Passage: The Coast to Coast AM late night radio talk show helped popularize modern beliefs in shadow people. The first time the topic of shadow people was discussed at length on the show was April 12, 2001 when host Art Bell interviewed Native American elder Thunder Strikes, who is also known as Harley "SwiftDeer" Reagan. During the show, listeners were encouraged to submit drawings of shadow people that they had seen and a large number of these drawings were immediately shared publicly on the website. In October that year, Heidi Hollis published her first book on the topic of shadow people, and later became a regular guest on Coast to Coast. Hollis describes shadow people as dark silhouettes with human shapes and profiles that flicker in and out of peripheral vision, and claims that people have reported the figures attempting to "jump on their chest and choke them". She believes the figures to be negative, alien beings that can be repelled by various means, including invoking "the Name of Jesus".Although participants in online discussion forums devoted to paranormal and supernatural topics describe them as menacing, other believers and paranormal authors do not agree whether shadow people are either evil, helpful, or neutral, and some even speculate that shadow people may be the extra-dimensional inhabitants of another universe. Some paranormal investigators and authors such as Chad Stambaugh claim to have recorded images of shadow people on video.Shadow people feature in two episodes of ITV paranormal documentary series Extreme Ghost Stories, where the phenomenon is described as a "black mass".

Question: What did Art Bell ask listeners to do during his show on April 12,th 2001?
submit drawings of shadow people that they had seen