entrainment

Entrained systems are those whose rhythms become synchronized through interaction or a common external influence. Entrainment results in a shared frequency and a stable phase relationship, even when the individual components have different natural frequencies.

Entrainment occurs in many contexts through direct coupling between oscillators or through a shared environment. When oscillators influence one another, they can settle into frequency-locked or phase-locked states. In fluid dynamics, entrainment describes the pulling along of surrounding fluid or particles by a moving body or by turbulent flow. In chronobiology, circadian entrainment occurs when internal biological clocks align with environmental cues such as the light-dark cycle, temperature, or feeding schedules.

In neuroscience and psychology, neural or sensory entrainment happens when brain circuits or perceptual systems synchronize to rhythmic stimuli, such as music or speech. This synchronization can enhance perception, attention, and motor coordination, and is studied across cognitive neuroscience, psychology, and related fields.

Entrainment has practical implications in engineering, medicine, and daily life. It underpins synchronization in electrical grids and communication systems, and it informs therapeutic approaches that use rhythmic stimulation. It is also observed in nature, for example in the synchronized flashing of fireflies or in coordinated group movements among animals. Entrainment is typically robust under appropriate conditions but can be sensitive to noise, variability in intrinsic frequencies, or changes in the environment that disrupt coupling.