You can say that people who identify as introverts use more concrete language, but there’s no reliable way to identify intro/extraversion because it’s about as scientific as an internet personality quiz.
Jung’s original definition that some people get energy from socializing while others have to expend energy to socialize doesn’t hold up to scrutiny. We’re social primates and sometimes we like socializing and other times we find it taxing but often it’s a little of both.
If you really don’t like socializing you may have some degree of social anxiety, and maybe you identify as an introvert. Which is fine of course - most people will understand what you mean.
But I think it’s important to remember that we’re not talking about a real thing that actually exists in our genes or brains. It’s just a vague description of your attitude to socializing.
I can’t say for sure whether or not this particular study used proper testing, but as a whole introversion and extroversion is not pseudoscientific.
Jung wasn’t a good scientist, but he did a lot of studies and came up with a lot of theories, some of which happened to be at least partially correct. Also, you seem to be getting something mixed up because Jung defined introversion as an “attitude-type characterised by orientation in life through subjective psychic contents”, and extraversion as “an attitude-type characterised by concentration of interest on the external object”, whereas the more common energy focused definition is not from Jung at all - at least, as far as I am aware.
The big five personality traits, namely openness, conscientiousness, extraversion, agreeableness, and neuroticism have been shown to be consistent, even cross culturally.
There are limitations to that: like how it’s an empirical observation, that other personality traits exist that aren’t factored into those five, or that it’s possible there are a larger number of smaller subfactors that make up those five traits, but ultimately they are scientific.
In addition to Aezora’s response, extrovert vs introvert being a description of your attitude to socializing is only a colloquial use of the term. I am a shy extrovert. I do not get social energy by being alone, like an introvert does, and I have problems talking with new people and even with friends prefer a back seat in the conversation.
Most people seem to fit into more clear buckets, if you believe the marketing, but that doesn’t make the buckets the definition.
