Review of “Ethnic Variables in Human Factors Engineering. Edited ” by Alphonse ChApanis-(Baltimore: Johns Hopkins University Press, 1975.) [Pp. xviii + 290.] £9-50.

Measurements were made of the motion of a ship, and of the consequent seasickness experienced by passengers. Data are presented for 17 voyages of up to 6?hours duration, involving 4915 passengers. Vertical motion occurred up to 1·0 m s^?2 r.m.s. and vomiting incidence of up to nearly 40% was encountered.

Both vomiting incidence and illness rating correlated well with root mean square vertical z-axis acceleration. The effect of exposure duration was also investigated, producing suggestions for a combined measure of acceleration and time. Multiple regression analysis with all six axes of motion revealed only a small increase in correlation when all directions of motion in addition to the z-axis were taken into account.     

Review of: “Handbook of Psychophysiology. Edited by Norman S. Greenfield and Richard A. Sternbach.” (New York: Holt,Rinehart and Winston, 1972.) [Pp. xii-f-1011.] £14-30.

The purpose of this study was to assess the effects of hip belt use and load placement in a backpack on perceived exertion and postural stability. Thirty participants were instructed to stand on a force plate and walk along a designated route under five conditions: unloaded, high-load placement, low-load placement, hip belt on and hip belt off. The average velocity and sway area from the force plate were measured. Participants also rated their perceived stability and exertion. Compared to the unloaded condition, all loaded conditions significantly increased average velocity, sway area, perceived stability and exertion. Hip belt use did not affect average velocity and sway area; however, participants reported higher levels of stability and lower levels of exertion with hip belt use. Load placement did not affect average velocity, sway area, perceived stability or exertion. This study showed that wearing a backpack loaded to 20% of body weight reduced postural stability, while manipulation of load placement in a backpack did not affect subjective and objective measures of postural stability. Also, hip belt use only improved subjective measures of postural stability.     

Review of: “The Computer in Psychology”, Edited by Michael J. After and George Westby. (London: Wiley, 1973.) [Pp. xvi+309.] £5.50.

The purpose of this study was to investigate the effects of drop height in the performance of plyometric training. Thirty male subjects were asked to perform drop jumps from heights of 012, 0-24, 0-36, 0-46, 0-58, and 0-68 m, as well as counter-movement jumps and squat jumps. They performed their jumps on a Kistler force platform, and the resultant force trace was integrated to calculate negative displacement of the total body centre of gravity (CG), net height rise of the CG, maximum vertical force, maximum vertical velocity, and peak instantaneous power output derived from the product of force and velocity. The results showed that the best performance in all measured parameters was for the drop height of 0-12 m. This finding differed from results of similar studies reported in the literature by others (Asmussen and Bonde-Petersen 1974, Bosco and Komi 1978). This finding was interpreted in terms of a skill and co-ordination element in the performance of plyometric movements, in contrast to a natural biomechanical response to imposed load, and the state of muscle training and competency.