusability condition, Next and Previous
analyses. The eye-voice symbol indicates the item measured. (B) Mean estimated
coefficient exponential values (ms) for each group in the phonologically non-confusable
and confusable conditions.
Note. * p < .05.
RUNNING HEAD: RAPID NAMING AND DYSLEXIA 48
Appendix A
Standard deviations (log values) of random effects variables in Experiment 1a.
Variable Phonological Orthographic
Processing time Eye-voice Processing time Eye-voice
PREV-
confusable
NEXT-
confusable
PREV-
confusable
NEXT-
confusable
PREV-
confusable
NEXT-
confusable
NEXT-
confusable
PREV-
confusable
Participant 0.20 0.19 0.14 0.17 0.20 0.21 0.15 0.17
Item 0.03 0.01 0.02 0.04 0.00 0.00 0.00 0.04
Character 0.03 0.08 0.04 0.19 0.04 0.04 0.06 0.18
Other-item 0.05 0.05 0.06 0.05 0.03 0.03 0.03 0.04
Residual 0.37 0.45 0.34 0.36 0.38 0.38 0.11 0.35
Standard deviations (log values) of random effects variables in Experiment 1b.
Variable Phonological Orthographic
Processing time Eye-voice Processing time Eye-voice
PREV-
confusable
NEXT-
confusable
PREV-
confusable
NEXT-
confusable
PREV-
confusable
NEXT-
confusable
PREV-
confusable
NEXT-
confusable
Participant 0.21 0.19 0.19 0.17 0.30 0.17 0.18 0.14
Item 0.06 0.03 0.07 0.13 0.00 0.00 0.05 0.01
Character 0.03 0.10 0.07 0.19 0.04 0.08 0.21 0.05
Other-item 0.07 0.02 0.06 0.05 0.03 0.05 0.03 0.04
Residual 0.39 0.19 0.38 0.42 0.36 0.42 0.36 0.31