A third of U.S. adults in a recent Pew Research Center survey said they'd be "enthusiastic" about a brain chip to enhance their thinking power.

The survey of 4,726 adults examined public attitudes about three emerging technologies that could improve a person's health, cognitive ability or physical capacity.

Responses showed that a majority of American adults are uneasy, or "worried" about all three. But in all three cases, at least a third of respondents were "enthusiastic."

--Using implanted brain chips to boost our thinking power: 69 percent worried vs. 34 percent enthusiastic.

--Editing the genes of babies to eliminate hereditary flaws and diseases: 68 percent worried vs. 49 percent enthusiastic.

--Transfusing synthetic blood to give people much greater speed, strength and stamina: 63 percent worried vs. 36 percent enthusiastic.

"Developments in biomedical technologies are accelerating rapidly, raising new societal debates about how we will use these technologies and what uses are appropriate," said lead author Cary Funk, an associate director of research at Pew, in a statement. "This study suggests Americans are largely cautious about using emerging technologies in ways that push human capacities beyond what's been possible before."

While a majority in the survey say they are worried about human enhancements, 81 percent of U.S. adults expect artificially made organs to be routinely available for transplant in 50 years, and 66 percent of Americans say scientists will probably or definitely cure most forms of cancer by 2066.

More respondents said they would not want enhancements of their brains (66 percent) and their blood (63 percent) than say they would want them (32 percent and 35 percent).

Almost three quarters (73 percent) believe inequality will increase if brain chips become available because initially they will be obtainable only by the wealthy.

Also, 63 percent of Americans think recipients of enhancements will feel superior to those who have not received them.

In the survey, the public is evenly divided on whether these three enhancements are "meddling with nature."

The survey also asked about cosmetic procedures and other current enhancements.

Thirty-four percent say elective cosmetic surgery is "taking technology too far."

The survey was conducted by mail from March 2 to 28 with a margin of error of 2.2 percentage points.

The Pew Research Center also interviewed in focus groups a diverse sample of 47 participants across the country on why they felt uncomfortable about these technologies.

"I just think that there's that place where you're going beyond healthy, you're going to super strength or computer [chip] thinking, [then] I think that's unnatural," said one focus group participant, a 50-year-old woman from Phoenix. "I think that being healthy, productive, [and having a] good quality of life is where I would draw the line."

"If it starts to sound Hitler-like, [trying to create] a perfect specimen of man and woman ... then people who are not perfect might be treated badly," a 59-year-old white woman in Atlanta said.

A 40-year-old Hispanic man in Phoenix was concerned about increased memory. "I hate to sound like a jerk, but I think ... this comes with a certain amount of arrogance when you get this," he said. "Because now you go from being 'normal Dave' in the room to the smartest guy in the room. Being able to – can't have a fight with your wife because you remember every single word that was said because now you have increased memory and everything else. "