Truth in Advertising Claim

ISSUE

A writing instrument manufacturer (A) claimed to reduce writing stress by a certain percentage.

METHOD

One of their competitors (B) did not believe the claims and asked for an experiment to be conducted to determine what, if any, writing stress levels were induced. First writing stress had to be defined quantitatively as this was missing on their packaging and as part of the discover process scientific papers were produced which allowed us to define writing stress. Writing stress was defined by a number of measures, but one of the most important was the ratio of pen point stress, the amount of pressure one exerts on a writing surface, to the amount of muscle activity, as measured by surface electromyography (semg) required to exert that force. In addition and as a control measure a goniometer that measures wrist joint motion was utilized to ensure that wrist motions between trials were similar. Six (6) different writing instruments were tested including the one by (A) and one by (B). The order of pen testing was randomized. A piece of cardboard that was the same thickness of the pressure sensing surfaces was utilized and it was cut out so that these sensing surfaces could be embedded in the cardboard and then covered with two sheets of paper to hide their location from the subjects. Each subject had to write a standard paragraph in script on a piece of paper that was placed on top of these two pieces of paper and the cardboard with embedded pressure sensors. Each subjects writing hand had an electric goniometer on the wrist joint as well as (semg) sensors for the thumb, finger and wrist muscles. This allowed us to measure muscle activity as a ratio to pen point pressure at multiple locations on the paper. An equal number of men and woman with no pre-existing upper extremity musculoskeletal disorder participated in the study.