Effects of State‐Trait Anxiety on the Ability to Enhance and Suppress EEG Alpha

The purpose of this study was to explore the relationship between self‐reported state and trait anxiety and the ability to enhance or suppress (i.e., control) alpha density in a biofeedback situation. Forty subjects were randomly divided into alpha enhancement and alpha suppression conditions and then underwent four 40‐min eyes‐closed biofeedback sessions. Immediately before and after each session, each subject completed the A‐State scale of the State‐Trait Anxiety Inventory (STAI). Prior to the first session and again at the end of the final session, the A‐Trait scale of the STAI was also completed. The results indicated that: a) subjects with low initial trait and state anxiety were significantly better than high anxiety subjects at suppressing but not enhancing alpha, b) final state anxiety scores were unrelated to alpha control, and c) significant pre‐ to post‐session declines in state anxiety across all subjects were unrelated to both the direction and success of alpha control. It was concluded that anxiety may be related to the ability to increase cortical arousal level (i.e., to reduce alpha) in a biofeedback situation rather than being a direct correlate of alpha level per se. However, since the biofeedback procedure did not result in significant alpha enhancement, the relationship between anxiety and the ability to reduce cortical arousal remains unclear.