Classification of abnormal children: discrimination learning ability.

The team built a single number called a Performance Index. It mixes accuracy, task difficulty, and learning speed.

They tested low-functioning children. The goal was to sort kids by how well they learn new visual tasks.

The index tracked closely with mental age, IQ, and language level. Kids with the same low IQ could still be split into clear learning groups.

The index gave a finer picture than IQ alone. It showed who needs more teaching steps before mastery.

Goharpey et al. (2013) extends this idea. They show Raven’s colored matrices can stand in for the old index when you need a quick, non-verbal estimate.

Bigby et al. (2009) seems to clash. They found working-memory problems are the same in low-IQ and normal-IQ kids with learning disabilities, so IQ splits may not matter. The key difference: W et al. looked at low-functioning kids learning new visual rules, while C et al. looked at memory in mild LD. Different skill, different kids.

Kahn (1992) adds a long view. Early cognitive scores like the Performance Index predict adaptive behavior four years later, giving the index real-world weight.

You can use any quick non-verbal task that gives accuracy, difficulty, and learning rate. Score it once and place the child into a teaching track: fast, standard, or extra steps. Update the track as the child progresses.