Heimstra Human Factors Laboratory

Pilot Study

Characteristics of the Golden Grip knife with Thumbgrip handle

December 5, 2004

By

Kevin Limrick

klimrick@usd.edu

Abstract

Subjects were asked to evaluate the comfort and mechanical characteristics of a new knife handle. Each subject was asked to perform cutting tasks and rate their perceptions. The Golden Grip knife with Thumbgrip handle appears to provide more comfort and more blade control. An in depth study has been requested.

Methodology

This pilot study was small in scale (only 5 subjects), yet we yielded some very promising results. Essentially we had each subject cut pieces of a clay-like substance using either the ergo knife or a standard kitchen knife. We measured individual differences, such as hand strength, hand width, and hand length, as well as performance measures such as how many slices each person could cut in one minute, and the force they exerted while cutting. We also gave each subject a questionnaire to fill out in regards to: the comfort level of the grip on the knife they were using, and how much control they felt they had over the blade they were using. We also asked them to subjectively assess (on a scale from 1-7) how much stress they felt on their forearm and hand during the cutting process. Below is a table of the results from this pilot study:

Subjective Assessment: Rating Scale

Scale from 1 to 7 (1 = worst, 7 = best)

Subject Questionnaire:

1.) Rate the stress felt in your hand

2.) Rate the stress felt in your forearm

3.) Rate how comfortable this grip is

4.) How easy was the blade to control

Overall Findings:

	Ergo Knife (variable)	Standard Knife (control)	Ergo Knife Difference (effect)
Force (lbs.)	10.0	16.1	6.1 lbs less force to cut
Slices / min.	9.4	8.3	1.1 more slices per minute
Stress (hand)	5.0	2.3	2.7 increased hand comfort
Stress (forearm)	5.0	2.5	2.5 increased forearm comfort
Grip Comfort	5.7	3.0	2.7 increased grip comfort
Blade Control	5.8	3.2	1.8 increased blade control

Discussion

As noted previously, the results look promising, however as I am sure Dr. Berkhout as mentioned we are planning on taking this a few steps further. Firstly we will need to evaluate comparable blades set in comparable (as close as possible) handles. We will also want to quantify stress levels in the hand and forearm by use of an electromyograph. At this point, we have completed the necessary paperwork needed to begin a full study of this product. This next potential study will need to be reviewed and approved by the Human Subjects Committee here at USD but barring any unforeseen obstacles we will begin a larger study of this product once approval has been given. If you have any further questions, feel free to email myself or Dr. Berkhout.