An Apparatus for Measuring Operational Hand Steadiness

THE JOURNAL OP APPLIED PSYCHOLOGY Vol. 37, No. 1, 1953

An Apparatus for Measuring Operational Hand Steadiness

J. Stanley Gray, George Sustare, and Anthony Thompson University of Georgia

It is a patent belief of both job analysts and skilled workmen that the degree of skill is affected by hand steadiness. This study is an attempt to investigate that belief.

Available apparatus for measuring hand steadiness (like the Whipple Tracing Board) was found to measure predominately static steadiness’or tremor. Skilled work involves operational steadiness. Consequently, an ap- paratus was devised to measure hand steadi- ness in three dimensions. This stasiometer consists of a 24″ X 30″ base on which are mounted the ends of seven feet of %-inch copper tubing bent in three dimensions, an electric counter, a transformer, and a knife switch. A brass stylus-ring, through which the tubing passes, is connected to one terminal of the transformer and the copper tubing to the other through the counter. Contact be- tween the stylus-ring and the tube activates the counter. See Figure 1 for schema.

FIG, 1. Schematic diagram of stasiometer.

A test run consists of passing the stylus- ring along the bent tubing from one end to the other and back again as rapidly as possible with the least number of contacts. After a practice training run, the time in seconds and

the contacts (as recorded by the counter) are recorded for two runs, or four crossings. A minute rest is allowed between these two re- corded runs.

Table 1

Mean Time and Contacts for Two Runs on the Stasiometer

Mean S.D.

First Run Time (Sec.) Contacts

Second Run Time (Sec.) Contacts

80.9 115.0

78.9 107.2

31.7 34.9

29.6 35.3

The test was administered to a norm group of 400 undergraduate university students (222 men and 178 women). The mean time and mean contacts for each of two runs are shown in Table 1. A table of sigma values was then constructed and each raw score was converted into a Z score (mean 100, sigma 30). A Z score was thus obtained for each run (time plus contacts). The coefficient of correlation between these runs was .84 ±.01, which was interpreted to indicate a satisfactory reliabil- ity.

The Z scores for each run were then added to obtain a total steadiness test score. The distribution of the 400 norm cases is shown in Figure 2.

Various factors which might affect steadi- ness were studied but only two showed any statistical significance. Sex was a highly sig- nificant factor, the men having 10 Z-score points higher than the women. Smoking had only a slightly significant effect on steadiness, as indicated in Table 2.

A total of 100 members of the norm group was given the Edwards’ finger tremor test.1

The coefficient of correlation was .004, indicat- 1 Edwards, A. S. The finger tromometer. Amer.

J. Psychol, 1946, 59, 273-283.

57

58 /. Stanley Gray, George Sustare, and Anthony Thompson

24- 36- 48- 60- 72- 84- 96- 108- IZO-132- 144- 35 47 59 71 83 95 107 119 131 143 155

FIG. 2. Distribution of 400 standard scores on the stasiometer.

ing that hand operational steadiness and hand static steadiness are not related.

Another group of SO subjects was given the Purdue Pegboard dexterity test. The correla- tion of these scores with those on the stasi- ometer was .057.

The stasiometer test was given to 50 skilled workmen (tool and dye makers, machinists,

Table 2

The Effects of Smoking and Sex on Operational Hand Steadiness

Smokers Non Smokers

Male Female

N

225 175

222 178

Mean Steadiness Z Score

101.9 99.2

105.1 95.1

S.D.

20.3 21.5

19.2 21.3

C.R.

49

sheet metal workers, and welding inspectors). The average Z score for this group was 121.5, S.D. 16.7, as compared with a mean of 100 and S.D. of 30 for the norm group. The CR of the difference between these averages was 7.6. Further validity data are being collected.

Apparently the stasiometer is a reliable in- strument for measuring operational steadiness and it may have some usefulness in selecting apprentices for various skilled occupations.

Received April 17, 1952.

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