Review included studies that evaluate the effects of linguistic comprehension interventions on generalized language and reading outcomes

Complete report

The linguistic comprehension programs included in this review display a small positive immediate effect on generalized outcomes of linguistic comprehension. The effect of the programs on generalized measures of reading comprehension is negligible. Few studies report follow‐up assessment of their participants.

1.2 What is this review about?

Children who begin school with proficient language skills are more likely to develop adequate reading comprehension abilities and achieve academic success than children who struggle with poor language skills in their early years. Individual language difficulties, environmental factors related to socioeconomic status (SES), and having the educational language as a second language are all considered risk factors for language and literacy failure.
Intervention programs have been designed with the aim of supporting at‐risk children's language skills. In these programs, the instructional methods typically include a strong focus on vocabulary instruction within the context of storytelling or text reading. Elements that directly activate narrative and grammatical development are often included.

What is the aim of this review?
This Campbell systematic review examines the effects of linguistic comprehension instruction on generalized measures of language and reading comprehension skills. The review summarizes evidence from 43 studies, including samples of both preschool and school‐aged participants.

1.3 What studies are included in this review?

This review included studies that evaluate the effects of linguistic comprehension interventions on generalized language and reading outcomes. A total of 43 studies were identified and included in the final analysis. The studies span the period 1992–2017. Randomized controlled trials (RCTs) and quasi‐experiments (QEs) with a control group and a pre–post design were included in the review.

1.4 What are the main findings of this review?

The effect of linguistic comprehension instruction on generalized outcomes of linguistic comprehension skills is small in studies of both the overall immediate and follow‐up effects. Analysis of differential language outcomes shows small effects on vocabulary and grammatical knowledge and moderate effects on narrative and listening comprehension.
Linguistic comprehension instruction has no immediate effects on generalized outcomes of reading comprehension. Only a few studies have reported follow‐up effects on reading comprehension skills, with divergent findings.

1.5 What do the findings of this review mean?

Linguistic comprehension instruction has the potential to increase children's general linguistic comprehension skills. However, there is variability in effects related to the type of outcome measure that is used to examine the effect of such instruction on linguistic comprehension skills.
One of the overall aims of linguistic comprehension intervention programs is to accelerate children's vocabulary development. Our results indicated that the type of intervention program included in this review might be insufficient to accelerate children's vocabulary development and, thus, to close the vocabulary gap among children.
Further, the absence of an immediate effect of intervention programs on reading comprehension outcomes indicates that linguistic comprehension instruction through the type of intervention program examined in this study does not transfer beyond what is learned to general types of text. Despite clear indications from longitudinal studies that linguistic comprehension plays a vital role in the development of reading comprehension, only a few intervention studies have produced immediate and follow‐up effects on generalized outcomes of reading comprehension. This indicates that preventing and remediating reading comprehension difficulties likely requires long‐term educational efforts.
Finally, it is likely that other outcome measures that are more closely aligned with the targeted intervention (use of targeted instructed words in the texts) would yield a different pattern of results. However, such tests were not included in this review.