Abstract
Forty male volunteers were randomly assigned to one of four experimental groups (Ns = 10) which received 10, 15, 20, or 25 g, under abrupt deceleration conditions at the end of a 120-ft. sled run. Ss were not aware beforehand of their preassigned groups. A battery of tests, including the Graham-Kendall MFD test was administered to each S during an initial testing period under normal test conditions. About 1 mo. later, each experimental S was given a three-test battery, including the MFD, prior to the sled run (pre-stress period) and about 25 min. after experiencing impact (post-stress period). The same battery of tests was administered to a control group (N = 10) at times comparable to those for the experimental groups, but the control group was tested at all times under standard testing conditions. The mean height of the 15 MFD drawings was analyzed for each S for each group at the three periods. This analysis supported the hypothesis that, although the control group showed essentially no change in height of drawings over the three trials, the experimental groups exhibited a significant decrease (p < .01) in height of drawings during the pre-stress period. The decrease in drawing size was not a function of the number of g experienced but seemed to be a result of the anticipated stress.