Children with disabilities have frequently participated in various
interventions before the efficacy of those practices was scientifically
validated. When subsequent scientific evidence failed to support
particular practices, those that had already made inroads into the
educational arena frequently continued to be used. Given the current
emphasis on the use of empirically validated interventions, a review of
research on the efficacy of educational interventions is consistent with
guidelines from the No Child Left Behind Act (2001) and the Individuals
with Disabilities Education Act (2004). The research findings regarding
three relatively common, yet controversial, practices failed to support
the continued use of perceptual motor programs, sensory integration
therapy, and tinted lenses. Educators are encouraged to become informed
consumers of research and implement evidence-based practices.
In recent years, journal articles and entire books have been
written to alert educators, parents, physicians, psychologists, and
other professionals of the inherent problems associated with the use of
nonvalidated practices in the treatment of individuals with disabilities
(e.g., Jacobson, Foxx & Mulick, 2005; Lilienfeld, Lynn, & Lohr,
2003; Rooney, 1991; Sieben, 1977; Silver, 1995; Stephenson, 2004). In
spite of efforts of those in the held to ensure that scientifically
validated interventions are the treatments of choice, nonvalidated
approaches continue to hold a considerable amount of influence on the
perceptions of many professionals and the public. The American Academy
of Pediatrics (1999) recommended training new physicians about
discredited practices, such as the Doman-Delacato patterning treatment,
to avoid repeating mistakes of the past. This is an important
recommendation that is just as relevant for educators as it is for
While the use of a nonvalidated approach may not pose an imminent
threat to the safety of individuals, it could deprive people of exposure
to effective interventions, waste valuable time, and provide false hopes
that may lead to feelings of discouragement after the approach fails to
produce the desired outcome. An internet search on the practices
discussed in this paper would lead the reader to many sites containing
persuasive advertisements and testimonials claiming the effectiveness of
the treatments without citing support from empirical research reported
in peer-reviewed papers. To this end, it is imperative that
professionals become informed consumers of research to ensure that those
seeking assistance are provided with treatments or interventions that
will most likely result in improved learning and an increased quality of
The purposes of this paper are twofold. First, the review will
consolidate available research evidence and inform professionals of the
lack of scientific substantiation for the continued use of three
controversial practices: perceptual motor programs (PMPs), sensory
integration, and tinted lenses. Second, parallels will be drawn between
these three approaches with the intent of assisting consumers of
research to understand why they continue to be employed and how to
identify potentially ineffective practices. The three practices
discussed in this review have been selected among the many unsupported
or controversial practices because there is a long history of their use
with students with disabilities and learning difficulties (Kavale &
Mostert, 2004; Whitely & Smith, 2001). It is our intention to draw
to the attention of practitioners the nature of the evidence available
on the efficacy of these practices. To achieve this goal, definitions of
each practice, a description of the procedures along with a rationale
for those procedures and relevant research findings will be presented
for each practice. Where systematic meta-analyses have been conducted
(i.e., PMPs and sensory integration), key reviews will be synthesized
and recent studies will be considered where relevant. Unlike PMPs and
sensory integration, tinted lenses have not been subject to systematic
meta-analysis so primary sources of research will be examined. Finally,
some common characteristics of these approaches will be discussed along
with an exploration of reasons they continue to be employed.
Perceptual Motor Programs
Perceptual motor skills are those that require the integration of
sensory input (visual, auditory, and kinesthetic) with fine or gross
motor responses. Perceptual Motor Programs (PMPs) for students who have
difficulty learning are based on the notion that neurological problems
causing particular processing deficits related to the integration of
perceptual and motor skills interfere with academic learning (Blythe,
2000; Dore, 2006). Despite professional concerns regarding the existence
of processing deficits, interventions for learning difficulties that
purport to remediate these underlying process deficits remain popular.
Perceptual-motor training has been the most prevalent type of process
training and remains alive and well (Kavale & Forness, 2000). Many
older PMPs such as the Doman-Delacato patterning program continue to be
advertised, although they have been discredited (American Academy of
Pediatrics, 1999; Jacobson, Mulick, & Foxx, 2005), and many newer
programs such as the Dore/DDAT, Primary Movement Program and Brain
Gym[R] have emerged with a range of theoretical underpinnings.
Description of Practice for Perceptual Motor Programs
Currently widely advertised programs such as the Dore Achievement
Center's individualized Dyslexia, Dyspraxia and Attention Treatment
(DDAT) are based on the claim that the difficulties lie in the
cerebellum (Dore, 2006). Treatment consists of exercise programs that
are claimed to improve the ability of the cerebellum to process
information. It is purported that children with dyslexia have a core
difficulty with skill automization, which impacts language and reading.
This difficulty has been called Cerebellar Developmental Delay (DDAT,
2006a) by the Dore centers, a label that is not used by any other group.
Dore centers claim that their individually designed exercise programs
improve cerebral functioning thereby overcoming automization deficits
and subsequently improving academic and social skills (DDAT, 2006b;
Fawcett, Nicolson, & Maclagan, 2001; Reynolds, Nicolson, &
Other current perceptual-motor theories ascribe difficulties in
learning to the persistence of primitive reflexes which then impede
normal development and the ability to learn skills such as reading and
writing (Goddard-Blythe, 2000; Institute for Neuro-Physiological
Psychology, n.d.; Jordan-Black, 2005; McPhillips, Hepper & Mulhem,
2000). These theories underlie the Primary Movement program developed by
McPhillips and programs promoted by the Institute for
Neuro-Physiological Psychology (INPP). Programs such as Brain Gym [R],
which are promoted as improving learning, sport and self management
skills in anyone (Brain Gym [R], 2006a), rely on much more general and
simplistic notions of improving brain function. Brain Gym [R] promotes
exercises claimed to facilitate the integration of the front and back
parts of the brain, the right and left hemispheres, and the top and
bottom parts of the brain to improve a wide array of unrelated behaviors
such as reading, surfing, golf, and sales. (Brain Gym[R], 2006b; Hyatt,
2007). In essence, PMPs imply that relatively simple exercises can
fundamentally change the neural structure of the brain and facilitate
PMP programs prescribe particular motor activities and exercises.
