Preliminary study of dial reading performance during sustained acceleration and vibration. AMRL-TR-65-110.

Boo s ter induc ed spac e raft v ibrations o c cur in combination w i th booster induced sustained a cceleration. This was a joint NASA-AF study to provide a preliminary c rsory evaluation of the effects of this env ironment on crewmen. S i x subjects were used in 60 tests to measure the d ecrement in dial reading ability as a function of the level of 11 cps g x v ibration aud the size of the dial, where a bias acceleration of 3. 85 Gx as superim osed on th e vibration. Dial reading errors were inv ersely r ela ted to the arc leng th of the interv al between dials and d i re c tly related to the amplitude of v ibra t ion. There was ap:'roximately 50% distor tion of the 11 cps v ibration accele r a tion, which markedly infl uences the inte1 pretation of results and their om parison to measurements of visual decrement s f rom 1 1 c ps v ibrations with IG bias loads. In most general terms, howev er, the 3. 85Gx bias, and/ o r ~e unidirectional force (i.e., the res ultant a cce l e ration was always r eater than 0 G creates a subjectiv ely more tolera bl e environment than with a 1 G bias. Vibrations of 3. 85Gx ± 3. Og x were without serious s ubjective effects in exposures of 90 seconds duration. Gr o s ompari s ons of dial r eading performance under the two condi tions provid some indication tha t th e g reater bias a c ce leration i s a ssoc i a ted with les s v isual de c rement.