executive summary was written by AIR personnel and reflects the
work of the following research report.
Research for Students with Learning Disabilities: A Meta-Analysis
of Treatment Outcomes
Author: Dr. H. Lee Swanson, University of California - Riverside
the last 20 years, the number of children classified as having
learning disabilities has increased substantially, from roughly
three-quarters of a million in 1976 to more than 2.6 million in
1997. These children currently make up almost half of schools'
special education population, yet it is still unclear which teaching
strategies best help these children. Furthermore, a review of
past literature reveals few systematic analyses of instructional
approaches for students who have learning disabilities. This lack
of clear direction creates confusion about how best to educate
students with learning disabilities are a heterogeneous group
and no general or single intervention can be recommended
for these students. However, this report can offer recommendations
from its investigation of evidence derived from many different
studies on teaching students with learning disabilities. In this
meta-analysis we synthesize research on the effects of various
forms of instruction intended to improve students' academics (e.g.,
reading, mathematics), cognition (e.g., problem solving), or behavior
(e.g., social skills). For the most part, the interventions and
instructional methods that are discussed in the report begin one
to two years after school entry and continue throughout the student's
middle and highschool education.
meta-analysis includes 272 studies, which met four criteria. Each
study had to:
learning-disabled students of average intelligence who were
assigned to an experimental or a control instructional condition.
information on how students with learning disabilities were
no severe flaws.
analyzed the effects for a range of studies that included both
studies of a single area and studies that examined a mix of subjects
across the following: instructional domains (e.g., reading, mathematics);
sample characteristics (e.g., age, intelligence); intervention
parameters (e.g., number of instructional sessions); and methodologies.
synthesis examines research conducted over the last 30 years produced
several findings related to intervention for students with learning
disabilities. Unless otherwise noted, these findings come primarily
from the group-design studies.
forms of instruction were most effective?
most effective form of teaching children with learning disabilities
combined components of direct instruction (teacher-directed
lecture, discussion, and learning from books) with components
of strategy instruction (teaching ways to learn such as memorization
techniques and study skills). The main instructional components
of this combined model include:
these components, the one most linked to effect on student
achievement was control of task difficulty (where, for example,
the teacher provided necessary assistance or sequenced tasks
from easy to difficult.) Another influential component was
the use of small interactive groups of five or fewer students.
A third strongly influential component was the use of structured
questioning and directed responses, involving, for example,
interactive questions and answers or the teacher directing
students to ask questions and summarize.
with learning disabilities perform closer to nondisabled (age-related
peers) children on reading outcome measures when treatment
includes strategy instruction. Not surprisingly, nondisabled
students generally outperform learning-disabled students.
However, there was less difference between the performance
of the two groups when learning-disabled students were exposed
to treatments that included strategy instruction compared
to competing treatments like Direct Instruction.
the area of reading, both phonics and whole word (whole language)
instruction make a significant contribution to student achievement
in reading. Neither clearly supersedes the other in terms
of transfer measures (reading real words and comprehending
text). However, while phonics instruction is an aspect of
beginning reading instruction, whole language instruction
is broader and can be applied throughout the elementary school
a few instructional components successfully predict effects
on student achievement. Although several instructional components
seem to produce effects when studied independently (e.g.,
segmentation predicts outcomes on phonological measures),
the results vary more widely when instruction reflects the
variance shared across components. This happens because individual
strategies typically do not appear in isolation in a classroom,
and often their importance as predictors is enhanced in the
context of other components.
subject areas were most affected by different instructional strategies?
studies in the areas of reading comprehension, vocabulary,
and creativity met our threshold for having a large effect
(when adjusted for differences in how the studies were conducted.)
We found moderate effects in the areas of cognitive processing
(e.g., problem solving), word recognition, memory, writing,
intelligence (e.g., performance on standardized tests), attitude/self-concept,
phonics/orthographic skills (e.g., recognizing correct spelling),
and global achievement (e.g., teacher grades, class ranking).
Relatively weak effects were found in the areas of spelling,
mathematics, general reading, social skills, perceptual-motor
processes (e.g., handwriting), and language processes (e.g.,
listening comprehension). However, single subject design studies
found large effects in all subjects except for handwriting.
effects are specific to the academic problems being addressed.
If you look across academic subjects, the most effective model
was a combination of direct instruction and strategy instruction.
However, its effect was greater in reading than in non-reading
measures, such as mathematics and social skills. Within the
field of reading, this model is particularly effective for
reading comprehension compared to recognition. We also found
that bottom-up instruction (direct instruction only) was more
effective than top-down instruction (strategy instruction
only) on word recognition, but not on reading comprehension.
other factors influence achievement?
ways of identifying whether a child has learning disabilities
or not (using either cut-off scores in tests or variation
between student achievement and that predicted by an IQ test)
will affect achievement outcomes. The results suggest that
studies that used a cutoff score criteria (at or above 84
and reading scores below the 25th percentile) found smaller
effects from the treatment. For both group and single-subject
design studies, the model combining direct and strategic instruction
yielded higher effect sizes when cutoff scores can be computed
than when they cannot. For single-subject design studies,
the combined model yields higher effect sizes for the lower
IQ discrepancy studies when compared to those studies that
report discrepancies, but with relatively higher IQ scores.
variations in how the studies were conducted can have a significant
impact on treatment outcomes. Studies that account for differences
from the control (non-treatment) condition in terms of setting
(classroom and school), teacher, and number of instructional
steps yield larger effects than studies that fail to control
for such variations. A serious threat to interpreting treatment
effects are studies that unfairly "stacked" the treatment
condition with substantially more steps and procedures than
the control condition. Here, although it was clear that how
the study was conducted did have a strong influence on its
findings, researchers found that there were still significant
effects related to various types of treatment, even with controls
for the methodological factors.
should investigate which treatment approaches are most effective
and the causal processes by which they work. They also should
pay attention to the interactions of instruction and learning
should combine direct instruction with strategy instruction.
They should focus on task difficulty, small interactive groups,
and structured questioning and directed responses.
should match instructional techniques to the subject areas
in which they are most effective. For example, reading comprehension
should be taught with a combination of direct instruction
and strategy instruction. Bottom-up instruction can be used
for word recognition but not reading comprehension. Both phonics
and whole word methods (whole language) should be used to