Some, such as in the Dore/DDAT program maybe individually prescribed and
adjusted (Reynolds et al., 2003), while others may be generic (Brain Gym
[R], 2006b). They often include activities, such as throwing and
catching, purported to improve balance, gross and fine motor skills, and
academic achievement. The exercises may involve doing two things at
once; for example, one exercise in the Dore/DDAT program involves
sitting and bouncing on a large air filled ball while tossing a bean bag
from hand to hand (DDAT, 2006a).
The persistence of primitive reflexes is another rationale given
for programs that prescribe exercises that mimic the activities of
fetuses and infants such as crawling and stretching or movements based
on those reflexes (Goddard-Blythe, 2005; Jordan-Black, 2005; McPhillips
et al., 2000). The claim is made that movements that follow the pattern
of the reflexes will work to inhibit those reflexes and somehow improve
the ability to acquire reading and other academic skills (McPhillips et
Research Findings for Perceptual Motor Programs
Kavale and Mattson (1983) completed a meta-analysis of 180 studies
of PMPs and found a very small overall effect size of .08. Effect sizes
were reported for outcome measures (reading, intelligence, general
achievement as well as perceptual and motor skills), specific training
programs, different groups of children, and different grade levels and
no important positive effects were found. Indeed the effect size for
perceptual-motor outcomes was only 0.17 which is also very small and
suggests that the programs examined had little impact even on
perceptual-motor skills themselves. The Board of the Trustees of the
Council for Learning Disabilities (Council for Learning Disabilities,
1987) issued a strong statement in 1986 against the use of perceptual
motor testing and training to improve academic performance, perceptual,
and perceptual-motor functions in students with learning disabilities.
They based this recommendation on the lack of scientific evidence
supporting such practices.
Hyatt (2007) reviewed the research on Brain Gym [R] and found that
the limited peer-reviewed research available failed to support claims
that Brain Gym [R] resulted in improvements in academic learning. There
are two reported studies of the DDAT exercise-based approach (Reynolds
et al., 2003; Reynolds & Nicolson, 2007) but the flawed research
design and difficulties with the analysis and inter-pretation of results
make the evidence supporting the efficacy of the approach unconvincing
(Alexander & Slinger-Constant, 2004; Rack, Snowling, Hulme &
Gibbs, 2007; Snowling & Hulme, 2003). Summaries of several small,
in-house studies in schools in the UK and Germany on the effects of a
program designed by the INPP to reduce the persistence of primitive and
postural reflexes and to improve academic performance, particularly
reading, were presented by Goddard-Blythe (2005). None of these studies
showed that the program had important effects on reading, and in most
sites there was no effect on reading.
There are two research studies (Jordan-Black, 2005; McPhillips et
al., 2000) that reported positive effects on reading and math but not
spelling after the use of the Primary Movement Programme developed by
McPhillips, but there are limitations to these studies and the results
need to be replicated by other researchers prior to acceptance. The
assessment of the persistence of primitive reflexes was carried out
using observation and scoring on a four point scale of the movement of
the arms in response to having the head turned (Schilder test). Neither
McPhillips et al. nor Jordan-Black provide information on the origins,
reliability, or validity for this test nor did they carry out
inter-observer agreement measures in their studies which would establish
that the same actions would be scored the same way by two independent
observers. Both reports also note that the reduction in the reflexes is
claimed only to increase "readiness" to learn and the program
is not a substitute for instruction. Given the lack of impact of older
PMPs on reading and that the exhaustive review of the correlates of
reading carried out by Hammill (2004) found only small correlations
between reading and perceptual-motor skills, it is hard to be optimistic
that these newer programs will be any more successful than the older
Sensory integration arose from the work of Ayres (see Ayres, 1972)
and was popularized in the 1970's. It has been applied to a variety
of groups including those with learning difficulties (Hoehn &
Baumeister, 1994), cerebral palsy (Chu, 1989), intellectual disability
(Arendt, MacLean, & Baumeister, 1988a) and autism (Dawson &
Watling, 2000). Much of the early research addressed children with
learning disabilities, with the expectation that underlying academic
performance would improve with sensory integrative therapy (Vargas &
Camilli, 1999). More recent research has often focused on addressing
unusual responses to sensory input, particularly in children with autism
spectrum disorders (see Baranek, 2002; Dawson & Watling, 2000). A
fundamental assumption underlying sensory integration is that learning
and other problems arise, at least in part, from difficulties in the
neurological processing of vestibular, tactile and proprioceptive
sensory information (Arendt et al., 1988a; Ayres, 1972; Bundy &
Murray, 2002; Hoehn & Baumeister, 1994). Higher-level functions,
such as those involved in traditional academic skills, are assumed to be
dependent on lower-level processing of sensory information (Hoehn &
Baumeister, 1994). The basic premise that higher cognitive and
functional skills are dependent on more fundamental abilities is common
among perceptual motor programs. Sensory integration, however, is
distinguished by the apparent complexity of its underlying
neurophysiological theory and thus it warrants separate consideration.
