Final answer:
Pablo Picasso is credited for pioneering the use of nonrepresentational imagery in modern painting with his Cubist paintings.
Step-by-step explanation:
Pablo Picasso is credited for pioneering the use of nonrepresentational imagery in modern painting. In 1907, he painted Les Demoiselles d'Avignon, which is considered one of the first Cubist paintings. Cubism, co-founded by Picasso and Georges Braque, broke away from representational art and analyzed objects by breaking them up and reassembling them in abstracted forms from multiple viewpoints. This approach revolutionized the way space was depicted in painting and had a significant impact on modern art.