A majority of 57%, from 19,000 people surveyed across 19 countries, said doping has had "a lot" or "some" negative effect on the level of attention they will pay the Games.
Respondents from Germany and the host nation, Brazil, were least affected.
An average of 62% of citizens also said their country's performance has "a lot" or "some" impact on national pride.
Olympic success had the greatest impact on national pride among respondents in emerging economies such as Indonesia, Kenya, Russia, Peru and India.