Description of Practice for Sensory Integration
Sensory integrative therapy is usually conducted by occupational
therapists and treatment is costly, with intervention sometimes lasting
more than a year (Vargas & Camilli, 1999). In a review of sensory
integration research, Vargas and Camilli reported that intervention
averaged 60 hours (range 13-180), involving between two and five
sessions per week, each of 25-45 min duration. Interventions involve a
range of activities that typically include the combination of controlled
sensory stimulation and "purposeful" motor activity (Ayres,
1972; Bundy & Murray, 2002; Hoehn & Baumeister, 1994). Therapy
may involve the use of equipment such as hammocks and scooter boards to
provide vestibular stimulation, use of weighted vests, manual
compression of joints, as well as brushing and rubbing of the body with
materials of various textures (see Ayres, 1972; Hoehn & Baumeister,
1994; Smith, Mruzek, & Mozingo, 2005). A related intervention
involves the use of "sensory diets", including activities and
environmental adjustments, which are presumed to match the
individual's sensory needs (Smith et al., 2005). For example, if a
child is over-aroused, calming vestibular activities such as rocking or
riding a bike might be advised (Yee, 2007).
Research Findings for Sensory Integration
The ongoing interest in sensory integration has resulted in reviews
of its efficacy in several areas and key reviews will now be
synthesized. In examining the application of sensory integration to
individuals with intellectual disability, Arendt et al. (1988a)
described a small and deeply flawed body of research that provided no
empirical support for the continued use of the procedure in clinical
contexts. Hoehn and Baumeister (1994) found similar results in their
review of research on sensory integration with individuals with learning
disabilities. Following analysis of seven outcome studies published
after 1982, they concluded that the "current fund of research
findings may well be sufficient to declare SI therapy as not merely
unproven, but a demonstrably ineffective, primary or adjunctive remedial
treatment for learning disabilities and other disorders" (p. 348).
Sensory issues affecting individuals with autism have been of
interest in recent years and sensory integration has been suggested as a
possible strategy to address these problems (Dawson & Watling,
2000). Dawson and Watling located four relevant studies in their review
and concluded that "these were of such small scale that no firm
conclusions regarding efficacy could be made" (p. 415), although
even this interpretation may have been overly generous (see Goldstein,
2000). In a later review, Baranek (2002) examined only three studies,
identifying important weaknesses in each that made it difficult to
ascribe any observed changes to sensory integration per se.
Baranek's recommendation supporting the cautious use of sensory
integrative therapy seems unjustifiable given the number of studies
examined, acknowledged flaws, and inconsistent treatment effects.
Substantial integrative reviews of intervention options in autism (Lord
& McGee, 2001; New York State Department of Health, 1999; Perry
& Condillac, 2003; Roberts, 2004) have consistently concluded that
there is no credible empirical base to support the application of
sensory integrative therapy Even those recommending the use of sensory
integration in autism (e.g., Baranek, 2002) or suggesting it may have
promise (e.g., Heflin & Simpson, 1998) concede that there is
currently no valid empirical evidence base for the technique.
In addition to descriptive reviews of sensory integration in
specific areas, quantitative meta-analytic syntheses have been
conducted. Ottenbacher (1982) provided a meta-analysis of the small body
of early research on sensory integration, examining eight studies
published prior to 1982. These initial findings were encouraging with an
overall effect size of .79. Unfortunately, this very early promise has
been comprehensively disconfirmed in later and larger analyses. Vargas
and Camilli (1999) provided a meta-analysis of 23 studies comparing
sensory integration to no treatment controls or other interventions.
When compared with no treatment, the mean effect size was .29. While
this was statistically significant, it fell short of the third of a
standard deviation difference that is typically used as the threshold
for educational significance. Vargas and Camilli confirmed the results
of the earlier Ottenbacher meta-analysis but found that effect sizes
fell to .03 in post-1982 studies. When compared with alternative
treatments, the overall effect size was .09, which was not statistically
significant from zero. A similar pattern of results was presented by
Shaw (2002) in summarizing a meta-analysis of 41 sensory integration
studies employing random assignment. Effect sizes for improvement in
language (-.08), behavior (.02) and sensory motor functions (-.10) were
not statistically significant. Small but significant effects were found
for motor skills (.24) and psychoeducational performance (.26) but these
dropped to near zero for studies that controlled for maturation. Sensory
integration is an expensive intervention and available review data
overwhelmingly suggests it is manifestly ineffective.
Sensory integration has sometimes been defended by reversing the
conventional scientific burden of proof. Conventionally, the onus of
proof rests with those proposing an intervention to demonstrate that it
does work. In the case of sensory integration, it is sometimes argued
that critics have failed to demonstrate that it does not work (e.g.,
Ottenbacher, 1988). The end point of this line of reasoning is
demonstrated by Miller (2003) with an argument that amounts to the
justification of continued clinical use of sensory integrative therapy
on the basis of a perceived lack of interpretable scientific evidence.
Indeed, Shaw's (2002) suggestion that sensory integration exhibits
many core features of pseudoscience should not be dismissed lightly.
Despite a consistent lack of supporting evidence, sensory
integration has been highly enduring (Smith et al., 2005). For example,
Green et al. (2006) reported a survey of over 500 parents of children
with autism in which sensory integration was reported as the third most
commonly implemented treatment, ahead of interventions with solid
empirical support such as applied behavior analysis. It is possible that
this resilience may be a product of incorrect perceptions of parents and
educators that sensory integrative therapy may be having an effect.
