A simultaneous discrimination procedure for the measurement of vision in nonverbal children.

Researchers needed a way to test eyesight in kids who could not name letters or talk. They built a simple box with two windows. One window showed black and white stripes. The other stayed gray.

The child pointed to the stripes. If the guess was right, a toy lit up and played music. The stripes got thinner each time. The team worked with eleven nonverbal children, most with autism.

Eight of the eleven children finished the whole test in one to three short visits. Their final stripe width matched, or beat, the score from a regular eye chart.

Kids stayed on task because the toy gave instant reward. No tears, no drops, no speech needed.

Whiting et al. (2015) later used the same fade-in trick to teach fine visual matches to adults with severe ID. They moved from testing eyesight to training new discriminations, showing the method can both measure and teach.

Ganz et al. (2004) hit a wall with standard prompting until they tilted the cards 45°. Their tweak reminds us that tiny physical details matter when you fade stimuli.

Stevenson et al. (2025) scoured thirteen newer studies and found no off-the-shelf autism test for kids with visual loss. The 1977 box still stands as one of the few ready tools that work without words.

You can copy this box in one afternoon. Two pieces of cardboard, a printer, and a dollar-store toy are enough. Run the same fade-in sequence before you write goals for reading or matching. If the child can see the stripes, your later errorless teaching will stick. If not, you just saved weeks of pointless trials.