New York, Feb 4 (IANS): For most adults and older children it's a simple and easy concept to rate their pain on a scale of 10. But children under the age five generally lack the intellectual skills required to report the intensity of their pain, a new study reveals.

"Using a scale to estimate and report pain intensity is a complex mental process and is often challenging for children under the age of five or six," the researchers wrote in the research published in the journal, PAIN.

The study discussed cognitive (intellectual) development issues affecting children's ability to rate their pain and modifications for more developmentally appropriate pain assessments in the preschool age group.

Children below five years of age may "report their pain in idiosyncratic ways that appear inappropriate for the context", the researchers stated.

Factors like memory of pain and knowledge of magnitude and symbolic processing limit preschoolers' ability to make pain self-assessments.

The study showed, words used to describe pain -- such as "ow" or "hurt" -- emerge as early as 18 months of age, and toddlers can point to a part of their body that hurts.

By three years, most children have basic pain vocabulary. But it's not until age five that most children can "accurately describe concrete causes, perceptions, and intensity of pain", according to the authors.

The cognitive process of explicit memory is influenced by language ability and social interactions reflect. For example, children look to their parents to assess whether a painful event is trivial or threatening, the study found.

Past pain experience also plays a role -- preschoolers who have undergone surgery make pain intensity ratings more similar to those of older children.

As with numerical scales, the typical five-year-old has the skills to use these alternative tools while most three-year-olds do not, the researchers noted.