Mason and Iwata (1990) have clearly demonstrated experimentally that
apparent effects of sensory integrative therapy may be artifacts and
unrelated to the therapy itself. Part of the basis for this resilience
may also relate to the view that research on sensory integration is in
its infancy (Miller, 2003) and that research will eventually catch-up
with professional beliefs (Schaaf & Miller, 2005; Smith et al.,
2005). This would seem increasingly unlikely noting that sensory
integration theory and research now dates back around 40 years. To put
this in context, sensory integration emerged as a field of research at
around the same time as applied behavior analysis. Even if the
contentious argument that sensory integration is unproven rather than
disproved is accepted, the question arises as to whether the public
should continue to be exposed to an unproven intervention?
Tinted Lenses and Overlays
Irlen (1991) reported that during the 1980s she had chanced upon an
amazing discovery when working with adults with reading problems, the
identification of a previously unknown visual-perceptual problem that
interfered with a person's ability to process full spectrum light.
She coined the condition Scotopic Sensitivity Syndrome (SSS), which is
also known as Irlen Syndrome (The Irlen Institute, n.d.) and
Meares-Irlen Syndrome (The Institute of Optometry, n.d.). Some of the
postulated symptoms of SSS included text appearing blurred, spaced as if
a river were running down the page, and letters appearing to swirl or
shake. Irlen theorized that SSS was the reason many people experienced
difficulty in a wide range of important life activities that included
reading, attitude, motivation, self-esteem, depth perception, sports,
movement, coordination, music, math, handwriting, and writing
composition, and claimed that the perceptual difficulties of individuals
with SSS could be ameliorated with the use of colored overlays or tinted
lenses. Unlike the reviews of PMP and sensory integration, the following
discussion is based on primary sources, because there were no
meta-analyses identified in a search of the ERIC, PsychINFO, and MEDLINE
databases between 1990 and 2006.
Description of Practice for Tinted Lenses and Overlays
The use of tinted lenses and overlays has been promoted by two
agencies, the Irlen Institute for Perceptual and Learning Development in
the United States and The Institute of Optometry in the United Kingdom.
It is unclear how widespread the use of tinted lenses is; however, the
Irlen International Newsletter (New Screeners, 2006) listed the
following number of new screeners in various countries: United States,
402; England, 93; Canada, 30; Australia, 24; South Korea, 17; Austria,
8; New Zealand, 5; Hong Kong, 2; Jordan, 2, Slovenia, 1, Switzerland, 1,
Slovenia, 1. The estimated the number of screeners is approximately 7000
worldwide with over 100.000 people using Irlen lenses (Othmer, 2006).
Both organizations claim that colored overlays are effective
treatments for visual-perceptual problems and SSS. They also assert that
the colored overlays must be specifically manufactured and note that
colored overlays purchased from office supply stores would not suffice;
however, they provide no research support for this contention (The
Institute of Optometry, n.d.; The Irlen Institute, n.d.).
The two session assessment conducted by Irlen examiners is only
briefly described in Irlen materials. In the first session, an interview
is conducted, visual-perceptual tasks are administered, and for those
deemed to have SSS, colored overlays are provided. The individual is
told to use the overlays and return for a Tinting Assessment if the use
of colored overlays significantly improved reading. The assessment
conducted by The Institute of Optometry is similar and may include an
eye examination, an interview, and a Colorimetry assessment if
necessary. The Colorimetry assessment is conducted with an Intuitive
Colorimeter, a device developed to prescribe colored overlays and
lenses. However, identification of colored overlays in the studies
reviewed was frequently done through a subjective process of elimination
where subjects were shown various tints and asked to select the best.
Kriss and Evans (2005) noted difficulties with objective assessment of
Irlen syndrome and stated that diagnosis is typically based upon whether
the individual reported immediate improvement or voluntarily used the
overlays for a sustained period of time. While individual reporting may
reflect actual change for the person, reliance on subjective reporting
could be misleading, because an individual may provide a report to
please the investigator, the positive report may be a result of the
placebo effect, or it could represent actual change. It would be
important to clarify this issue in future research using controlled
Research Findings for Tinted Lenses and Overlays
Before reviewing research studies that investigated the use of
colored lenses, a few background issues must be addressed. First,
several researchers have noted the absence of objective scientific
evidence that Scotopic Sensitivity Syndrome actually exists (Blaskey et
al., 1990; Rooney, 1991; Royal College of Ophthalmologists, 2002;
Silver, 1995; Stone & Harris, 1991; Woerz & Maples, 1997).
Second, Irlen and The Institute of Optometry claimed that the symptoms
of SSS are not detectable by standard vision examinations; however,
Solan (1990) and Williams, Kitchener, Press, Scheiman, and Steele (2004)
noted that the identified symptoms of SSS are related to identifiable
vision anomalies. Furthermore, while vision problems must be corrected
so that children can see the printed word, the contention that
neurologically based visual-perceptual problems are one cause of
learning disabilities has not been substantiated (American Academy of
Pediatrics, 1998; Helveston, 1987; Metzger & Werner, 1984). When
considering that SSS is supposedly related to the visual system, it is
of interest to note that the majority of studies reviewed did not
require a vision examination as part of the study. If addressed, most
noted that the subjects had received an exam in the past. For example,
Kriss and Evans (2005) stressed the importance of vision examinations,
but still failed to conduct vision exams prior to conducting their
study. Finally, while both the Irlen Institute and the Institute of
Optometry claim to have unique procedures for diagnosing and
manufacturing the appropriate tint, no research was located comparing
the effectiveness of the different assessment procedures or tints
prescribed by either organization.
