Biology: Stroop test?

Nowadays, the ability to concentrate is declining due to strong media influences and distractions.

The classic Stroop test is often used to assess concentration, among other things. Explain how the test works. Conduct a series of experiments (e.g., using a suitable online test) and describe the procedure and the variables collected (and any other possible variables). First, determine your learning curve (at least 5 trials) and present it. (5 points)

Can someone explain the task to me? Thank you.