Laughter is an audible expression, or appearance of merriment or happiness, or an inward feeling of joy and pleasure (laughing on the inside). It may ensue (as a physiological reaction) from jokes, tickling, and other stimuli. Inhaling nitrous oxide can also induce laughter; other drugs, such as cannabis, can also induce episodes of strong laughter. Strong laughter can sometimes bring an onset of tears or even moderate muscular pain.
Laughter is a part of human behaviour regulated by the brain. It helps humans clarify their intentions in social interaction and provides an emotional context to conversations. Laughter is used as a signal for being part of a group — it signals acceptance and positive interactions with others. Laughter is sometimes seemingly contagious, and the laughter of one person can itself provoke laughter from others as a positive feedback. This may account in part for the popularity of laugh tracks in situation comedy television shows.
The study of humor and laughter, and its psychological and physiological effects on the human body is called gelotology.
Laughter in animals
Laughter is not confined or unique to humans, despite Aristotle's observation that "only the human animal laughs". The differences between the laughter of chimpanzees and humans may be the result of adaptations that evolved to enable human speech. However, some behavioral psychologists argue that self-awareness of one's situation, or the ability to identify with another's predicament are prerequisites for laughter, and thus certain animals are not laughing in the "human manner".
Laughter is a rich experience and expression in human beings. Thus there are several shades of smiling and laughing expressions. They involve elaborate neurophysiological and physiological processes. Such laughter is not often seen in animals. Nevertheless, one can not deny occurrences of primitive laughter in terms of experience and expression in animals. Owners of pets can vouch on this point, if they understand when their pet is happy and how it expresses the same.
According to Dr. Shriniwas Kashalikar, self awareness is conscious concommitant of the physiological processes involving laughter or smiling reflex [response] and its grades, degrees or spectrum varies according to phylogenetic development, with no clear cut demarcation. The emotional ingredients [such as contempt, hatred, ridicule, sarcasm, love, amusement etc] are variable and involve different neurophysiological and physiological processes.
Self awareness and ability to identify with another's predicament may be prerequisite to intellectual jokes with specific references and contexts, but not for laughing behavior as such.
Research of laughter in animals may identify new molecules to alleviate depression, disorders of excessive exuberance such as mania and ADHD, or addictive urges and mood imbalances.
show laughter-like vocalizations in response to physical contact, such as wrestling, play chasing, or tickling. This is documented in wild and captive chimpanzees. Chimpanzee laughter is not readily recognizable to humans as such, because it is generated by alternating inhalations and exhalations that sound more like breathing and panting. The differences between chimpanzee and human laughter may be the result of adaptations that have evolved to enable human speech. There are instances in which non-human primates have been reported to have expressed joy. One study analyzed and recorded sounds made by human babies and bonobos (also known as pygmy chimpanzees) when tickled. It found that although the bonobo’s laugh was a higher frequency, the laugh followed the same spectrographic pattern of human babies to include as similar facial expressions. Humans and chimpanzees share similar ticklish areas of the body such as the armpits and belly. The enjoyment of tickling in chimpanzees does not diminish with age. Discovery 2003A
chimpanzee laughter sample. Goodall 1968 & Parr 2005
It has been discovered that rats
emit short, high frequency, ultrasonic, socially induced vocalization during rough and tumble play and when tickled. The vocalization is described a distinct “chirping”. Humans cannot hear the "chirping" without special equipment. It was also discovered that like humans, rats have "tickle skin". These are certain areas of the body that generate more laughter response than others. The laughter is associated with positive emotional feelings and social bonding occurs with the human tickler, resulting in the rats becoming conditioned to seek the tickling. Additional responses to the tickling were those that laughed the most also played the most, and those that laughed the most preferred to spend more time with other laughing rats. This suggests a social preference to other rats exhibiting similar responses. However, as the rats age, there does appear to be a decline in the tendency to laugh and respond to tickle skin. The initial goal of Jaak Panksepp
and Jeff Burgdorf’s research was to track the biological origins of joyful and social processes of the brain by comparing rats and their relationship to the joy and laughter commonly experienced by children in social play. Although, the research was unable to prove rats have a sense of humour, it did indicate that they can laugh and express joy. Panksepp & Burgdorf 2003