In addition to the disagreement regarding the existence of SSS as a
unique perceptual disorder, there is a lack of documentation supporting
the consistency in which individuals select overlays (Fletcher &
Martinez, 1994). Woerz and Maples (1997) conducted a study with 41 high
school students to determine the consistency of student selection of
tinted overlays. In a visual activity in which 24 differently colored
overlays were used, students self-selected the overlay that made the
task easier to complete. Two weeks later, the students were again asked
to select a preferred overlay, and only fourteen students (34%) selected
the same color. When comparing the performance of the 19 students
identified as SSS symptomatic, the results were even worse with only 5
(26%) of 19 choosing the same color on retest. Another study conducted
by Wilkins, Lewis, Smith, Rowland, and Tweedie (2001) examined the
consistency of color selection of 87 students in grades four through six
in one school. They reported that 47% selected the same color on the
second assessment. Unlike Woerz and Maples, they did not report data on
SSS symptomatic students separately.
In spite of the absence of scientific evidence supporting the
existence of SSS or the consistency of colored overlay selection
procedures, a considerable number of studies were conducted to evaluate
the efficacy of colored overlays. In 1990, the Journal of Learning
Disabilities published a special issue that provided intensive coverage
of Irlen lenses. In the preface to the issue, the editor in chief,
Wiederholt, noted that each of the studies had serious theoretical,
medical/physical, and methodological flaws, but were published along
with articles critiquing the studies to provide readers with an overview
of the Irlen procedures as well as guidance for conducting quality
research studies. He, along with Hoyt (1990), Parker (1990), and Solan
(1990), noted that these initial studies by Blaskey et al. (1990),
O'Connor, Sofo, Kendall, and Olsen (1990), and Robinson and Conway
(1990) failed to support the treatment validity of colored overlays.
A brief description of representative studies conducted on both
Irlen and Intuitive overlays is contained in Table 1. The considerable
variability in the findings may be a result of methodological flaws
similar to those identified by Parker (1990). Some of the inadequacies
included: subjective and anecdotal reporting, failure to control for
placebo effect, lack of control groups, failure to determine equivalence
of groups at pre-test phase, use of multiple treatments with one group,
application of multiple statistical analyses without correction for
false positives, failure to control for external threats to validity,
possible experimenter bias, and use of inappropriate measurement
metrics, such as reading age-equivalent scores. Given these concerns
with the research designs, it should not be surprising that there is
considerable variability in findings reported in Table 1.
Some key issues arising from the research on Men overlays will be
discussed followed by a review of research on Intuitive overlays. None
of the studies included a control group who met the criteria for SSS. In
fact, Robinson and Conway (1990) stated, "A control group was not
included, due to the ethical concerns of denying treatment for 1
year" (p. 590). Hoyt (1990) expressed concern that this statement
implied that the researchers were convinced of the validity of Irlen
lenses as a treatment approach prior to conducting the study, which
raised a fundamental concern related to researcher bias. Despite this
concern, future studies by Robinson and Foreman (1999a, 1999b) also
included the same justification for exclusion of a control group with
SSS symptoms. In addition to problems inherent with lack of control,
Robinson and Foreman (1999a, 1999b) subjected two of three experimental
groups to more than one treatment, so any findings for those groups
could not be attributed to a single experimental condition. They also
failed to control for internal and external threats to validity such as
subject maturation or changes in schooling conditions.
Several studies also used inappropriate measurement metrics and
statistical analyses. Reading age was used as a measure of performance
in several studies (Christenson, Griffin, & Taylor, 2001; Martin,
Mackenzie, Lovegrove, & McNicol, 1993; O'Connor et al., 1990;
Robinson & Conway, 1990; Robinson & Foreman, 1999b, Saint-John
& White, 1988). Salvia, Ysseldyke, and Bolt (2007) provided strong
cautions regarding the use of developmental equivalents, such as reading
age, noting that the ordinal nature of these measures precludes their
use in most statistical computations. Other researchers also used
nonstandard measurements in their studies. For example, Lopez, Yolton,
Kohl, Smith, and Saxerud (1994) conducted statistical analyses using
percentile rankings, which were inappropriate for the statistical
analyses conducted. Due to the nature of ordinal scores, the findings in
these studies must be viewed with extreme caution.
In an additional study on Irlen overlays, Whichard, Feller, and
Kastner (2000) evaluated the effectiveness of Irlen overlays on 72
prison inmates. Based on subjective reports from the volunteers, they
determined that the lenses were effective as 40 of the subjects reported
considerable improvement in reading. However, this report cannot be
accepted with any level of confidence as there was no control group and
no objective measure of reading skill before or after selection of
Several studies listed in Table 1 were conducted to evaluate the
effectiveness of the Intuitive colored overlays. As with the studies on
Irlen overlays, the research studies on Intuitive overlays did not
include control groups, did not ensure group equivalence prior to
interventions, and included the use of questionable statistical
procedures. For example, Bouldoukian, Wilkins, and Evans (2002) noted
that some of the subjects had been using overlays for several weeks
prior to participating in that study and approximately one-third had
been performing eye exercises prior to the study. So group equivalence
could not be assumed. In addition, Wilkins et al. (2001) in the third
study reported in that article stated "To save time on testing,
only children who chose an overlay were tested" (p. 55), thus,
there was no comparison group. The statistical analyses were also of
concern and included the use of multiple t-tests without controlling for
Type I error and the use of one-tailed t-tests (Scott et al., 2002;
Wilkins et al., 2001). Both of these procedures increase the chance of
finding a significant difference where one did not exist, thereby,
limiting the confidence that could be afforded to these findings.
