Lewandowski, L. J., Lovett, B. J., Parolin, R., Gordon, M., & Codding, R. S. (2007). Extended time accommodations and the mathematics performance of students with and without ADHD . Journal of Psychoeducational Assessment , 25 (1), 17–28. https://doi.org/10.1177/0734282906291961

The effects of an extended-time (time and one-half) accommodation on a mathematics test were investigated.

A total of 54 students in grades 5, 6, and 7 from three school districts in central and eastern New York State (U.S.) participated. One-half of the students had attention-deficit hyperactivity disorder (ADHD), and one-half did not have disabilities.

The dependent variable was number correct on a mathematics calculation test (MCT) especially developed for this study which consisted of calculating 540 three-digit by three-digit addition problems. Additional data were gathered through the Processing Speed index of the Wechsler Intelligence Scale for Children, Fourth Edition (WISC-IV); Mathematics Fluency subtest of the Woodcock-Johnson Tests of Achievement, Third Edition (WJ-III); the home form of the ADHD Symptom Rating Scale (ADHDRS); and the parent form of the Behavior Rating Inventory of Executive Function (BRIEF); as well as a basic demographic survey.

The results did not support the differential boost hypothesis in that the ADHD group did not make more gains than the control group with extended- time. However, the ADHD group did demonstrate lower processing speed, math fluency, and achievement. These findings suggest that, although students with ADHD tend to work with less overall efficiency in terms of processing speed and task fluency, they do not benefit significantly more than non-disabled students when given extended-time on a speed-based math task. Limitations of the study were reported.