Treatment of pigs has been a political issue in several states due to efforts to pass laws banning the confinement of breeding pigs in gestation crates.
Friedrich said he makes the most headway with state legislators on this issue when he argues that pigs are more cognitively and emotionally advanced than dogs or cats.
"They would recoil in horror if dogs and cats were subjected to the same conditions," he said.
Bob Martin, a food systems expert at the Johns Hopkins School of Public Health, said he developed an appreciation of pigs' emotional complexity while serving recently as executive director of the Pew Commission on Industrial Farm Animal Production.
"Pigs in gestation crates show a lot of signs of depression," he said. "When I went to a farm operation in Iowa where pigs were not confined, they came running up to greet the farmer like they were dogs. They wanted to interact with him."
Bernard Rollin, a Colorado State University professor who teaches both philosophy and animal science, said he expected increasing numbers of meat-eaters to join the ranks of those demanding changes in the way pigs are housed at many large facilities.
"You have to have ideological blindness to think these animals are not intelligent," Rollin said. "I hope we go back to an agriculture that works more with the animals' biological and psychological needs and nature rather than against them."
"The trouble is, we're used to seeing them as herds," he said. "You see 1,000 cows or pigs and think, 'Oh, they're all the same.' But there are actually huge individual differences."
According to Farm Sanctuary, cows become excited over intellectual challenges, chickens can navigate mazes and anticipate the future, and sheep can remember the faces of dozens of individual humans and other sheep for more than two years.
There is existing research suggesting that campaigns such as The Someone Project may make headway in influencing consumers.
In one recent study examining doubts that people might have about eating meat, University of British Columbia psychologists Matthew Ruby and Steven Heine concluded that the animal's level of intelligence was the foremost concern.
Another recent study by university researchers from Australia and Britain concluded that many meat-eaters experience moral conflict if reminded of the intelligence of the animals they are consuming.
"Although most people do not mind eating meat, they do not like thinking of animals they eat as having possessed minds," the researchers wrote in Personality and Social Psychology Bulletin.
Dena Jones, manager of the Animal Welfare Institute's farm animal program, predicted that public awareness of farm animals' intelligence would steadily increase, leading to more pressure on the farm industry from food retailers and restaurant chains.
"It's the retailers who are going to force the industry to bring their practices into line with consumer expectations," she said.
Janeen Salak-Johnson, a professor in the University of Illinois animal sciences department, said she observes a conflict among her students as they contemplate issues related to animal welfare and food supply. While some students from suburban Chicago may be embracing meatless diets, students from farming communities are convinced that local farms help feed the world.
Salak-Johnson says she favors a "happy medium" and contends that campaigns such as The Someone Project go too far in trying to equate "production animals" with household pets.
"We can't let all these animals roam free — it's not an economically sustainable system," she said. "Yes, we have to fulfill our obligations to these animals, but is it fair for us to starve the world?"
Poll: What's your favorite of the top 10 pizza toppings (according to a recent survey)?