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Table 1 Introduction to brain wave

From: Emotion classification based on brain wave: a survey

WaveState of consciousnessFrequency (Hz)Psychological state
\(\delta\)Unconscious level1–3\(\delta\) usually appear in the deep sleep state of adults and are also the most important brain waves in infants
\(\delta\) are often used as a basis for sleep therapy, such as [12, 13], which detects the amount of energy released by the patient’s Delta wave and determines whether it has entered a deep sleep state
\(\delta\) are needed to regain physical sleep
\(\theta\)Subconscious level4–7\(\theta\) usually appear in a shallow sleep state, also as a meditative state, referring to the brain waves that manifest when they first fall asleep
When we perform memory, perceptual, and emotional-related behaviors, \(\theta\) are higher because the brain acts as a memory, and behavior is trained as an unconscious action
\(\alpha\)
 Low \(\alpha\)Consciousness and subconscious level8–9It is the main brain wave of normal relaxed adults
Consciousness gradually moves towards ambiguity
It’s also about relaxation and freedom
The \(\upalpha\) is related to the active activity of the brain [14], and when the energy released by the Alpha Wave is strong, it represents the brain wave in the best state of learning and thinking
 High \(\alpha\)10–12
\(\beta\)
 Low \(\beta\)Level of consciousness13–17\(\beta\) are associated with concentration, and when beta waves emit higher energy, they represent a positive increase in attention
 High \(\beta\)18–30
\(\gamma\)
 Low \(\gamma\)Level of consciousness31–40\(\upgamma\) are associated with happiness
When the energy released by the Gamma Wave is higher, it represents a higher sense of happiness. \(\upgamma\) are associated with reducing stress
When the energy released by the \(\upgamma\) is higher, the more pressure is released
 High \(\gamma\)41–50