Monroe Institute Research Files: Binaural Beats

slightly (mean 5 0.3, SE 5 0.2) when participants listened to the moment. The experimenter reviewed a summary of performance to theta/delta binaural beats during the vigilance task and dropped insure that instructions had been followed and reasonable levels of slightly (mean 5 20.4, SE 5 0.4) when they listened to beta success obtained. However, participants received only general binaural beats. positive feedback each day. Scores for vigor/activity did not contain a significant condition by period interaction, although there was a significant period effect RESULTS (F(1, 28) 5 25.02, p , 0.0001). Scores dropped from the begin- Vigilance Performance ning to the end of the task (mean 5 22.9). Task performance was scored as the number of correct target DISCUSSION detections (out of a possible 180 targets) and the number of false alarms (when a keypress response was made to a nontarget stim- The results of this study provide evidence that presentation of ulus). The number of hits and false alarms in the beta and theta/ simple binaural auditory beat stimuli during a 30-min vigilance delta binaural beat conditions were compared by paired t-test. task can affect both the task performance and the changes in mood Because we proposed a directional hypothesis, that beta frequency associated with the task. The observed effects were consistent with beats would improve performance compared to theta/delta fre- our predictions regarding differential effects on alertness and 252 LANE ET AL. mood. Binaural beats in the beta EEG frequency range were EEG spectral power in the beta or theta/delta bands. Such an associated with relative improvements in target detection and interpretation is consistent with earlier studies that suggest appar- reduction in the number of false alarms compared to binaural beats ent EEG changes in response to binaural beat stimulation (2), in the theta/delta EEG frequency range. Moreover, beta binaural although the evidence of such effects remains preliminary. The beats were associated with smaller increases in task-related con- present study lacked EEG measurements that could confirm this fusion and fatigue compared to theta/delta beats, and the two interpretation, but future studies can test this hypothesis directly. conditions had different effects on scores for depression/dejection. It is interesting to note that similar changes in performance of Scores on the confusion/bewilderment scale increased under a vigilance task were observed when normal volunteers were both conditions, but rose significantly more during theta/delta trained using biofeedback to increase or suppress EEG theta ac- frequency stimulation. This scale includes the items ‘‘confused,’’ tivity (1). Those trained experimental groups did differ both in ‘‘unable to concentrate,’’ ‘‘muddled,’’ ‘‘bewildered,’’ ‘‘efficient’’ theta activity and in vigilance performance during testing, and (scored in reverse). ‘‘forgetful,’’ and ‘‘uncertain about things.’’ It suppression of theta activity during the task was associated with appears to represent ‘‘a self-report of cognitive efficiency’’ (4). relatively better vigilance performance. Perhaps binaural-beat Changes observed in this study suggest that the theta/delta binaural stimulation provides an alternative means of suppressing theta beats produced a subjective impairment in the ability to think activity, or enhancing beta activity, to enhance performance. If so, clearly. Performance of the vigilance task also increased scores for it has the distinct advantage that it requires neither extensive fatigue/inertia in both conditions, but more so for the theta/delta training or intent to self-control EEG for its successful application. condition. This scale describes ‘‘a mood of weariness, inertia, and The observations in the present study have interesting implica- low energy level’’ (4) and includes ‘‘worn-out,’’ ‘‘listless,’’ ‘‘fa- tions. If binaural beat auditory stimulation can influence behavior tigued,’’ ‘‘exhausted,’’ ‘‘sluggish,’’ ‘‘weary,’’ and ‘‘bushed’’ as and mood, then such stimulation may have useful applications for its items. The depression/dejection scale represents depressed the self-control of arousal, attention, and performance. There may mood accompanied by a sense of inadequacy, and includes ‘‘un- be potential applications of these performance enhancing signals in happy,’’ ‘‘sorry,’’ ‘‘sad,’’ ‘‘miserable,’’ ‘‘hopeless,’’ ‘‘unwor- thy,’’ ‘‘discouraged,’’ ‘‘desperate,’’ and ‘‘worthless’’ among its situations that demand high levels of continuous sustained atten- items. Together these scales suggest that the negative changes in tion and performance, such as commercial highway driving or air mood produced by a monotonous task may have been partially traffic control. Performance enhancing stimulation may prove use- ameliorated by the presentation of beta-frequency binaural beats. ful in other occupational tasks as well. Conversely, binaural-beat These effects on behavior and mood were observed in the stimulation that decreases arousal may have applications in the absence of participant expectations, and experimental controls treatment of insomnia or stress. ruled out other ‘‘placebo’’ effects. Not only were participants The phenomenon of binaural auditory beat stimulation and its unaware of their treatment condition, they were unaware that psychophysiological consequences deserves further study. Addi- different binaural-beat treatments were being presented during the tional controlled studies will be required to determine what behav- three days of testing. Although experimenters knew the true nature ioral, affective, and cognitive effects different patterns of binaural of the study, they were careful to maintain the cover story through- beats might have and how any associated changes in physiology, out the study. Moreover, they were also blind to the order in which behavior, or subjective experience might be used. Little is known the experimental treatments were administered and thus could not about the mechanisms that may be involved in the transduction of systematically bias the results. simple auditory signals into changes in mood and performance We presume that the behavioral and mood effects were medi- demonstrated here. However, the results of this study demonstrate ated by changes in level of central nervous system arousal induced clearly that simple binaural-beat auditory stimulation can influence by binaural-beat stimulation. It is plausible that these signals psychomotor and affective processes, even when people are un- entrained corresponding EEG frequencies and increased relative aware that such signals are being presented. REFERENCES 1. Beatty, J.; Greenberg, A.; Deibler, W. P.; O’ Hanlon, J. F. Operant memory. 1994:http://www.MonroeInstitute.org/research/human- control of occipital theta rhythm affects performance in a radar moni- memory-kennerly.html toring task. Science 183:871– 873; 1974. 4. McNair, D. M.; Lorr, M.; Droppleman, L. F. EdITS manual for the 2. Foster, D. S., EEG and subjective correlates of alpha-frequency binau- profile of mood states. San Diego: EdITS;1992. ral-beat stimulation combined with alpha biofeedback. 1996:http://ww- 5. Monroe, R. A. Far journeys. New York: Doubleday;1985. w.MonroeInstitute.org/research/alpha-binaural-beat.html 6. Oster, G. Auditory beats in the brain. Sci. Am. 229:94 –102; 1973. 3. Kennerly, R. C., An empirical investigation into the effect of beta- 7. Russell, R., ed. Using the whole brain. Hampton Roads Publishing Co.: frequency binaural-beat audio signals on four measures of human Norfolk, VA; 1993.