Question

read the paragraph. researchers at harvard university wanted to learn more about how people notice things. so they invited a group of volunteers to take part in an experiment. these participants were shown a video of a group of basketball players. then, the participants were told to count the number of times the players tossed the basketball back and forth. who were the participants in this experiment? complete the sentence. the participants were ▼ who ▼ the experiment by ▼.

Explanation:

The answer is directly extracted from the text: "they invited a group of volunteers to take part in an experiment" which identifies the participants and their action related to the experiment.

Answer:

The participants were a group of volunteers who took part in the experiment.