Autistic adults perceive and experience laughter differently to non-autistic adults.

Human interaction is immersed in laughter; though genuine and posed laughter are acoustically distinct, they are both crucial socio-emotional signals. In this novel study, autistic and non-autistic adults explicitly rated the affective properties of genuine and posed laughter. Additionally, we explored whether their self-reported everyday experiences with laughter differ. Both groups could differentiate between these two types of laughter. However, autistic adults rated posed laughter as more authentic and emotionally arousing than non-autistic adults, perceiving it to be similar to genuine laughter. Autistic adults reported laughing less, deriving less enjoyment from laughter, and experiencing difficulty in understanding the social meaning of other people's laughter compared to non-autistic people. Despite these differences, autistic adults reported using laughter socially as often as non-autistic adults, leveraging it to mediate social contexts. Our findings suggest that autistic adults show subtle differences in their perception of laughter, which may be associated with their struggles in comprehending the social meaning of laughter, as well as their diminished frequency and enjoyment of laughter in everyday scenarios. By combining experimental evidence with first-person experiences, this study suggests that autistic adults likely employ different strategies to understand laughter in everyday contexts, potentially leaving them socially vulnerable in communication.

Mapping the differential impact of spontaneous and conversational laughter on brain and mind: an fMRI study in autism.

Spontaneous and conversational laughter are important socio-emotional communicative signals. Neuroimaging findings suggest that non-autistic people engage in mentalizing to understand the meaning behind conversational laughter. Autistic people may thus face specific challenges in processing conversational laughter, due to their mentalizing difficulties. Using fMRI, we explored neural differences during implicit processing of these two types of laughter. Autistic and non-autistic adults passively listened to funny words, followed by spontaneous laughter, conversational laughter, or noise-vocoded vocalizations. Behaviourally, words plus spontaneous laughter were rated as funnier than words plus conversational laughter, and the groups did not differ. However, neuroimaging results showed that non-autistic adults exhibited greater medial prefrontal cortex activation while listening to words plus conversational laughter, than words plus genuine laughter, while autistic adults showed no difference in medial prefrontal cortex activity between these two laughter types. Our findings suggest a crucial role for the medial prefrontal cortex in understanding socio-emotionally ambiguous laughter via mentalizing. Our study also highlights the possibility that autistic people may face challenges in understanding the essence of the laughter we frequently encounter in everyday life, especially in processing conversational laughter that carries complex meaning and social ambiguity, potentially leading to social vulnerability. Therefore, we advocate for clearer communication with autistic people.

Recognition of emotions in German laughter across cultures.

Laughter conveys a wide range of information relevant for social interaction. In previous research we have shown that laughter can convey information about the sender's emotional state, however other research did not find such an effect. This paper aims to replicate our previous study using participant samples of diverse cultural backgrounds. 161 participants from Poland, the UK, India, Hong Kong, and other countries classified 121 spontaneously emitted German laughter sounds according to the laughter type, i.e., joyful, schadenfreude, and tickling laughter. Results showed that all participant groups classified the laughter sounds above chance level, and that there is a slight ingroup advantage for Western listeners. This suggests that classification of laughter according to the sender's emotional state is possible across different cultures, and that there might be a small advantage for classifying laughter of close cultural proximity.

Mini-review: Wild laughs: Ontogenesis and phylogenesis of humour.

This mini-review discusses the existing evidence on various forms of humour and humour-like behaviour in non-human animals, combining ontogenetic and phylogenetic perspectives. The first section describes humour-like behaviours, from the simplest to the most complex form (from laughing, tickling, joking, and chasing to ToM humour). In the second section, we propose the SPeCies (Social, Physiological, and Cognitive) Perspective, which frames the various types of humour based on Social motivation, Physiological state, and Cognitive skills. Finally, in the third section, we discuss future directions for further development.

'Should we laugh?' Acoustic features of (in)voluntary laughters in spontaneous conversations.

