Abstract： Objective To investigate the effects of 2.0 MPa heliox exposure on the rate of information processing,endogenous attention and spatial working memory of divers.Methods Four divers participated in the study.Tests were made on the performance of simple reaction time,selection reaction time,discrimination reaction time,endogenous attention and spatial working memory both before and after pressure exposures,as well as compression to a pressure of 2.0 MPa,and differences in the above indicators were compared between them.Results There were no significant differences in simple reaction time,when comparisons were made between pre-exposure,2.0 MPa pressure exposure and post-exposure.But statistical significance could be noticed in selective reaction time [(418.560 ± 13.932) ms,(473.080 ± 34.154) ms and (442.410 ± 15.184) ms respectively],when comparisons were made between pre-exposure,2.0 MPa pressure exposure and post-exposure(F =5.539,P ＜ 0.05).Statistical significance could also be seen in discrimination reaction time (307.395 ± 3.531,358.740 ±12.536,319.145 ± 2.037,respectively),when comparisons were made under the above-mentioned 3 different situations(F =11.433,P ＜ 0.01).Before exposure,during exposure at 2.0 MPa and after exposure,endogenous attention reaction time of the divers was respectively [(138.199 ± 2.028) ms,(156.914 ± 3.247) ms and (143.958 ± 3.050) ms,and statistical significance was shown,when comparisons were made between them(F =12.913,P ＜0.01).Under the above 3 situations,spatial working memory reaction time was respectively (493.572 ± 83.412) ms,(550.280 ± 86.815) ms and (523.658 ± 78.797) ms,and statistical significance was also be seen,when comparisons were made between them(F =15.255,P ＜0.01).Conclusions 2.0 MPa heliox exposure seemed to affect the divers in the processing of complicated tasks,which might be associated with the impairment of divers in attention selection and information storage encountered during helium exposure.