In contrast to studies using Irlen lenses, the studies involving
Intuitive overlays tended to demonstrate an increase in reading speed as
measured by the Rate of Reading Test (RRT). Wilkins, Jeanes, Pumfrey,
and Laskier (1996) described the RRT, developed by Wilkins, as a test
that minimized the linguistic aspects of reading by using only 15 common
words and maximized visual difficulties due to spacing, font type, and
font size. They stated that multiple equivalent forms were available but
provided no evidence of alternate form reliability.
A reliability study of the RRT described by Wilkins et al. (1996)
was conducted with 77 students who ranged in age from 8-8 to 11-9 and
were in the fourth, fifth, or sixth grade. No other information
regarding the sample was provided. While they did find an acceptable
correlation, the study was not conducted in the same manner for all
students, which brings into question the level of reliability they
reported. Due to the varied nature of the assessment, the small
experimental group, nonexistent alternate forms reliability measurement,
and limited demographic data, one cannot accept the reliability of the
RRT as presented. In addition to questions about the reliability, there
remain questions regarding the concurrent and predictive validity of the
RRT; perhaps most pressing is whether performance on the RRT is related
to actual reading tasks and school performance. The RRT may in fact be
an acceptable measure of reading speed, and future comparative research
could confirm or disaffirm its use as a reading assessment instrument.
Northway (2003) identified changes in reading rate on the RRT that
were accompanied by large standard errors of measurement. In this study,
subjects who did not choose an overlay actually demonstrated a decrease
in rate of -2.4 words per minute [+ or -] 4, those who chose an overlay
but didn't use it also demonstrated a decrease of -4.4 [+ or -] 9,
and those who reported frequent use of the overlays demonstrated an
increase of 10.2 [+ or -]. 13. In all cases, the standard error of
measure was greater than the change in performance. It is possible that
the large standard error of measure could be related to the use of gain
scores which are not recommended for analyses due to unknown reliability
of gain scores (Thorndike & Dinnel, 2001). Additionally, test
results which demonstrate large standard errors of measure should be
interpreted cautiously because the large error could be due to low
reliability of the measure (Salvia et al., 2007).
In summary, the research conducted on tinted lenses has failed to
demonstrate the efficacy of the practice. The often conflicting findings
between research studies conducted on Irlen lenses with those conducted
on Intuitive lenses may be related to study designs, participants, the
use of different reading assessments, or even the overlays themselves.
The Royal College of Ophthalmologists (2002) noted that the majority of
studies in the literature were poorly designed, but did encourage
controlled research to seriously investigate the issue, as did the
American Optometric Association (Williams et al., 2004). However,
neither organization implicitly recommended the use of colored lenses at
the present time. The American Academy of Pediatrics in a joint
statement with the Committee on Children with Disabilities, the American
Academy of Ophthalmology, and the American Association for Pediatric
Ophthalmology and Strabismus (1998) took a stronger position and firmly
repudiated the use of lenses, stating that there was no scientific
evidence supporting their use. In fact, they noted that the expense of
such treatment is unwarranted and may provide parents and teachers with
a false sense of hope. Following a review of research related to Irlen
lenses, Kavale and Mostert (2004) stated, "Irlen lenses need to
take their place in the history of interventions that have been tried in
the name of special education but failed" (p. 173). Despite these
concerns from noted professional organizations, Kriss and Evans (2005)
stated that many individuals without reading difficulties would benefit
from the use of colored overlays.
This review has focused on three practices that have generated
controversy regarding their efficacy. Research on the oldest of the
three, PMPs has failed to support their use for remediation of academic
difficulties since the original Kavale and Mattson (1983) review, yet
many still persist in various guises. Sensory Integration has been
researched for over 40 years and there has been a failure to provide
convincing evidence suggesting it is effective with any diagnostic
group. The more recent entrant, tinted lenses, shares the same premise
as the older practices: It appears to assume that there is some
underlying deficit in students with disabilities that can be addressed
and that the proposed intervention will lead to improvement in academic
These practices share other common features, such as unique
clinical constructs, terminology, and assessment practices, which have
also been identified as characteristic of other controversial treatments
(Vyse, 2005). The use of clinical constructs, such as Sensory
Integrative Dysfunction, Cerebellar Developmental Delay and Scotopic
Sensitivity Syndrome which are claimed to underlie and "cause"
particular difficulties provides a plausible rationale for the
treatments, but these conditions are not generally recognized outside
the particular controversial practice. For example, none of the
disorders are recognized in DSM-IV-TR (American Psychiatric Association,
2000) and they are not consistent with accepted neurological theory. It
is often specifically argued that sensory integration is consistent with
our understanding of neuroscience (e.g., Dunn, 1988; Heflin &
Simpson, 1998). In reality, however, sensory integration theory is
highly speculative and there are significant reasons to question its
conceptual foundation (see Arendt et al., 1988a; Arendt, MacLean, &
Baumeister, 1988b; Hoehn & Baumeister, 1994; Smith et al., 2005).
