60 percent of people in the US are worried about how much companies know about them

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Do you find it useful or creepy when you go into a store and later check your cell phone and an ad from that same store appears?

Giving information to companies about where we are, what we like doing and who our friends are is a problem for many in the U.S., according to data from Kantar TNS.

Sixty percent of U.S. consumers are concerned about the amount of information that companies know about them, according to Kantar's "Connected Life" study, which surveyed 70,000 people in 56 countries.

Attitudes to personal data and privacy varies around the world, making marketers' jobs more difficult. While, on average, 40 percent of people globally are concerned about the amount of personal information a brand has about them, this rises to 50 percent or more in regions including Northern and Western Europe, Latin America and developed Asian countries, as well as in the U.S.

Global study reveals consumers opinions on brand trust vary
Global study reveals consumers opinions on brand trust vary

Michael Nicolas, global lead of connected solutions at Kantar TNS, said people are suspicious rather than accepting of companies' access to personal information in the developed world. "The connection that brands have strived to have with consumers — whether reaching them through new technologies, sharing brand content, targeting them based on their personal data or widening the scope of ecommerce — appears to be eroding trust, not building it," he said in an emailed statement.

It's a different picture in emerging markets, where new technology and social media are still seen as empowering, the report suggests. In the U.S., 50 percent of people are concerned about how social networks control what they see in their feeds, while in emerging Asian markets this figure is only 27 percent.

People are also worried about how much connected devices such as digital assistants are gathering information about them. Forty-three percent of consumers globally say they object to these devices monitoring their activities, even if it makes their lives easier, but this figure drops to 35 percent in emerging Asian countries.

This trade-off between privacy and convenience is a delicate one, especially with digital assistants that have to process sound all the time, waiting for a "wake word" or phrase, such as "OK Google."