What's Your IQ

YOUR STAIRCASE

The flash shrinks until you start guessing

Two right in a row and the flash gets shorter. One wrong and it gets longer. It settles where you're right about 70% of the time — your inspection time.

rightwrongBar height = flash length

Play the game above to draw your staircase.

Why the stripes matter

Without the striped cover, the image lingers on your retina for a fraction of a second after it's gone — an afterimage. The "mask" wipes that out, so the flash lasts exactly as long as we say.

Try both. With no mask, even a very short flash is easy.

NO MASK

The afterimage gives you extra time.

WITH MASK

The stripes cut the image off cleanly.

INSIDE YOUR BRAIN

Pure seeing speed

Because you can take your time answering, movement speed drops out. What's left is how quickly the visual system builds a usable picture.

Based on Gray's Anatomy, fig. 728 (public domain)

−0.5correlation with IQ

Across many studies, shorter inspection times go with higher IQ scores — one of the most reliable links between a simple perceptual task and intelligence.

Grudnik & Kranzler, 2001

1972Vickers' lines

Doug Vickers introduced the two-line "pi" figure — the same shape used in this game — to measure visual intake time without any need to move quickly.

Vickers, Nettelbeck & Willson, 1972

SourcesVickers, Nettelbeck & Willson (1972), PerceptionGrudnik & Kranzler (2001), IntelligenceDeary (2000), Looking Down on Human Intelligence

WHAT THIS GAME TRAINS

How fast your eyes take things in

Two lines flash for a few hundredths of a second, then get masked. Which was longer? There's no rush to answer: it measures how quickly you take in information, not how quickly you move.

corestrongsomelight

corePerceptual speedTaking in a display in tens of milliseconds.

strongVisual discriminationJudging which line is longer.

someAttention timingBeing ready at the moment of the flash.

someDecision confidenceChoosing well when the image was very brief.

BEYOND THE SCREEN