Motion Occlusion Game

About Occlusion

Occlusion shows a short road with a car on the left and a striped wall in the middle. The car drives to the right at a constant speed, goes behind the wall and is no longer visible. You tap the button at the moment you think its front pops out on the other side.

It is a version of the prediction motion task from perception research. All the information is in the part you can see: how fast the car moves, and how wide the wall is. The wall hides the car for between about 0.6 seconds on the early levels and more than three seconds on the highest, and your answer is judged against the moment it would really appear.

How to play

1. Watch the car drive toward the wall and note its speed.
2. Compare the speed with the width of the wall to decide how long it will be hidden.
3. Tap the button, or press the space bar, when you expect the front of the car to come out on the right.
4. The car then continues on its way, so you can see the real moment, and the result note tells you how long it stayed hidden.

A car drives at constant speed and disappears behind a wall. Tap the button at the moment its front pops out on the other side. The car does not slow down or speed up.

How scoring works

The score is based on the difference in milliseconds between your tap and the real exit moment. You receive 100 for a perfect tap and the score falls in a straight line to 0 at the tolerance. The tolerance is 62 percent of the hidden time at level 1 and 34 percent at level 10, never less than 260 ms. For a car hidden for 1.5 seconds on level 1, 0.93 seconds of error is the limit; on level 10 it is 0.51 seconds.

The speed is always constant, the wall is between 90 and 170 pixels wide, and the car is a fixed size. If you do not tap at all, the round ends with 0 points after the car has left the screen.

What it trains

This game trains time-to-contact estimation and the prediction of hidden motion, the same skill that lets you catch a ball that has vanished behind a hand, drive through a tunnel, or know when a person will emerge from behind a wall. It is the basic ability to keep following an object that you can no longer see.

Because speed and distance are combined into a time, it also trains the core relation between rate and duration, and many people find that the skill generalizes well to sport.

Tips for a higher score

• Estimate the speed before the car disappears. Count how fast it moves relative to the width of the wall, for example 'one wall width every two seconds'.
• Keep your eyes on the right edge of the wall, where the car will come out, rather than following the car until it vanishes.
• Tap on your prediction, not on what you see. If you wait until the car appears, you will always be late.
• Do not change your mind midway. Your first estimate is usually best.
• On higher levels the car goes slower and the hidden time is longer. Use a steady count in your head to measure it.

The idea behind it

Prediction motion tasks like this one have been used since the 1970s to study how people estimate time to contact. David Lee's work on the optical variable tau, published in 1976, showed that people and animals can time actions such as braking or catching using the rate of expansion of an object's image.

When an object disappears, the brain keeps simulating its movement. Studies find that estimates are more accurate for short occlusion times and that people tend to be too early for long ones, because attention wanders and the internal clock runs fast under uncertainty. Brain imaging studies suggest that the motion area of the visual cortex stays active while the object is hidden.

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Free, no account. Your best scores are saved on your device.