Laughter is one of the most common non-verbal features; however, contrary to the previous assumptions, it may also act as signals of bonding, affection, emotional regulation agreement or empathy (Scott et al. Trends Cogn Sci 18:618-620, 2014). Although previous research agrees that laughter does not form a uniform group in many respects, different types of laughter have been defined differently by individual research. Due to the various definitions of laughter, as well as their different methodologies, the results of the previous examinations were often contradictory. The analysed laughs were often recorded in controlled, artificial situations; however, less is known about laughs from social conversations. Thus, the aim of the present study is to examine the acoustic realisation, as well as the automatic classification of laughter that appear in human interactions according to whether listeners consider them to be voluntary or involuntary. The study consists of three parts using a multi-method approach. Firstly, in the perception task, participants had to decide whether the given laughter seemed to be rather involuntary or voluntary. In the second part of the experiment, those sound samples of laughter were analysed that were considered to be voluntary or involuntary by at least 66.6% of listeners. In the third part, all the sound samples were grouped into the two categories by an automatic classifier. The results showed that listeners were able to distinguish laughter extracted from spontaneous conversation into two different types, as well as the distinction was possible on the basis of the automatic classification. In addition, there were significant differences in acoustic parameters between the two groups of laughter. The results of the research showed that, although the distinction between voluntary and involuntary laughter categories appears based on the analysis of everyday, spontaneous conversations in terms of the perception and acoustic features, there is often an overlap in the acoustic features of voluntary and involuntary laughter. The results will enrich our previous knowledge of laughter and help to describe and explore the diversity of non-verbal vocalisations.

"Not in the mood": The fear of being laughed at is better predicted by humor temperament traits than diagnosis in neurodevelopmental conditions.

BACKGROUND: Research has shown that autistic individuals seem to be more prone to develop gelotophobia (i.e., the fear of being laughed at) than typically developing individuals. The goals of the present study were to discover whether the high levels of gelotophobia found in autism in previous studies were replicated here, to expand the research to Down syndrome (DS) and Williams syndrome (WS), and to assess the relation between individual differences and social impairments, affective predispositions, and humor temperament. METHODS: Questionnaires were distributed to parents of autistic individuals (N = 48), individuals with DS (N = 139), and individuals with WS (N = 43) aged between 5 and 25 years old. RESULTS: Autistic individuals were shown to frequently experience at least a slight level of gelotophobia (45%), compared to only 6% of individuals with DS and 7% of individuals with WS. Interestingly, humorless temperament traits (i.e., seriousness and bad mood) manifested as the strongest predictors of gelotophobia. This relation even transcended group differences. CONCLUSION: The results confirm that gelotophobia seems to be particularly concerning for autistic individuals, whereas individuals with DS and WS seem to be more protected from developing such a fear. Moreover, it appears that gelotophobia seems to be more linked to high seriousness and irritability than diagnosis.

Real-time magnetic resonance imaging reveals distinct vocal tract configurations during spontaneous and volitional laughter.

A substantial body of acoustic and behavioural evidence points to the existence of two broad categories of laughter in humans: spontaneous laughter that is emotionally genuine and somewhat involuntary, and volitional laughter that is produced on demand. In this study, we tested the hypothesis that these are also physiologically distinct vocalizations, by measuring and comparing them using real-time magnetic resonance imaging (rtMRI) of the vocal tract. Following Ruch and Ekman (Ruch and Ekman 2001 In Emotions, qualia, and consciousness (ed. A Kaszniak), pp. 426-443), we further predicted that spontaneous laughter should be relatively less speech-like (i.e. less articulate) than volitional laughter. We collected rtMRI data from five adult human participants during spontaneous laughter, volitional laughter and spoken vowels. We report distinguishable vocal tract shapes during the vocalic portions of these three vocalization types, where volitional laughs were intermediate between spontaneous laughs and vowels. Inspection of local features within the vocal tract across the different vocalization types offers some additional support for Ruch and Ekman's predictions. We discuss our findings in light of a dual pathway hypothesis for the neural control of human volitional and spontaneous vocal behaviours, identifying tongue shape and velum lowering as potential biomarkers of spontaneous laughter to be investigated in future research. This article is part of the theme issue 'Cracking the laugh code: laughter through the lens of biology, psychology and neuroscience'.

The different shades of laughter: when do we laugh and when do we mimic other's laughter?

Laughter is an ambiguous phenomenon in response to both positive and negative events and a social signal that coordinates social interactions. We assessed (i) who laughs and why, and (ii) if the type of laughter and whether the observer approves of it impact on facial mimicry as a proxy for shared laughter. For this, 329 participants watched funny, schadenfreude and disgusting scenes and then saw individuals who purportedly reacted to each scene while participants' facial expressions were recorded and analysed. Participants laughed more in response to funny than in response to schadenfreude scenes and least in response to disgust scenes, and laughter within each scene could be explained both by situational perceptions of the scenes as well as by individual differences. Furthermore, others' laughter in response to funny scenes was perceived as more appropriate, elicited more closeness and more laughter mimicry than others' laughter in response to schadenfreude and especially in response to disgust scenes. Appropriateness and closeness as well as individual differences could explain laughter mimicry within each scene. This is in line with the notion that laughter is not per se an affiliative signal and that different types of laughter have distinct social implications. This article is part of the theme issue 'Cracking the laugh code: laughter through the lens of biology, psychology and neuroscience'.

