The relationship between brainwave activity and IQ is complex. While some of the scientific literature mentions gamma brainwaves (40 – 99 Hz) as being associated with high IQ, certain scientific studies show no such correlation.

One study found that higher IQ individuals exhibited greater degrees of alpha brainwave (8 – 12 Hz) synchrony between the right and left hemispheres of the neocortex during eyes closed rest.

Other IQ-related studies involving brainwaves focus less on brainwave frequencies and instead find correlation between high IQ and how brainwaves manifest in different parts of the brain.

To make it even more complex, we now know that what is generally referenced as IQ represents only certain aspects of intelligence, such as spatial-temporal reasoning, logic, mathematics, pattern recognition, linguistics, cultural awareness, etc. As such, whatever the current brainwave studies tell us about intelligence is still very likely just a small slice of what the holistic gestalt of human intelligence really looks like.

Here we examine six scientific studies and what they tell us about the relationship between brainwave activity and intelligence:

Study #1: “Are Smarter Brains Faster? Heritability of Alpha Peak Frequency, IQ, and Their Interrelation,” conducted by D. Posthuma, M. C. Neale, D. I. Boomsma, and J. C. de Geus, and published in the scientific journal Behavior Genetics in 2001.

The authors of this study looked at the EEG recordings and IQ scores of 271 twin families (with a total of 688 participants) in order to see if there was a correlation between higher peak brain wave frequencies and higher intelligence scores. No correlation between faster brainwave frequencies and high IQ was found. However, this study alone is insufficient to conclude that there is no such correlation.

Study #2: “Increased IQ After Alpha Training,” conducted by James Hardt.

In a corporate training that was later published as a study, the staff of a company were given IQ tests immediately before receiving intensive alpha brainwave training using advanced neurofeedback equipment designed and developed by Dr. Hardt. The staff then underwent Dr. Hardt’s intensive training for one week. They were administered another IQ test four months after the training and were found to have increased their IQ by 11.7 points in a manner not accounted for by age or previous IQ. The trainees effectively increased their IQ scores simply by engaging in very intensive alpha brainwave training for the course of one week, with no apparent fading of the effect over time.

Study #3: “EEG and Intelligence: Relations between EEG coherence, EEG phase delay and power,” conducted by R. W. Thatcher, D. North and C. Biver, and published in the journal Clinical Neuropsychology in 2005.

This study examined synchrony between the peaks and troughs of brainwave patterns exhibited in human subjects sitting calmly with eyes closed. Higher IQ was found to be correlated with phase delay in the prefrontal cortex. The longer the phase delay between the prefrontal cortex and other areas of the brain, the higher was the IQ. This essentially means that the prefrontal cortex of highly intelligent people is so efficient and coherent in its functioning, that it energetically entrains other areas of the brain to synchronize with it, albeit with a bit of a lag in phase.

Study #4: “Brainwaves as markers of intelligence quotient and spiritual intelligence,” conducted by Sharma Priya and Singh Abha, and published in the International Journal of Indian Psychology in 2020.

Subjects in this study were assessed using EEG recordings and tests for IQ and spiritual intelligence. The authors concluded that alpha brainwaves (8 – 12 Hz), followed by theta waves (4 – 7 Hz), were the most reliable predictor of high IQ and spiritual intelligence.

Study #5: “Asymmetry pattern of resting EEG for different IQ levels,” conducted by A. H. Jahidin, et al, and published in the journal Procedia – Social and Behavioral Sciences in 2013.

This study examined 50 EEG samples, looking for asymmetry patterns of resting brainwaves for three different levels of intelligence, as indicated by the Raven Progressive Matrices. Smaller asymmetry scores between alpha and beta brainwave frequencies were exhibited by those with higher IQ scores, indicating a greater degree of coherence and synchrony in overall brainwave activity. This greater synchrony essentially manifests as a more balanced brainwave activity.

Study #6: “Intelligence Level Might Be Predicted By the Characteristics of EEG Signals at Specific Frequencies and Brain Regions,” conducted by Song Luo and associates, and published in the Journal of Mechanics in Medicine and Biology in 2021.

The total energy and distribution patterns of EEG signals from 43 students was examined in relation to IQ scores to see if the intensities of information flows could reveal a connection to higher intelligence. The results showed that higher IQ individuals required less mental resources for certain tasks than lower IQ individuals. This speaks again to the idea of increased synchrony, coherence and efficiency in higher IQ brains.

So, in terms of these studies and what they tell us about the relationship between brainwaves and intelligence, we can make the following five conclusions:

1. High IQ does not necessarily correlate with faster brainwave patterns such as gamma.
2. Intense alpha brainwave training can increase intelligence as measured by standard IQ tests, even when said training lasts only a week.
3. Increases in IQ resulting from such intensive alpha brainwave training appear to endure for at least several months after the initial training.
4. The appearance of alpha and theta brainwave frequencies while sitting calmly with eyes closed can predict higher scores in IQ and spiritual intelligence.
5. High IQ brains exhibit greater than normal brainwave synchrony, coherence and thus overall brain efficiency than lower IQ brains.

These five conclusions, however, are not necessarily set in stone. While they concur with the findings of these aforementioned six studies, we must not blindly assume that future studies will corroborate these findings. That said, based on previous neuroscientific research, it is likely that these five postulates have a good chance of standing the test of time.