Effects of negative ions on cognitive performance.

Abstract

Male and female subjects (undergraduate students) participated in two studies designed to investigate the impact of negative air ions on cognitive performance. In the first experiment, they worked on three different tasks (proofreading, memory span, word finding) in the presence of low, moderate, or high concentrations of such ions. Results indicated that among men, performance on two of these tasks (proofreading and memory span) was enhanced by moderate but not by high concentrations of ions. In the second experiment, undertaken to extend the generality of these initial results, male and female subjects performed two additional tasks (letter copying, decision making) in the presence of low, moderate, or high concentrations of ions. Output on the letter copying task increased significantly as ion level rose among both sexes. With respect to decision making, the tendency of male (but not female) participants to select initially preferred alternatives was significantly enhanced by moderate concentrations of negative ions. Together, the findings of these studies suggest that negative air ions can indeed exert appreciable effects on cognitive performance. However, contrary to claims often associated with advertising for commercially produced ion generators, these effects are neither simple nor uniformly beneficial in nature.