How Hans Berger and EEG Revolutionized Psychological Science

This is the second of a two-part series on Hans Berger's discovery of EEG, and how it revolutionized psychological science. The first piece, on the historical context, can be found here.

When EEG entered the scientific toolkit, its impact was nothing less than revolutionary. For the first time, there was a direct window into the fully functioning brain. Instead of studying what happens when certain functions are disrupted, scientists could now investigate the functions themselves.

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Scientists quickly discovered that the brain produces broad patterns of activity, which correspond to a very general state of mind. These are called "waveforms." Berger himself ran experiments identifying alpha wave activity, neural oscillations in the frequency range of 8-12 Hz, that are apparent when one's eyes are closed or in a wakeful relaxation state. These are often called "Berger waves."

Later, neuroscientists would discover a whole host of waveform activity. This includes delta waves (4 Hz) associated with slow-wave sleep, Theta waves (4 Hz-7 Hz) associated with arousal, drowsiness, and in some cases, meditation, and Beta Waves (13 Hz-30 Hz) most present during simple motor behavior and analytical thinking, and more.

Berger's initial investigations paved the way for a broad understanding of brain pattern activity that still serves as the foundation for modern neuroscience.

From EEG to ERPs

Of course, EEG is not without its drawbacks. Given that it's a direct measure from the brain's surface, EEG is limited in that it can only reliably measure activity from the outer few millimeters of the brain, known as the cortex. It can't examine activity in the brain much deeper than that.

It's also not an ideal technology to study where exactly something happens along the cortex. You can see whether this occurs on the left or right side of the brain and in which general part of what lobe, but you can't get much more specific than that. We're talking inches, not millimeters.

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But what EEG loses in spatial resolution, it makes up for in its temporal resolution. That is, it's not great at finding where something happens in the brain, but it's superb at identifying when things happen—down to the millisecond. For this reason, EEG responses can be timed to specific events in a methodology called event-related potentials (ERPs).

ERPs tell us about the brain's reaction to something very specific. For example, one common use is for measuring the responses to individual words, by measuring a pattern of brain activity known as the n400 response. The n400 is often associated with psychological surprise. But more accurately, its function is tied to semantic retrieval: the easier it is to retrieve a word's meaning, the lower the n400 response is. Conversely, the harder it is for the brain to recover the word's meaning, the stronger the n400 response.

So when you have a sentence like, "I went to the store to buy some ___________," the n400 response to the word "groceries" here will be much lower than the n400 response to "gorilla." Since you're not likely to expect the latter, it's much more difficult to retrieve it, given the preceding sentence.

Given this exceptional timing (which far exceeds that of other modern techniques such as fMRI), EEG is a powerful tool for studying language. And when it comes to examining quick processing in the cortex, it remains unrivaled.

Final Thoughts on Hans Berger

Since Berger's day, EEG technology has vastly improved, and analyzing its data has become much more sophisticated. But the basic technology—measuring brain activity from the scalp with electrodes—remains hugely influential. It was a revolutionary instrument for its time and remains a powerful tool for studying the neuroscience of human nature. It's an especially crucial tool for studying consumer psychology, and lightweight mobile versions are also heavily used in phygital marketing.

Source: DeepMind via UnSplash

While he employed an empirical methodology to probe his area of inquiry, his ultimate motivation was pure, inexplicable emotion. His central research question—the origins of telepathy—was rife with assumptions that went utterly unquestioned. He was trying to uncover the scientific basis of something that doesn't exist.

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Before his life-changing brush with telepathy, Hans Berger fancied himself an astronomer. We'll never know what contributions he may have made to that field, and they have been noteworthy. But as it turned out, he became a neuroscientist enamored with psychic forces.

In all its irrational glory, this obsession ultimately drove a scientific breakthrough. And in doing so, changed psychology forever.

This piece also appears on the human nature blog "NeuroScience Of"