In ka badan 40 sano, Paul Ekman ayaa taageeray aragtida ah in shucuurta aadanaha ay yihiin kuwo gooni ah, la qiyaasi karo, iyo physiologically kala duwan. shaqada ugu saameynta badan Ekman ee ku wareegsan helitaanka in shucuurta qaarkood u muuqday in ay si caalami ah loo aqoonsan yahay, xitaa in dhaqamada in ay ahaayeen preliterate oo aan awoodin in ay barteen ururada for muuqaalada wajiga iyada oo loo marayo warbaahinta. Daraasad kale oo classic ogaaday in marka ka qaybgalayaashu ay murqaha wajiga ay ku qaloocan muuqaalada wajiga kala duwan (tusaale ahaan, naxdin), waxay soo sheegeen waayo-aragnimooyinka physiological iyo subjective in kulan muuqaalada wajiga kala duwan. Natiijooyinka cilmi-baaris uu keentay inuu kala saaro lix dareen sida: cadho, naxdin, cabsi, farxad, murugo iyo yaabi. Later in uu xirfadiisa, Ekman ku taageeray aragtida ah in shucuurta kale ee caalamiga ah laga yaabi karaa ka baxsan
xanaaq iyo naxdin