The Invisible Gorilla: B2 English Lesson

This B2 English lesson on the invisible gorilla explores how focused attention can make an obvious event disappear. Practice the past simple and past continuous for narration and build vocabulary for attention, awareness, and distraction.

Vocabulary

READ · LISTEN · NOTICE

The Invisible Gorilla

Read at your own pace, or play the audio and follow the passage. Listen again without reading for additional practice.

Imagine watching a video of two teams passing basketballs. Your task is to count the passes made by one team. While you are counting, a person in a gorilla costume walks through the players, stops briefly, beats their chest, and leaves. The gorilla is fully visible, yet many viewers do not report seeing it.

The original experiment

In 1999, psychologists Daniel Simons and Christopher Chabris studied how people notice unexpected events while completing another visual task. Participants watched short videos of two teams passing a basketball and counted passes by either the white team or the black team. During the video, an unexpected person crossed the scene. In one version, that person wore a gorilla costume. Across the study’s conditions, a substantial number of participants overlooked the unexpected event. Detection changed according to what participants were counting and how similar the unexpected person was to the team receiving their attention.

Inattentional blindness

Psychologists call this effect inattentional blindness: failing to notice an unexpected but visible object while attention is absorbed by another task. The limit concerned attention rather than basic eyesight. Counting passes required viewers to select certain movements and ignore others. That selective process helped them complete the assigned task, but it also made an unrelated event easier to miss. Something can therefore be conspicuous and still remain outside a person’s awareness.

Expertise does not remove the limit

A separate 2013 study tested 24 radiologists while they were searching chest CT scans for lung nodules. Researchers Trafton Drew, Melissa Võ, and Jeremy Wolfe placed a gorilla image in the final scan. It was 48 times larger than the average nodule. Eighty-three percent of the radiologists did not report it, and eye tracking showed that most of those who missed it had looked directly at its location. The result does not mean that the radiologists were careless or unable to find nodules. The gorilla was not part of the task they had been given. The study instead shows that expertise does not make attention unlimited. Focus supports accurate work on a defined goal, but it does not guarantee awareness of every visible detail.

Adapted from Simons and Chabris (1999), “Gorillas in Our Midst: Sustained Inattentional Blindness for Dynamic Events” and Drew, Võ, and Wolfe (2013), “The Invisible Gorilla Strikes Again: Sustained Inattentional Blindness in Expert Observers”.

GRAMMAR FOCUS

Narrative Tenses (Past Simple vs Past Continuous)

subject + was / were + verb-ing; subject + past simple verb

Use the past continuous for an action already in progress and the past simple for a completed event during it. Use two past continuous clauses when both actions were in progress at the same time.

1. Setting the scene with the past continuous

   “At eight o’clock, we were waiting outside the theater.”

   “A cold wind was blowing across the empty platform.”

2. A completed event during an ongoing action

   “While the viewers were counting passes, a gorilla walked onto the court.”

   “I was making soup when the doorbell rang.”

3. Two actions in progress together

   “While I was packing, my sister was checking the train times.”

   “The chef was chopping vegetables while the assistant was washing the dishes.”

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Discuss the ideas

Work through the discussion questions on your own, or with a teacher or partner.

1. Have you ever failed to notice something obvious because you were focused on something else?
2. Why do you think confidence in what we saw doesn’t guarantee we saw it accurately?
3. Where in daily life—driving, using a phone, working—do you think inattentional blindness is most dangerous?
4. Can you think of a job where noticing the unexpected matters as much as completing the main task?
5. Does knowing about the invisible gorilla experiment change how much you trust your own attention?

What this invisible gorilla English lesson developed

In this B2 English lesson on the invisible gorilla, you learned how completely attention can hide something in plain sight, built vocabulary for attention and noticing, and used the past simple and past continuous to narrate what was happening when something occurred.

Read more: The Invisible Gorilla by Christopher Chabris and Daniel Simons, the psychologists behind the original experiment, who explore how confidently we trust our own attention, memory, and perception—and how often that confidence is misplaced.

Next lesson: Continue with Memory Is Reconstruction to examine how attention and later knowledge shape what people remember.

About these B1–C2 English lessons · Browse all B1–C2 lessons

CONTINUE PRACTICING

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Turn this lesson into a class-ready sequence with vocabulary and past-simple/past-continuous practice, the complete reading and a varied reading check, short listening practice, and four TOEFL Interview questions about attention. A focused tip develops complete responses to multipart questions, with later models and brief teacher notes on timing and objectives.

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