While most Americans say devices like smartphones, cellphones and personal computers have made their lives better and their jobs easier, some say they have been intrusive, increased their levels of stress and made it difficult to concentrate, according to a New York Times/CBS News poll.

Younger people are particularly affected: almost 30 percent of those under 45 said the use of these devices made it harder to focus, while less than 10 percent of older users agreed.

Neil Erickson of Akron, Ohio, blames his lack of focus on his cellphone. “It’s distracting, but you never know if something is going to be important,” he said in a follow-up interview. Mr. Erickson, who is 28 and studying computer engineering, added, “I suppose I could cut down on checking e-mail and phone use, but I probably won’t.”

Technology has simplified life in many ways for Liz Clark, 49, a Realtor from Rye, N.Y., by allowing her to shop online, stay in touch with friends and keep tabs on her three children. “I can text them, and they get back to me immediately,” Ms. Clark said.