Many mortgage-holders still do not understand basic aspects of how mortgage products work, according to the ESRI.
The Economic and Social Research Institute also says consumers make better long-term decisions about mortgages after reading official advice on switching.
Its Behavioural Research Unit conducted a controlled experiment funded by the Competition and Consumer Protection Commission (CCPC).
In it, a representative sample of mortgage-holders answered questions about how mortgages work - and listed what they thought they need to do if they wanted to switch.
Responses given before reading CCPC's online advice were compared to responses afterwards.
The results showed that mortgage-holders were initially drawn to high cashback offers that are ultimately more expensive.
For instance, on average, consumers preferred €2,200 in cashback to a 0.4% better APR.
Yet, for the average mortgage, this amounts to taking out a loan for €2,200 at 24% interest.
After reading the official advice, consumers placed much more weight on APR and the long-term savings they could make.
They also became more confident about picking good deals.
The ESRI says: "The experiment therefore supports new regulations introduced in 2019, which require lenders to direct consumers to this advice."
It also revealed potentially serious misunderstandings.
When asked what they would need to do to switch, just one-third realised that they would need a solicitor and one-quarter that they would need to have the property re-valued.
Most consumers did also not understand one or more basic aspects of mortgage products.
Examples included how repayments relate to the cost and length of a mortgage, the implications of paying only interest or the extent of debt liability.
Fergal O'Leary is a member of the CCPC: "The results provide valuable insights into consumer decision-making and we have refined the information we give to consumers as a result.
"The research clearly shows that it is worthwhile to take some time to review the independent information.
"This is the case for first time buyers but equally so for many consumers who could save on their mortgage by switching.
"Taking a few minutes to check ccpc.ie can help consumers cut through the advertising material and allow them to get the best deal for their needs."
Dr Shane Timmons of the ESRI's Behavioural Research Unit adds: "Cashback can be useful, but in our experiment consumers placed too much weight on it until they read the advice.
"Generally, most people are better off securing long-term savings from a lower APR."