Older consumers, who hold trillions of dollars in spending power and make up a growing portion of the global population, would seem to be a prime target for advertisers.

Instead, the demographic is shunned and caricatured in marketing images, perpetuating unrealistic stereotypes and contributing to age discrimination, according to a new report.

More than a third of the United States population is older than 50, but the group turns up in only 15 percent of media images, according to research from AARP, the powerful advocacy organization focused on older Americans. The report, which will be released on Monday at the Advertising Week conference in New York, was based on a random sample of 1,116 images published or posted by popular brands and groups.

More than 53 million people older than 50 are employed, making up a third of the American labor force, according to the Bureau of Labor Statistics. But only 13 percent of the images reviewed by AARP showed older people working.