'research into' vs 'research on'

Question

I'm working on a book called 'Academic Vocabulary in Use' published by Cambridge University Press. There's a lesson suggesting some nouns commonly associated with particular prepositions. Research is one of them and shown to be followed by either 'into' or 'on'. However, in the piece of exercise below, there is only one correct answer:

I went to an interesting presentation on research into aspects of the human brain. The speaker began by saying that the rationale for/behind his investigation was the need to better understand the ageing process.

For those having two correct answers, both would be shown (as in 'rationale for/behind'). It means on can't follow 'research' in this case. After looking up the word 'research' in different dictionaries, I got no explanation for the difference between 'research on and research into. They are even used interchangeably in an example offered by Cambridge Dictionary:

They are carrying out/conducting/doing some fascinating research into/on the language of dolphins.

Cambridge Dictionary

Then, is there any difference between 'research on' and 'research into'?

Answer 1

“Research into” suggests you’re researching information that is already out there—reading published studies, watching news reports, combing through websites, etc.

“Research on” suggests you are conducting primary research to find new information—interviewing people, science experiments, quantitative/qualitative analysis, etc.

Examples:

“My research into the university’s recent news highlights its extensive community outreach”

Research “on” wrongly hits the ear here because it can sound like you’re stupidly attempting to say you put together this news yourself, when the sentence makes it clear you did not.

“My research on the reception of the university’s recent PR campaign suggests it is working”

This sentence tells the reader that you are talking to the university’s audiences yourself and analyzing responses to form a conclusion.

There are probably certain sentences where you can use “research into” and “research on” interchangeably, but keeping the above shortcuts in mind can help eliminate ambiguity.