Final answer:
Scientists would likely be happy seeing monkeys independently work on puzzles, as it indicates their ability for cognitive learning and abstract thought, relevant to studies like those by Wolfgang Köhler with chimps.
Step-by-step explanation:
When the monkeys started working on the puzzles on their own, the scientists were likely happy as this behavior demonstrated cognitive learning and problem-solving abilities, showing that the monkeys could solve puzzles without direct intervention, implying a capacity for abstract thought.
Classic work on cognitive learning by Wolfgang Köhler with chimps showed that these primates were capable of using tools and abstract thought to reach a goal, like obtaining a banana beyond their immediate grasp. This runs parallel with the idea that scientists working with monkeys and seeing them engage autonomously in puzzle-solving would be pleased by such advanced cognitive display.