The hypoxia threshold for a decrement in perceptual-motor performance was determined with six subjects using a serial choice response time task at two levels of stimulus brightness. Low-oxygen mixtures were used to reduce SaO] (arterial oxyhemoglobin saturation) to hypoxic levels ranging from 86% to 76% in steps of2%. These values correspond to altitudes ranging from 8900 ft to 11 400 feet. Response time was slowed in a dose-dependent manner with a significant effect becoming apparent at an SaO] of 82% (10 000 feet). The slope of the dose-response function was steeper for the low than for the high brightness condition. These results provide a threshold estimate of9750 feet for performance decrements due to hypoxia and point to the disruption of vision as a factor influencing this decrement.
A central feature of the impairment in performance produced by inert gas narcosis, which poses a threat to divers breathing compressed air, is a slowing of reaction time (RT). To investigate the locus of this slowing, the effects of 35% nitrous oxide on Crossman's confusion function were determined using line-length and weight discrimination tasks, with accuracy held constant. For both tasks narcosis slowed RT by increasing the intercept rather than the slope of Crossman's function. These results are interpreted in terms of additive factors method logic as being consistent with the predictions of the slowed processing model that has been proposed to account for the effects of narcosis on human performance.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.