To test how people react to emotions, you can use film clips which provoke strong reactions. A team of psychiatrists from Ulm University has studied whether older people react like young people to such emotional stimuli, as they supposedly better regulate their emotions. They tested happiness, anger, sadness and disgust. And to trigger disgust, they used... a toilet, of course! Not just any toilet: the "worst toilet in Scotland", as featured in an infamous scene of Trainspotting. In case you haven't seen it:
The scene begins with a young male entering a filthy stall in a public bathroom. After initially feeling repulsed, he decides to relieve himself, but unfortunately loses one of his possessions in the toilet bowl. Determined to retrieve it he reaches his hand and later his arm down the toilet. The scene unfolds in a bizarre fashion showing how the protagonist dives into the toilet bowl and then into the sewage system.
If you are curious about the study: yes, this scene provokes disgust, in all ages. Or in other words, older people (average age 69 years old in the study) weren't any better at containing their disgust when watching it.Image credits: Trainspotting still
More information: Emotion induction in young and old persons on watching movie segments: Facial expressions reflect subjective ratings