Similarly, as has been illustrated in this paper, the conceptual and
theoretical foundations for both PMPs and colored lenses are highly
questionable. The range of symptoms of these disorders casts a broad net
and opposing symptoms may be included (e.g., under- and over-sensitivity
to sensory stimulation for sensory integration) or the conditions, such
as eye fatigue, may be symptomatic of widely recognized visual
disorders. Aligned with these purported conditions are assessment
procedures that may be questionable or subjective, such as the Schilder
test to establish the presence of persistent reflexes in assessment
procedures for some PMPs, postrotary nystagmus in sensory integration
(see Hoehn & Baumeister, 1994) or procedures used to select the
colors of overlays or lenses. These assessment procedures are typically
unique to the specific approach and do not have broader scientific
In the absence of empirical research, proponents rely heavily on
testimonials, anecdotal evidence and in-house unpublished research
studies (see for example, DDAT, n.d.; Irlen Institute, n.d.). The
presentation of anecdote and professional experience in the absence of
scientific evidence (e.g., Evans et al., 1999; Irlen, 1991; Kimball,
1988; Pheloung, 1997) is undoubtedly a factor in the persistence of
these approaches. Reliance on anecdotes and testimonies is recognized as
one of the signs of pseudoscience (Park, 2003) and as a characteristic
of controversial or fad treatments in special education (McWilliam,
1999). A clear belief that personal perceptions are inherently reliable,
even when they are in conflict with objective evidence, is a key feature
of pseudoscientific thinking (Sagan, 1997; Shermer, 1997). The power of
testimonials as persuaders is recognized by the advertising industry
(Cialdini, 2001). Newman (2003) provided some compelling accounts of the
power of personal stories over hard scientific data in the field of
medicine and concluded that a conscious effort is required to make
decisions based on scientific evidence.
Implications for Educators
In the area of education, problems in forming considered judgments
about the relative value of interventions may be exacerbated by teacher
education programs. Postmodernist relativism is common, wherein all
information is considered to simply reflect a particular perspective and
anecdote and opinion is often given the same weighting as controlled
empirical research. Teachers are encouraged through action research
paradigms to appropriately view themselves as active researchers, but
perhaps without understanding the very significant limitations of these
methodologies. There is little doubt that teachers must be taught to be
critical consumers of research but this necessarily involves
understanding what research paradigms are appropriate to what sorts of
questions as well as the limitations of these epistemologies. Mostert
and Crockett (1999-2000) also argue for the inclusion of historical
knowledge about failed or discredited interventions in teacher
education. As we have seen, interventions like PMPs have a long history
and keep reappearing with different names, different rationales but
essentially the same practices.
In order to become informed consumers of research, educators need
to be able to recognize some of the common characteristics of
pseudoscience, as illustrated in the preceding discussion. Warning signs
to the informed consumer may include interventions that are not
consistent with verified theory, that use unique clinical constructs and
assessment practices, and those that rely on anecdotes and testimonials,
particularly in the absence of solid research evidence. Informed
consumers should eschew unproven interventions or those with weak
support in favor of those with more substantive evidence. They also have
a professional responsibility to monitor developments in research, such
that practices can be adjusted to reflect change in the evidence base.
While it is likely to be a thankless task, informed consumers should
also endeavor to educate others about the research base for
interventions, including controversial ones, as well as the principles
of scientific decision making.
Controversial practices are now widely advertised on the internet,
often directly to parents and care-givers - another sign of questionable
science, according to Park (2003) is by-passing peer review and going
straight to the media. Despite lack of data supporting their efficacy,
some controversial programs can involve substantial direct costs. For
example, the Dore program was recently reported to cost around 1,900
pounds or approximately $3,700 US (Nicholls, 2006). Parents will attempt
to search out the most compelling intervention for their child, but are
likely to be uninformed about standards for scientific decision making
and the past history of unproven interventions. Thus, professionals will
undoubtedly encounter situations where parents elect to pursue
ineffective or unproven interventions against advice and sometimes at
great financial cost. One approach to this dilemma may be to agree with
parents on objective expected outcomes, time frames and criteria for
decisions about effectiveness. Smith et al. (2005) provide several
excellent examples of how small n designs can be used to simply monitor
controversial interventions and assist parents in objective and rational
Educators will certainly find themselves in uncomfortable positions
during meetings when practices they know are lacking in empirical
evidence are advocated by other members of the Individualized Education
Program (IEP) team. There is no single or simple response to such a
dilemma, but educators must be prepared to meet the challenge with a
professional demeanor. Some suggestions could include the following.
First, if an educator learns through prior experience in meetings or
just discussion that a professional member of the IEP team will be
recommending a "controversial" practice, the educator could
meet with the other team member prior to the IEP to discuss any concerns
with the "controversial" practice. The discussion may lead to
an agreement to collect data on child progress should the intervention
be implemented, the adoption of a different intervention, or result in a
stalemate. If the discussion results in a stalemate and the
"controversial" practice is ultimately accepted by the IEP
team, then there is a legal obligation to provide the service or
intervention. However, as with all interventions, a careful monitoring
should be conducted to determine the efficacy of the practice, and the
IEP team may even agree to try a practice for a short period of time and
review the data before deciding whether to continue with the
intervention or not. Second, if a practice is clearly not supported by
the research and, after consultation, the provider insists on
recommending the practice at the meeting, the educator could request a
meeting with the service provider and the administrator to discuss the
procedure and determine whether the school administrator would support
that recommendation during an IEP meeting. Third, an educator could also
serve in a problem-solving capacity by identifying exactly what outcome
is to be expected from implementing the specific practice, discuss the
research findings, and suggest other alternatives that hold more promise
in achieving the desired outcome. These recommendations certainly place
a higher level of responsibility on the educator, who must know what may
be recommended at and IEP meeting, whether the practice is supported by
research, and if not, alternatives that would more likely achieve the
It is critical that educators become informed consumers of
research, because school districts must comply with the IEP. Certainly,
administrative support at an IEP meeting can help the district from
agreeing to unnecessary programming, but part of that result requires
that the administrator be educated about the controversial practices.
