Tag Archives: muscoli

The Carney Landis Experiment

Suppose you’re making your way through a jungle, and in pulling aside a bush you find yourself before a huge snake, ready to attack you. All of a sudden adrenaline rushes through your body, your eyes open wide, and you instantly begin to sweat as your heartbeat skyrockets: in a word, you feel afraid.
But is your fear triggering all these physical reactions, or is it the other way around?
To make a less disquieting example, let’s say you fall in love at first sight with someone. Are the endorphines to be accounted for your excitation, or is your excitation causing their discharge through your body?
What comes first, physiological change or emotion? Which is the cause and which is the effect?

This dilemma was a main concern in the first studies on emotion (and it still is, in the field of affective neurosciences). Among the first and most influential hypothesis was the James-Lange theory, which maintained the primacy of physiological changes over feelings: the brain detects a modification in the stimuli coming from the nervous system, and it “interprets” them by giving birth to an emotion.

One of the problems with this theory was the impossibility of obtaining clear evidence. The skeptics argued that if every emotion arises mechanically within the body, then there should be a gland or an organ which, when conveniently stimulated, will invariably trigger the same emotion in every person. Today we know a little bit more of how emotions work, in regard to the amygdala and the different areas of cerebral cortex, but at the beginning of the Twentieth Century the objection against the James-Lange theory was basically this — “come on, find me the muscle of sadness!“

In 1924, Carney Landis, a Minnesota University graduate student, set out to understand experimentally whether these physiological changes are the same for everybody. He focused on those modifications that are the most evident and easy to study: the movement of facial muscles when emotion arises. His study was meant to find repetitive patterns in facial expressions.

To understand if all subjects reacted in the same way to emotions, Landis recruited a good number of his fellow graduate students, and began by painting their faces with standard marks, in order to highlight their grimaces and the related movement of facial muscles.
The experiment consisted in subjecting them to different stimuli, while taking pictures of their faces.

At first volunteers were asked to complete some rather harmless tasks: they had to listen to jazz music, smell ammonia, read a passage from the Bible, tell a lie. But the results were quite discouraging, so Landis decided it was time to raise the stakes.

He began to show his subjects pornographic images. Then some medical photos of people with horrendous skin conditions. Then he tried firing a gunshot to capture on film the exact moment of their fright. Still, Landis was having a hard time getting the expressions he wanted, and in all probability he began to feel frustrated. And here his experiment took a dark turn.

He invited his subjects to stick their hand in a bucket, without looking. The bucket was full of live frogs. Click, went his camera.
Landis encouraged them to search around the bottom of the mysterious bucket. Overcoming their revulsion, the unfortunate volunteers had to rummage through the slimy frogs until they found the real surprise: electrical wires, ready to deliver a good shock. Click. Click.
But the worst was yet to come.

The experiment reached its climax when Landis put a live mouse in the subject’s left hand, and a knife in the other. He flatly ordered to decapitate the mouse.
Most of his incredulous and stunned subjects asked Landis if he was joking. He wasn’t, they actually had to cut off the little animal’s head, or he himself would do it in front of their eyes.
At this point, as Landis had hoped, the reactions really became obvious — but unfortunately they also turned out to be more complex than he expected. Confronted with this high-stress situation, some persons started crying, others hysterically laughed; some completely froze, others burst out into swearing.

Two thirds of the paricipants ended up complying with the researcher’s order, and carried out the macabre execution. In any case, the remaining third had to witness the beheading, performed by Landis himself.
As we said, the subjects were mainly other students, but one notable exception was a 13 years-old boy who happened to be at the department as a patient, on the account of psychological issues and high blood pressure. His reaction was documented by Landis’ ruthless snapshots.

Perhaps the most embarassing aspect of the whole story was that the final results for this cruel test — which no ethical board would today authorize — were not even particularly noteworthy.
Landis, in his Studies of Emotional Reactions, II., General Behavior and Facial Expression (published on the Journal of Comparative Psychology, 4 [5], 447-509) came to these conclusions:

1) there is no typical facial expression accompanying any emotion aroused in the experiment;
2) emotions are not characterized by a typical expression or recurring pattern of muscular behavior;
3) smiling was the most common reaction, even during unpleasant experiences;
4) asymmetrical bodily reactions almost never occurred;
5) men were more expressive than women.

Hardly anything that could justify a mouse massacre, and the trauma inflicted upon the paritcipants.

After obtaining his degree, Carney Landis devoted himself to sexual psychopatology. He went on to have a brillant carreer at the New York State Psychiatric Institute. And he never harmed a rodent again, despite the fact that he is now mostly remembered for this ill-considered juvenile experiment rather than for his subsequent fourty years of honorable research.

There is, however, one last detail worth mentioning.
Alex Boese in his Elephants On Acid, underlines how the most interesting figure of all this bizarre experiment went unnoticed: the fact that two thirds of the subjects, although protesting and suffering, obeyed the terrible order.
And this percentage is in fact similar to the one recorded during the infamous Milgram experiment, in which a scientist commanded the subjects to inflict an electric shock to a third individual (in reality, an actor who pretended to receive the painful discharge). In that case as well, despite the ethical conflict, the simple fact that the order came from an authority figure was enough to push the subjects into carrying out an action they perceived as aberrant.

