HUMAN BEHAVIOR PROGRAM 



261 



that there was no mental deterioration during Sealab, but only that, if there was any, it was not 

 gross enough to be detected by this test. 



Visual Studies 



Form/Color Test — It will be recalled that the purpose of this test was to measure detec- 

 tion and discrimination of form and color underwater. Six divers were used to obtain a total of 

 20 observations on each of the four targets. Table 30 shows the mean detection and recognition 

 distances. 



Table 30 



DETECTION AND RECOGNITION DISTANCES 



FOR THE FORM/COLOR STUDY 



(N = 20) 



It is readily apparent that the black circle is both detected and identified at greater dis- 

 tances than either the white or yellow targets. This is particularly interesting when consider- 

 ing that it is the smallest of the four targets in area (black disc = 707 sq cm, white targets = 

 900 sq cm). The differences between the means of the black circle and the white square were 

 tested using the standard t-test and found to be significant at better than the 0.01 level of con- 

 fidence. The mean detection and recognition distances of the white cross and yellow triangle 

 are even less than the white square. 



When one considers that visibility is a function of contrast between target and background, 

 it becomes clear that the contrast of the black circle was greater under the conditions sur- 

 rounding Sealab. 



General Visibility Observations —A major factor in underwater operations is visibility. 

 The selection of the Sealab site was, in fact, almost changed at the last minute because of poor 

 visibility. Although the experiments on underwater light visibility were not carried out as 

 planned, some data were obtained during the debriefing interviews. Each diver was asked to 

 estimate the maximum distance he could see a 1000-watt underwater quartz light. For Team 1 

 the mean answer of nine responses was 43 ft, with a range of 30 to 60 ft. For Team 2 the mean 

 answer was 60 ft, with a range of 50 to 70 ft. Team 3 had a mean of 95 ft and a range of 40 to 

 170 ft. It is apparent that the general visibility was improving during the 45-day submersion 

 period. 



Data were collected with the water-clarity meter during Teams 2 and 3 dives, which hope- 

 fully can be related to the daily reports of visibility recorded on the sortie report form. 



All 28 divers stated that the white habitat was far more visible than the reddish-orange 

 personnel transfer capsule (PTC) sitting on the bottom 15 ft away. In many cases the habitat 

 was said to be visible at two or three times the distance of the PTC. 



Further studies need to be performed on underwater visibility of light and color. It must 

 be kept in mind that studies in fresh water and even at shallow depths in the ocean cannot nec- 

 essarily be extrapolated to greater depths. This is particularly true when selecting paint and 

 coding colors. 



