The question of whether hiccups can be caught from another person is common, often fueled by the experience of seeing someone hiccup and feeling a sudden urge to do the same. This widespread idea suggests that these involuntary spasms are communicable. To understand this perception, we first examine the biological mechanism that causes a hiccup. This article will explore the physiology and clarify the difference between a true biological contagion and a behavioral suggestion.
The Science of Hiccups
A hiccup, medically termed singultus, is an involuntary, spasmodic contraction of the diaphragm muscle. This reflex action is governed by a complex neural pathway known as the hiccup reflex arc, involving several key nerves and brain structures. The afferent, or sensory, limb of this arc includes branches of the vagus and phrenic nerves, which transmit signals from the stomach, chest, and diaphragm up to the brainstem.
Once the central hiccup processing center in the brainstem receives this signal, it triggers the efferent, or motor, response. This motor signal travels back down the phrenic nerve to the diaphragm, causing it to contract suddenly and forcefully. Simultaneously, the vagus nerve causes the glottis—the space between the vocal cords—to snap shut about 35 milliseconds after the diaphragm’s contraction. The abrupt closure of the glottis against the rapidly inhaled air creates the characteristic “hic” sound.
Biological Contagion vs. Social Suggestion
Hiccups are not contagious in the biological sense, which requires the transmission of a pathogenic agent like a virus or bacterium. Singultus is a physical reflex arc triggered by internal stimuli, such as a swollen stomach, rapid eating, or nerve irritation. Since there is no infectious particle responsible for initiating the spasmodic diaphragm contraction, hiccups cannot be spread through the air or by contact.
However, the misconception of contagiousness often arises from the power of psychological suggestion and behavioral mimicry. When a person observes a noticeable, involuntary action, such as a yawn or a hiccup, it can sometimes trigger a similar response in the observer.
The human brain has neural systems, including the mirror neuron system, that are involved in observing and interpreting the actions of others. This system may contribute to a form of motor contagion where seeing an action makes performing it more likely, even if the action is involuntary. The mere expectation of hiccupping after witnessing it can itself become a psychological trigger, stimulating a response through the body’s mind-body connection. This observed social mimicry is what makes the experience feel like it has been “caught.”