The visuo-spatial puzzle at right is trickier than it looks, designer Scott Kim warns: "The answers are right in front of you, but they're easy to overlook." Test your skills, following along for hints and insights on how you're exercising your gray matter as you complete this challenge. After all, it's hip to be sharp.
Your parietal lobe, the brain's visual powerhouse, works overtime as the outlines of squares and rectangles seem to jump out at you, explains neuroscientist Richard Restak, who coauthored The Playful Brain with Kim.
Catch yourself poking at the shapes with your finger or pencil? Smart move: "The more sensory avenues you bring into it, the more learning you're doing," Restak adds. Incorporating motion and touch may spark a new engram, a shift in neural tissue that essentially embeds a memory in the brain.