Educators should be reminded that the law requires the IEP to provide a
student with educational benefit, not maximize a student's
potential. Giangreco (2006) provided useful guidelines for determining
whether a particular related service was required. Since many of the
"controversial" practices will be provided as related
services, his suggestions are useful for determining what must be
provided. First, some IEP team members assume that more service is
better, but this really confuses quantity with quality. Too much of a
service could actually be detrimental, because it could interfere with
the student's participation in school activities with typically
developing peers, result in stigmatization, and create undesired
dependencies on the adults who provide the service or the service
itself. Second, any service should only be as specialized as necessary,
because this approach lends itself to drawing upon natural supports
available to the student and also decreases student dependence on
supports that are not typical of peers without disabilities. Finally,
supports must be educationally relevant and necessary. To be relevant, a
support must be directly linked to educational outcomes, that is, the
goals and objectives on the IEP. If a service is educationally relevant,
then the next question must be whether it is also necessary for the
student to achieve the educational outcomes. If the student is receiving
the desired benefit without the service, then the service would not be
an educational necessity and the school would not have to provide it.
There is a pressing need for a very visible and accessible source
of information on the internet about scientific evaluation of
interventions in special education, similar to the Cochrane
Collaboration in the area of medicine. Such a source could provide
balanced information about effective and controversial interventions and
educate consumers about scientific decision making procedures and the
characteristics of controversial and unproven practices.
In conclusion, there has been a clear shift toward adoption of
evidence-based practice in the area of education in recent years.
Hopefully, more critical thinking and higher standards of evidence will
see a decrease in the use of unproven and disproven interventions, such
as those reviewed in this paper. In order for this to become a reality,
professionals must ensure they are informed about evidence-based
practice and take an active role in disseminating research to consumers.
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Table 1 Summary of Studies on Tinted Overlays
Author(s), Subjects Subject Overlay Eye
Year Ages/Grades Type Exam
Saint-John & 11 with Mean age: Not No
White reading 10-5 Grade: specified
(1988) disability and 6
Blaskey et 30 self Age: 9 to 51 Irlen Yes
al. (1990) referred for years
O'Connor et 92 with Age: 8-12 Not No
al. (1990) reading years Grade: Specified
Robinson & 44 referred to Age: 9-1 to Irlen No
Conway special 15-11 years
Martin et 20 with Age: average Irlen No
al. (1993) reading 12-6 for
disability and those with
SSS, 20 with learning
disability not and 12-5 for
SSS, 20 those
reading Grade: 7
Fletcher & 22 Age: 10 to Irlen No
Martinez 35 years
Lopez et al. 39 from Mean Age: No Irlen Yes
(1994) previous study disability
who had been 11.1;
referred by reading
teachers and general
Robinson & 113 SSS Age: SSS, Irlen No
Foreman referred to 9.2 to 13.1;
(1999a) special non SSS, 9.4
education to 12.9
Robinson & 113 SSS Age: SSS, Irlen No
Foreman referred to 9.2 to 13.1;
(1999b) special non SSS, 9.4
education to 12.9
Whichard et 72 prison Age: 16 to Irlen No
al. (2000) volunteers 67
Christenson 16 with Age: 10-6 to Not Yes
et al. learning 13-11 Grade: specified,
(2001) disability 5 to 8 blue
Wilkins et 89 students in Age: 8-6 to Intuitive No
al. (2001) one school 10-6 Grade:
Study 1 4 to 6
Wilkins et 378 students Age: 8-2 to Intuitive No
al. (2001) in one school 12-1
Bouldoukian 33 patients Age: 1-10 to Intuitive Yes
et al. attending 40
(2002) Institute of
Scott et al. 153 students Age: 10 to Intuitive Yes,
(2002) Study in one school 12 after
Scott et al. 199 students Age: 7 to Intuitive Yes,
(2002) Study in one school 11 after
Northway 60 children Age: Not Intuitive Yes
(2003) who attended specified
an eye clinic Grade: Not
for 6 months Specified
Author(s), Measures Findings related to academics
Year and overlay
Saint-John & 1) Reading rate in No difference on later
White identification or reading speed
2) Errors in letter
Blaskey et 1) Standard scores No improvement in reading speed,
al. (1990) word recognition, or
2) Scaled scores
3) Reading speed
O'Connor et 1) Reading age Improved reading rate, accuracy,
al. (1990) and comprehension when using
preferred color lens
Robinson & 1) Reading age Improvement in comprehension and
Conway accuracy but not rate
Martin et 1) Reading age No effect on accuracy,
al. (1993) comprehension, encoding
2) Reading rate
Fletcher & 1) Comprehension No effect on comprehension
Lopez et al. 1) Mean age No relationship between SSS and
(1994) academic achievement
2) Mean grade
3) Percentile Score
Robinson & 1) Reading miscue No impact
Robinson & 1) Reading age Improvement in accuracy and
Foreman comprehension but not rate
Whichard et 1) questionnaire 55.6% reported improvement
Christenson 1) Grade equivalent No change in comprehension or
et al. reading rate
2) Time to complete
Wilkins et 1) reading rate Improved rate
Wilkins et 1) reading rate Improved rate for chosen color
Bouldoukian 1) reading rate Improved rate for chosen color
Scott et al. 1) reading rate Improved rate for frequent use
Scott et al. 1) reading rate Improved
Northway 1) reading rate Improved for group choosing color,
(2003) but decreased for group who chose
but didn't use overlay, and
decreased for group who did not
choose an overlay