The task
Sort 64 cards to match either
- colour rule (red, blue, yellow or green)
- form rule (crosses, circles, triangles or stars)
- number rule (one, two, three, or four figures)
The sorting rule changes without notice
Requirement
- Monitor for rule changes
- Shift sets accordingly
- Sort cards following the new sorting rule
Scoring (most common)
- Set shifting (flexibility) difficulties indicated by total number of preservative errors