Chirping by rats is also reported in additional studies by Brain Knutson of the National Institutes of Health. Rats chirp when wrestling one another, before receiving morphine, or when mating. The sound has been interpreted as an expectation of something rewarding. Science News 2001
laugh sounds similar to a normal pant. But by analyzing the pant using a sonograph
, this pant varies with bursts of frequencies, resulting in a laugh. When this recorded dog-laugh vocalization is played to dogs in a shelter setting, it can initiate play, promote pro-social behavior, and decrease stress levels. In a study by Simonet, Versteeg, and Storie, 120 subject dogs in a mid-size county animal shelter were observed. Dogs ranging from 4 months to 10 years of age were compared with and without exposure to a dog-laugh recording. The stress behaviors measured included panting, growling, salivating, pacing, barking, cowering, lunging, play-bows, sitting, orienting and lying down. The study resulted in positive findings when exposed to the dog laughing: significantly reduced stress behaviors, increased tail wagging and the display of a play-face when playing was initiated, and the increase of pro-social behavior such as approaching and lip licking were more frequent. This research suggests exposure to dog-laugh vocalizations can calm the dogs and possibly increase shelter adoptions. Simonet, Versteeg, & Storie 2005
A dog laughter sample. Simonet 2005
Recently researchers have shown infants as early as 17 days old have vocal laughing sounds or spontaneous laughter. Early Human Development 2006This conflicts with earlier studies indicating that babies usually start to laugh at about four months of age; J.Y.T. Greig writes, quoting ancient authors, that laughter is not believed to begin in a child until the child is forty days old. "Laughter is Genetic" Robert R. Provine, Ph.D. has spent decades studying laughter. In his interview for WebMD, he indicated "Laughter is a mechanism everyone has; laughter is part of universal human vocabulary. There are thousands of languages, hundreds of thousands of dialects, but everyone speaks laughter in pretty much the same way.” Everyone can laugh. Babies have the ability to laugh before they ever speak. Children who are born blind and deaf still retain the ability to laugh. “Even apes have a form of ‘pant-pant-pant’ laughter.”
Provine argues that “Laughter is primitive, an unconscious vocalization.” And if it seems you laugh more than others, Provine argues that it probably is genetic. In a study of the “Giggle Twins,” two exceptionally happy twins were separated at birth and not reunited until 43 years later. Provine reports that “until they met each other, neither of these exceptionally happy ladies had known anyone who laughed as much as she did.” They reported this even though they both had been brought together by their adoptive parents they indicated were “undemonstrative and dour.” Provine indicates that the twins “inherited some aspects of their laugh sound and pattern, readiness to laugh, and perhaps even taste in humor.” WebMD 2002
Raju Mandhyan states "The physical and psychological benefits of laughter come second only to the physical and psychological benefits of sex."
Men and women take jokes differently. A study that appeared in Proceedings of the National Academy of Sciences
found in a study, 10 men and 10 women all watched 10 cartoons
, rating them funny or not funny and if funny, how funny on a scale of 1–10. While doing this, their brains were scanned by functional magnetic resonance imaging
(fMRI). Men and women for the most part agreed which cartoons were funny. However, their brains handled humor differently. Women’s brains showed more activity in certain areas, including the nucleus accumbens
. When women viewed cartoons they did not find humorous, their nucleus accumbens had a “ho-hum response.” A man's nucleus accumbens did not react to funny cartoons, and its natural activity level dropped during unfunny cartoons.
Researchers suspect the element of surprise may be at the heart of the study. They suggested that maybe women did not expect the cartoons to be funny, while men did the opposite. When the men in the study “got what they expected, their nucleus accumbens were calm.” However, the women’s brains could have had increased activity when they were “pleasantly surprised” by the cartoons’ humour. Researchers also suspect that men might have been “let down by unfunny cartoons, causing a dip in that brain area’s activity.”
It was indicated that this study might be a clue about the different emotional responses between men and women and could help with depression research. The research suggests men and women “differ in how humour is used and appreciated,” says Allan Reiss, M.D. WebMD 2005
Laughter and the brain
Modern neurophysiology states that laughter is linked with the activation of the ventromedial prefrontal cortex, which produces endorphins after a rewarding activity.
Research has shown that parts of the limbic system are involved in laughter. The limbic system is a primitive part of the brain that is involved in emotions and helps us with basic functions necessary for survival. Two structures in the limbic system are involved in producing laughter: the amygdala and the hippocampus.