The Milgram experiment took place in 1961, almost forty years after the Landis experiment. “It is often this way with experiments — says Boese — A scientis sets out to prove one thing, but stumbles upon something completely different, something far more intriguing. For this reason, good researchers know they should always pay close attention to strange events that occur during their experiments. A great discovery might be lurking right beneath their eyes – or beneath te blade of their knife.“

On facial expressions related to emotions, see also my former post on Guillaume Duchenne (sorry, Italian language only).

Senza pelle

He Took His Skin Off For Me (2014) è il saggio di diploma firmato dal giovane Ben Aston alla prestigiosa London Film School, realizzato anche tramite una campagna Kickstarter che ha coperto l’intero budget relativo agli effetti speciali (più di 9.000 sterline).

Il cortometraggio è una favola surreale e macabra incentrata su un rapporto sentimentale fondamentalmente in disequilibrio: il racconto del sacrificio, accettato per amore dal protagonista, procede con toni delicati nel mostrare come le piccole difficoltà domestiche divengano sempre più problematiche con il passare del tempo. Come il sangue imbratta via via ogni superficie della casa pulita, così ogni minima azione (eseguita o mancata) lascia tracce nei sentimenti dei personaggi, nella loro intimità, nella loro vita emotiva.

Il concept, semplice e diretto, si arricchisce quindi di molti livelli di lettura: vi si può scorgere una parabola sui rischi di mettersi completamente a nudo di fronte a una persona, quando quest’ultima non fa lo stesso con noi; una storia sui compromessi necessari per restare vicini; perfino la versione horror di una relazione morbosa e votata fin dall’inizio al fallimento. Come ha dichiarato il regista, “quando le persone mi dicono cosa pensano che significhi, spesso rivelano anche una parte di loro stessi. Il potere dell’allegoria è il suo essere sfaccettata. Ogni spettatore ha il suo punto di vista; simpatie e significati mostrano di andare quasi in ogni direzione“.

Ecco il sito ufficiale del cortometraggio, in cui potete trovare anche backstage e altri materiali.

Il volto e l’emozione

Quando nel 1806 Guillaume-Benjamin Duchenne nacque a Boulogne in una famiglia di umili pescatori, la prima cosa che fece sua madre, stringendolo al petto, fu sorridere. Non poteva sapere che il sorriso che le illuminava il volto sarebbe stato chiamato dagli studiosi sorriso Duchenne, proprio in onore di suo figlio.

In realtà, oltre che al sorriso, il nome Duchenne è ancora oggi legato a varie atrofie, distrofie e paralisi muscolari da lui individuate e studiate, così come a uno strumento chirurgico per l’asportazione di campioni di tessuti vivi da lui inventato: ma la sua fama è legata principalmente alle ricerche sulla neurofisiologia dell’emozione. Partendo dalle ricerche galvaniche, Duchenne mise a punto uno stimolatore elettrico faradico che, applicato a determinati punti della pelle, stimolava i muscoli sottostanti con enorme precisione. Praticamente questa tecnica (non invasiva) si basava sull’uso di elettrodi molto appuntiti che appoggiati all’epidermide facevano passare una piccola scossa elettrica, indolore ed estremamente localizzata. In questo modo riuscì a catalogare per primo tutti i muscoli della faccia umana, e non soltanto.

Utilizzando soggetti paralizzati, per essere sicuro che nessun movimento fosse volontario, Duchenne cominciò ad interessarsi al modo in cui i muscoli facciali vengono utilizzati per trasmettere emozioni. A seconda che siamo arrabbiati, felici, annoiati, spaventati, il nostro volto esprime questi stati d’animo con un complesso insieme di movimenti muscolari; Duchenne riuscì a “comporre” e catalogare queste espressioni emozionali con il suo apparecchio stimolatore ed essendo un appassionato di fotografia riuscì anche a documentare queste ricerche con una eccezionale serie di immagini.

Questo suo studio sulla fisiologia muscolare durò vent’anni, la missione di una vita. Fra le varie sorprese incontrate nel corso degli esperimenti, Duchenne trovò anche qualcosa che, per quanto non abbia un profondo valore scientifico, è rimasta una delle scoperte più curiose legate alla sua ricerca: la differenza fra un sorriso sincero e uno falso.

Duchenne si accorse che, quando stimolava elettricamente i suoi soggetti, non riusciva a ottenere da loro un sorriso convincente. Cosa mancava? Provò quindi a provocare con gli elettrodi un sorriso sul volto di un soggetto, e immediatamente dopo apostrofarlo con una battuta spiritosa, per confrontare quali muscoli si muovessero nel sorriso “indotto” e in quello spontaneo. E di colpo, capì.

Quando sorridiamo per cortesia (ma in realtà siamo annoiati), oppure per ingannare chi ci guarda facendogli credere che siamo felici, tutti i muscoli attorno alla bocca si attivano in maniera molto simile al sorriso naturale. Questo sorriso “bugiardo” difetta però di qualcosa:  sono i muscoli intorno agli occhi e alle sopracciglia, scoprì Duchenne, che si muovono soltanto se il sorriso è sincero e genuino. Provò quindi che il detto “ridere con gli occhi” era meno metaforico del previsto.

Nonostante i suoi metodi poco ortodossi, Duchenne rivoluzionò la conoscenza scientifica: è ricordato come uno dei più grandi medici del XIX Secolo e come il fondatore della neurologia. Se lo sapesse sua madre, come credete che sorriderebbe?

(Grazie, Marco!)