Tendency to laugh is a stable trait: findings from a round-robin conversation study.

People often laugh during conversation. Who is more responsible for the laughter, the person laughing or their partner for eliciting it? We used a round-robin design where participants (N = 66) engaged in 10 different conversations with 10 same-gender strangers and counted the instances of laughter for each person in each conversation. After each conversation, participants rated their perceived similarity with their partner and how much they enjoyed the conversation. More than half the variability in the amount a person laughed was attributable to the person laughing-some people tend to laugh more than others. By contrast, less than 5% of the variability was attributable to the laugher's partner. We also found that the more a person laughed, the more their partners felt similar to them. Counterintuitively, laughter negatively predicted conversation enjoyment. These findings suggest that, in conversations between strangers, laughter may not be a straightforward signal of amusement, but rather a social tool. We did not find any personality predictors of how much a person laughs or elicits laughter. In summary, how much a person laughs in conversation appears to be a stable trait associated with being relatable, and is not necessarily reflective of enjoyment. This article is part of the theme issue 'Cracking the laugh code: laughter through the lens of biology, psychology and neuroscience'.

Laughter and culture.

Like most human non-verbal vocalizations, laughter is produced by speakers of all languages, across all known societies. But despite this obvious fact (or perhaps because of it), there is little comparative research examining the structural and functional similarity of laughter across speakers from different cultures. Here, we describe existing research examining (i) the perception of laughter across disparate cultures, (ii) conversation analysis examining how laughter manifests itself during discourse across different languages, and (iii) computational methods developed for automatically detecting laughter in spoken language databases. Together, these three areas of investigation provide clues regarding universals and cultural variations in laughter production and perception, and offer methodological tools that can be useful for future large-scale cross-cultural studies. We conclude by providing suggestions for areas of research and predictions of what we should expect to discover. Overall, we highlight how important questions regarding human vocal communication across cultures can be addressed through the examination of spontaneous and volitional laughter. This article is part of the theme issue 'Cracking the laugh code: laughter through the lens of biology, psychology and neuroscience'.

Robert Provine: the critical human importance of laughter, connections and contagion.

Robert Provine made several critically important contributions to science, and in this paper, we will elaborate some of his research into laughter and behavioural contagion. To do this, we will employ Provine's observational methods and use a recorded example of naturalistic laughter to frame our discussion of Provine's work. The laughter is from a cricket commentary broadcast by the British Broadcasting Corporation in 1991, in which Jonathan Agnew and Brian Johnston attempted to summarize that day's play, at one point becoming overwhelmed by laughter. We will use this laughter to demonstrate some of Provine's key points about laughter and contagious behaviour, and we will finish with some observations about the importance and implications of the differences between humans and other mammals in their use of contagious laughter. This article is part of the theme issue 'Cracking the laugh code: laughter through the lens of biology, psychology and neuroscience'.

The naturalistic approach to laughter in humans and other animals: towards a unified theory.

This opinion piece aims to tackle the biological, psychological, neural and cultural underpinnings of laughter from a naturalistic and evolutionary perspective. A naturalistic account of laughter requires the revaluation of two dogmas of a longstanding philosophical tradition, that is, the quintessential link between laughter and humour, and the uniquely human nature of this behaviour. In the spirit of Provine's and Panksepp's seminal studies, who firstly argued against the anti-naturalistic dogmas, here we review compelling evidence that (i) laughter is first and foremost a social behaviour aimed at regulating social relationships, easing social tensions and establishing social bonds, and that (ii) homologue and homoplasic behaviours of laughter exist in primates and rodents, who also share with humans the same underpinning neural circuitry. We make a case for the hypothesis that the contagiousness of laughter and its pervasive social infectiousness in everyday social interactions is mediated by a specific mirror mechanism. Finally, we argue that a naturalistic account of laughter should not be intended as an outright rejection of classic theories; rather, in the last part of the piece we argue that our perspective is potentially able to integrate previous viewpoints-including classic philosophical theories-ultimately providing a unified evolutionary explanation of laughter. This article is part of the theme issue 'Cracking the laugh code: laughter through the lens of biology, psychology and neuroscience'.

The web of laughter: frontal and limbic projections of the anterior cingulate cortex revealed by cortico-cortical evoked potential from sites eliciting laughter.

