Yes, most of the papers listed do mention children and arithmetic. This is probably due to the fact that higher forms of math have a foundation in the basic mathematical functions used in arithmetic. Also, learning disabilities are usually easier to determine and clarify in children. Most adults, who may have a learning disability but were never diagnosed with it, usually will develop compensatory behaviour that may affect experiments trying to quantify a disability.
National Center for Learning Disabilities website on Dyscalculia
http://www.ncld.org/index.php?option...sk=view&id=463
From the above link...
Dyscalculia is a term referring to a wide range of
life-long learning disabilities involving math. There is no single form of math disability, and
difficulties vary from person to person and affect people differently in school and throughout life.