When asked to watch a video and press a key each time a black-shirted player passed a basketball, most research participants remained unaware of an umbrella-toting woman strolling across the video screen. This illustrated

The correct answer to the following question will be "Inattention blindness".

Explanation:

Inattentional ignorance or blindness is the inability to recognize an object which is visible but unpredictable because consideration has been paid to the next activity or entity. Almost all of the study respondents were ignorant of a paragliding individual strolling through the projection screen.

Therefore, it's the right answer.