According to an evolutionist approach, laughter is a multifaceted behaviour affecting social, emotional, motor and speech functions. Albeit previous studies have suggested that high-frequency electrical stimulation (HF-ES) of the pregenual anterior cingulate cortex (pACC) may induce bursts of laughter-suggesting a crucial contribution of this region to the cortical control of this behaviour-the complex nature of laughter implies that outward connections from the pACC may reach and affect a complex network of frontal and limbic regions. Here, we studied the effective connectivity of the pACC by analysing the cortico-cortical evoked potentials elicited by single-pulse electrical stimulation of pACC sites whose HF-ES elicited laughter in 12 patients. Once these regions were identified, we studied their clinical response to HF-ES, to reveal the specific functional target of pACC representation of laughter. Results reveal that the neural representation of laughter in the pACC interacts with several frontal and limbic regions, including cingulate, orbitofrontal, medial prefrontal and anterior insular regions-involved in interoception, emotion, social reward and motor behaviour. These results offer neuroscientific support to the evolutionist approach to laughter, providing a possible mechanistic explanation of the interplay between this behaviour and emotion regulation, speech production and social interactions. This article is part of the theme issue 'Cracking the laugh code: laughter through the lens of biology, psychology and neuroscience'.

Pathological laughter and crying in neurological disorders: recognition and treatment.

Pathological laughter and crying is a disabling symptom complex associated with damage to various central nervous system pathways that control the reflex motor component of emotional expression. Many underlying conditions-including neurodegenerative diseases, CNS inflammation, vascular lesions and traumatic brain injury-can be associated with disinhibition of emotional reflex control. This suggests a disruption of anatomical and functional networks, rather than any specific unifying pathological process. There is a wide differential diagnosis, including depression, dementia and other forms of behavioural disturbance. Diagnostic criteria and rating scales can help with clinical assessments and facilitate clinical trials. There is now good-quality evidence for a combination of dextromethorphan and quinidine, with weaker evidence for tricyclic and selective serotonin reuptake inhibitor antidepressants. Pathological laughter and crying is disabling and underdiagnosed but potentially treatable, and its wider recognition is important.

Involuntary Emotional Expression Disorder in a Patient With Toluene Leukoencephalopathy.

OBJECTIVE: Inhalant users may develop toluene leukoencephalopathy, a devastating neuropsychiatric disorder. We present a case of toluene-induced damage to the corticospinal and the corticonuclear tracts, which presented with involuntary emotional expression disorder. METHODS: Case study of a 20-year-old man with a 3-year history of frequent solvent abuse was admitted to the Neuropsychiatry Unit of the National Institute of Neurology and Neurosurgery because "he could not speak or walk" but would keep "laughing and crying without reason". RESULTS: Neuropsychiatric examination revealed pathological laughter and crying, facial and speech apraxia, a bilateral pyramidal syndrome, and lack of control of urinary sphincter. Magnetic resonance imaging revealed a highly selective bilateral damage to the pyramidal system and the somatosensory pathway. SPECT imaging showed left fronto-parietal hypoperfusion. CONCLUSIONS: This document provides support for the understanding of involuntary emotional expression disorders as a differential diagnosis in the clinical practice of psychiatrists, as well as the functional anatomy of these conditions.

Vocal Expression of Affective States in Spontaneous Laughter reveals the Bright and the Dark Side of Laughter.

It has been shown that the acoustical signal of posed laughter can convey affective information to the listener. However, because posed and spontaneous laughter differ in a number of significant aspects, it is unclear whether affective communication generalises to spontaneous laughter. To answer this question, we created a stimulus set of 381 spontaneous laughter audio recordings, produced by 51 different speakers, resembling different types of laughter. In Experiment 1, 159 participants were presented with these audio recordings without any further information about the situational context of the speakers and asked to classify the laughter sounds. Results showed that joyful, tickling, and schadenfreude laughter could be classified significantly above chance level. In Experiment 2, 209 participants were presented with a subset of 121 laughter recordings correctly classified in Experiment 1 and asked to rate the laughter according to four emotional dimensions, i.e., arousal, dominance, sender's valence, and receiver-directed valence. Results showed that laughter types differed significantly in their ratings on all dimensions. Joyful laughter and tickling laughter both showed a positive sender's valence and receiver-directed valence, whereby tickling laughter had a particularly high arousal. Schadenfreude had a negative receiver-directed valence and a high dominance, thus providing empirical evidence for the existence of a dark side in spontaneous laughter. The present results suggest that with the evolution of human social communication laughter diversified from the former play signal of non-human primates to a much more fine-grained signal that can serve a multitude of social functions in order to regulate group structure and hierarchy.

Post-stroke emotionalism (PSE): a qualitative longitudinal study exploring individuals' experience with PSE.