The December 7, 1984 Journal of the American Medical Association describes the neurological causes of laughter as follows:
- "Although there is no known 'laugh center' in the brain, its neural mechanism has been the subject of much, albeit inconclusive, speculation. It is evident that its expression depends on neural paths arising in close association with the telencephalic and diencephalic centers concerned with respiration. Wilson considered the mechanism to be in the region of the mesial thalamus, hypothalamus, and subthalamus. Kelly and co-workers, in turn, postulated that the tegmentum near the periaqueductal grey contains the integrating mechanism for emotional expression. Thus, supranuclear pathways, including those from the limbic system that Papez hypothesised to mediate emotional expressions such as laughter, probably come into synaptic relation in the reticular core of the brain stem. So while purely emotional responses such as laughter are mediated by subcortical structures, especially the hypothalamus, and are stereotyped, the cerebral cortex can modulate or suppress them."
Laughter and the body
Gelotology is the study of physiological effects of humor and laughter.
Therapeutic effects of laughter
While it is normally only considered cliché that "laughter is the best medicine," specific medical theories attribute improved health, increased life expectancy, and overall improved well-being, to laughter.
A study demonstrated neuroendocrine and stress-related hormones decreased during episodes of laughter, which provides support for the claim that humour can relieve stress. Presenting their findings at the 121st Annual Meeting of the American Physiological Society, researchers have also found that the anticipation of a positive humorous laughter experience reduces potentially detrimental stress hormones, cortisol, epinephrine and dopac. The stress hormones were reduced 39, 70 and 38 percent, respectively
Writer Norman Cousins wrote about his experience with laughter in helping him recover from a serious illness in 1979's Anatomy of an Illness As Perceived by the Patient. In 1989, the Journal of the American Medical Association published an article, wherein the author wrote that "a humor therapy program can increase the quality of life for patients with chronic problems and that laughter has an immediate symptom-relieving effect for these patients, an effect that is potentiated when laughter is induced regularly over a period".
Some therapy movements like Re-evaluation Counseling believe that laughter is a type of "bodily discharge", along with crying, yawning and others, which requires encouragement and support as a means of healing.
Researchers frequently learn how the brain functions by studying what happens when something goes wrong. People with certain types of brain damage produce abnormal laughter. This is found most often in people with pseudobulbar palsy, gelastic epilepsy and, to a lesser degree, with multiple sclerosis, amyotrophic lateral sclerosis (ALS) , and some brain tumors. Inappropriate laughter is considered symptomatic of psychological disorders including dementia and hysteria, but can also be the result of cerebellar lesions or cerebral pathologies causing Pathological Laughter, curable by antidepressants, such as SSRIs or tricyclic antidepressants. The aforementioned cerebral damage-induced laughter includes corticospinal damage, which is known to sometimes induce laughter caused by abnormal sensory feedback due to perioral muscle tone fluctuations. Some negative medical effects of laughter have been reported as well, including laughter syncope, where laughter causes a person to lose consciousness.
Common causes for laughter are sensations of joy and humor, however other situations may cause laughter as well.
A general theory that explains laughter is called the relief theory. Sigmund Freud summarized it in his theory that laughter releases tension and "psychic energy". This theory is one of the justifications of the beliefs that laughter is beneficial for one's health. This theory explains why laughter can be as a coping mechanism for when one is upset, angry or sad.
Philosopher John Morreall theorizes that human laughter may have its biological origins as a kind of shared expression of relief at the passing of danger.
For example, this is how this theory works in the case of humour: a joke creates an inconsistency, the sentence appears to be not relevant, and we automatically try to understand what the sentence says, supposes, doesn't say, and implies; if we are successful in solving this 'cognitive riddle', and we find out what is hidden within the sentence, and what is the underlying thought, and we bring foreground what was in the background, and we realize that the surprise wasn't dangerous, we eventually laugh with relief. Otherwise, if the inconsistency is not resolved, there is no laugh, as Mack Sennett pointed out: "when the audience is confused, it doesn't laugh" (this is the one of the basic laws of a comedian, called "exactness"). It is important to note that the inconsistency may be resolved, and there may still be no laugh. Due to the fact that laughter is a social mechanism, we may not feel like we are in danger, however, the physical act of laughing may not take place. In addition, the extent of the inconsistency (timing, rhythm, etc) has to do with the amount of danger we feel, and thus how intense or long we laugh. This explanation is also confirmed by modern neurophysiology (see section Laughter and the Brain)
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