HUMAN BEHAVIOR PROGRAM 247 



The test utilized two calibrated torque wrenches, one with a scale from to 800 lb, the other 

 with a scale from to 1200 lb. Two strength tests were used; the lift test, and the pull test. 

 The lift test consisted of bracing the feet on a platform and lifting upwards on a handle posi- 

 tioned about 30 in. above the platform. The pull test was carried out by grasping the handle 

 with the left hand at about shoulder height, while simultaneously grasping a grip with the right 

 hand (Fig. 101). By adjusting the right-hand grip, each man could achieve a full arm-stretch 

 position. In both tests, the subjects were told to exert maximum force. The torque achieved 

 was recorded by a deflexion arm which moved a recording marker along a scale. 



Fig. 101. Diver performing 

 strength test in shallow water 



These tests were chosen because they are representative of the actions required when 

 divers are used as primary power sources, and because they provide data that are directly 

 applicable to the design of hand tools. In addition, it was expected that the forces recorded in 

 the lift test would be two to three times those recorded in the pull test, thus giving an appreci- 

 able range in terms of muscle activity. 



Individual Assembly Test — This test measured manual dexterity and the ability to form 

 spatial relationships. The test required the diver to assemble three one-foot lengths of steel 

 plates into a triangle by joining the corners of the plates together with nuts, washers, and bolts. 

 The divers were required to assemble each corner by placing a washer on each side of two 

 lengths, pushing a bolt through the four pieces, and securing the whole assembly by screwing 

 on a nut. Two bolt sizes were used: 5/32 and 5/8 in. The holes at the ends of the plates were 

 placed either symmetrically (same corners), so that any end would fit to any other end, or 

 asymmetrically (different corners), so that the end of one length would fit only to one end of 

 one of the other two lengths. The combination of the bolt size and symmetry variables resulted 

 in four forms of the test. While it was possible to assemble the symmetrical plates in any 

 combination, only one manner of assembly resulted in the exact superimposition of two lengths 

 at each corner. Thus, the four versions of the test varied the challenge to the subject in terms 

 of the degree of fingertip dexterity required, as well as his ability to form spatial relationships. 

 Performance in the water was expected to deteriorate as compared to dry-land conditions, due 

 to the cold, the wearing of gloves, etc. In addition, one might expect performance to decrease 

 as a result of poor visibility and general problems associated with maintaining body orientation 

 with respect to work components. The test was selected as being representative of tasks re- 

 quiring the assembly, adjustment, and general handling of small items of equipment. 