PURPOSE: Post-stroke emotionalism (PSE) is a common consequence of stroke characterised by episodes of crying or laughing. There is only one published qualitative study exploring the experience of emotionalism to date. This study aimed to explore individual's experience of PSE and develop a theoretical client-derived framework to shape future psychological interventions. MATERIALS AND METHODS: A primary analysis of the qualitative pseudonymised pre-collected semi-structured interview data of the TEARS study was completed. Participants were recruited from nine acute stroke units in Scotland with participants commencing the study at baseline (two-weeks) and they either continued or dropped out. Interviews were completed at two-weeks, six-months and 12-months post-stroke. RESULTS: Data was analysed from 52 participants at two-weeks, 25 participants at six-months and 23 participants at 12-months. Three major themes were identified: "In the moment," describing characteristics and triggers, "Ways of coping," highlighted a variation of coping strategies including avoidance or acceptance and "Impact," outlining the longer-term effects of PSE such as individuals' beliefs. CONCLUSION: The results indicate specific psychological aspects of PSE which could be viable targets in psychological interventions such as increasing adaptive coping strategies and challenging negatively held beliefs.IMPLICATIONS FOR REHABILITATIONEmotionalism can cause emotional consequences such as distress, embarrassment and fear.Helping individuals to develop insight into triggers for emotionalism could be beneficial to help gain understanding and awareness whereby post-stroke emotionalism (PSE) has the potential to be anticipated and adapted to psychologically.Potential adaptive responses such as acceptance or control and better anticipation of episodes of emotionalism could help to reduce the emotional consequences of PSE.

Emotional authenticity modulates affective and social trait inferences from voices.

The human voice is a primary tool for verbal and nonverbal communication. Studies on laughter emphasize a distinction between spontaneous laughter, which reflects a genuinely felt emotion, and volitional laughter, associated with more intentional communicative acts. Listeners can reliably differentiate the two. It remains unclear, however, if they can detect authenticity in other vocalizations, and whether authenticity determines the affective and social impressions that we form about others. Here, 137 participants listened to laughs and cries that could be spontaneous or volitional and rated them on authenticity, valence, arousal, trustworthiness and dominance. Bayesian mixed models indicated that listeners detect authenticity similarly well in laughter and crying. Speakers were also perceived to be more trustworthy, and in a higher arousal state, when their laughs and cries were spontaneous. Moreover, spontaneous laughs were evaluated as more positive than volitional ones, and we found that the same acoustic features predicted perceived authenticity and trustworthiness in laughter: high pitch, spectral variability and less voicing. For crying, associations between acoustic features and ratings were less reliable. These findings indicate that emotional authenticity shapes affective and social trait inferences from voices, and that the ability to detect authenticity in vocalizations is not limited to laughter. This article is part of the theme issue 'Voice modulation: from origin and mechanism to social impact (Part I)'.

Excessive Laughter-like Vocalizations, Microcephaly, and Translational Outcomes in the Ube3a Deletion Rat Model of Angelman Syndrome.

Angelman syndrome (AS) is a rare genetic neurodevelopmental disorder characterized by intellectual disabilities, motor and balance deficits, impaired communication, and a happy, excitable demeanor with frequent laughter. We sought to elucidate a preclinical outcome measure in male and female rats that addressed communication abnormalities of AS and other neurodevelopmental disorders in which communication is atypical and/or lack of speech is a core feature. We discovered, and herein report for the first time, excessive laughter-like 50 kHz ultrasonic emissions in the Ube3amat-/pat+ rat model of AS, which suggests an excitable, playful demeanor and elevated positive affect, similar to the demeanor of individuals with AS. Also in line with the AS phenotype, Ube3amat-/pat+ rats demonstrated aberrant social interactions with a novel partner, distinctive gait abnormalities, impaired cognition, an underlying LTP deficit, and profound reductions in brain volume. These unique, robust phenotypes provide advantages compared with currently available mouse models and will be highly valuable as outcome measures in the evaluation of therapies for AS.SIGNIFICANCE STATEMENT Angelman syndrome (AS) is a severe neurogenetic disorder for which there is no cure, despite decades of research using mouse models. This study used a recently developed rat model of AS to delineate disease-relevant outcome measures to facilitate therapeutic development. We found the rat to be a strong model of AS, offering several advantages over mouse models by exhibiting numerous AS-relevant phenotypes, including overabundant laughter-like vocalizations, reduced hippocampal LTP, and volumetric anomalies across the brain. These findings are unconfounded by detrimental motor abilities and background strain, issues plaguing mouse models. This rat model represents an important advancement in the field of AS, and the outcome metrics reported herein will be central to the therapeutic pipeline.