Effects of negative ions on interpersonal attraction: evidence for intensification

In Study 1, female subjects received information suggesting either that a stranger (a female accomplice) shared their attitudes and evaluated them positively or that a stranger did not share their attitudes and evaluated them negatively. These procedures took place in the presence of a low (ambient) or high level of negative ions. On the basis of previous research, it was predicted that a high level of negative ions would intensify subjects' reactions to the stranger, thus enhancing their evaluations of her when she seemed to share their attitudes and to like them, but reducing these evaluations when she did not share their attitudes and disliked them. Results offered support for these predictions. In Study 2, female subjects performed two tasks (letter and digit copying) in the presence of a low or high concentration of negative ions. Their blood pressure and pulse were measured at several points during the experiment. Results indicated that on various trials both systolic and diastolic blood pressure were higher in the high-ions than in the low-ions condition. In addition, subjects reported higher levels of subjective arousal and made significantly more errors on the letter-copying task in the presence of a high concentration of negative ions. Together, the results of these studies were interpreted as offering support for the view that high concentrations of negative ions can increase both physiological and psychological (subjective) arousal.