Oh, excuse me! Have you ever yawned because somebody else yawned? You aren't especially tired, yet suddenly your mouth opens wide and a big yawn comes out. This phenomenon is known as contagious yawning. And while scientists still don't fully understand why it happens, there are many hypotheses currently being researched. Let's take a look at a few of the most prevalent ones, beginning with two physiological hypotheses before moving to a psychological one. Our first physiological hypothesis states that contagious yawning is triggered by a specific stimulus, an initial yawn. This is called fixed action pattern. Think of fixed action pattern like a reflex. Your yawn makes me yawn. Similar to a domino effect, one person's yawn triggers a yawn in a person nearby that has observed the act. Once this reflex is triggered, it must run its course. Have you ever tried to stop a yawn once it has begun? Basically impossible! Another physiological hypothesis is known as non-conscious mimicry, or the chameleon effect. This occurs when you imitate someone's behavior without knowing it, a subtle and unintentional copycat maneuver. People tend to mimic each other's postures. If you are seated across from someone that has their legs crossed, you might cross your own legs. This hypothesis suggests that we yawn when we see someone else yawn because we are unconsciously copying his or her behavior. Scientists believe that this chameleon effect is possible because of a special set of neurons known as mirror neurons. Mirror neurons are a type of brain cell that responds equally when we perform an action as when we see someone else perform the same action. These neurons are important for learning and self-awareness. For example, watching someone do something physical, like knitting or putting on lipstick, can help you do those same actions more accurately. Neuroimaging studies using fMRI, functional magnetic resonance imaging, show us that when we seem someone yawn or even hear their yawn, a specific area of the brain housing these mirror neurons tends to light up, which, in turn, causes us to respond with the same action: a yawn! Our psychological hypothesis also involves the work of these mirror neurons. We will call it the empathy yawn. Empathy is the ability to understand what someone else is feeling and partake in their emotion, a crucial ability for social animals like us. Recently, neuroscientists have found that a subset of mirror neurons allows us to empathize with others' feelings at a deeper level. (Yawn) Scientists discovered this empathetic response to yawning while testing the first hypothesis we mentioned, fixed action pattern. This study was set up to show that dogs would enact a yawn reflex at the mere sound of a human yawn. While their study showed this to be true, they found something else interesting. Dogs yawned more frequently at familiar yawns, such as from their owners, than at unfamiliar yawns from strangers. Following this research, other studies on humans and primates have also shown that contagious yawning occurs more frequently among friends than strangers. In fact, contagious yawning starts occurring when we are about four or five years old, at the point when children develop the ability to identify others' emotions properly. Still, while newer scientific studies aim to prove that contagious yawning is based on this capacity for empathy, more research is needed to shed light on what exactly is going on. It's possible that the answer lies in another hypothesis altogether. The next time you get caught in a yawn, take a second to think about what just happened. Were you thinking about a yawn? Did someone near you yawn? Was that person a stranger or someone close? And are you yawning right now? (Yawn) (Lip smacking)
O, oprostite! Ste kdaj zazehali, ker je zazehal nekdo drug? Niste posebno utrujeni, a naenkrat na široko odprete usta in močno zazehate. Ta fenomen je znan kot nalezljivo zehanje. Čeprav znanstveniki ne razumejo popolnoma, zakaj se to zgodi, trenutno raziskujejo veliko hipotez. Poglejmo nekaj prevladujočih, začnimo z dvema fiziološkima hipotezama in se nato premaknimo na psihološko. Naša prva fiziološka hipoteza trdi, da nalezljivo zehanje sproži nek določen dražljaj v prvotnem zehanju. Temu se reče fiksiran vzorec obnašanja. Zamislite si fiksiran vzorec obnašanja kot refleks. Zaradi tvojega zehanja zeham še jaz. Podobno kot pri učinku domin zehanje ene osebe sproži zehanje pri osebi blizu, ki je dejanje opazovala. Ko je enkrat ta refleks sprožen, se mora odviti. Ste poskušali ustaviti zehanje, ko se je enkrat začelo? Praktično nemogoče! Druga fiziološka hipoteza je znana kot nezavedna mimikrija, oziroma učinek kameleona. To se zgodi, ko oponašate obnašanje nekoga ne da bi se zavedali, pretanjen in nezaveden manever posnemanja. Ljudje radi posnemamo držo drug drugega. Če sediš nasproti nekoga, ki ima prekrižane noge, boš morda tudi sam prekrižal noge. Ta hipoteza predlaga da zehamo, ko zeha nekdo drug, ker podzavestno posnemamo njegovo ali njeno obnašanje. Znanstveniki verjamejo, da je ta učinek kameleona mogoč zaradi posebnega seta nevronov, znanega kot zrcalni nevroni. Zrcalni nevroni so vrsta možganskih celic, ki se, ko dejanje izvedemo, odzove enako kot takrat, ko vidimo koga drugega izvajati to dejanje. Ti nevroni so pomembni za učenje in samozavedanje. Na primer, ko gledate nekoga, kako nekaj dela, na primer plete ali si nanaša šminko, vam lahko pomaga izvajati ta dejanja bolj pravilno. Nevrološke študije so z uporabo fMRI, funkcionalne magnetne resonance, pokazale, da ko vidimo nekoga zehati ali celo samo slišimo njihovo zehanje, se posebno področje v možganih, kjer so ti zrcalni nevroni, zasveti, kar v nas povzroči odziv z enakim dejanjem: zehanjem. Naša psihološka hipoteza prav tako vključuje delo teh zrcalnih nevronov. Rekli mu bomo sočutno zehanje. Sočutje je zmožnost razumeti, kaj čuti nekdo drug, in deliti njihova čustva, ključna sposobnost za socialno žival, kot smo mi. Pred kratkim so znanstveniki odkrili, da nam pod-set zrcalnih nevronov omogoča vživljanje v čustva drugih na globlji ravni. Znastveniki so odkrili ta sočutni odziv na zehanje med testiranjem prve hipoteze, vzorec fiksiranega dejanja. Ta študija naj bi pokazala, da se pri psih refleks zehanja sproži že samo ob zvoku človeškega zehanja. Njihova študija je to sicer potrdila, a našli so še nekaj zanimivega. Psi so pogosteje zehali ob znanem zehanju, na primer ob lastnikovem, kot pa ob zehanju neznanca. Tej študiji so sledile druge študije na ljudeh in primatih, ki so pokazale, da se nalezljivo zehanje pojavi pogosteje med prijatelji kot med neznanci. Pravzaprav se nalezljivo zehanje začne pojavljati, ko smo stari štiri ali pet let, takrat, ko otroci razvijejo sposobnost prepoznavanja čustev drugih. Medtem ko novejše študije želijo dokazati, da nalezljivo zehanje temelji na moči vživljanja v čustva drugih, je potrebnih več raziskav, da ugotovimo, kaj se pravzaprav dogaja. Možno je, da odgovor leži v povsem drugi hipotezi. Ko naslednjič zazehate, si vzemite trenutek, pomislite kaj se je zgodilo. Ste mislili na zehanje? Je kdo blizu vas zazehal? Je bil to neznanec ali vaš bližnji? Ali sedaj zehate?