I stand in awe of the human brain. I hope to keep my mind active, alert, and agile for many years to come. You probably have a similar goal. How can we exercise our gray matter so we can stay at the top of our game? What kind of equipment do we need in out "mental workout" gym?

I'm no expert at the workings of our brains. I'm not sure anyone is. But scientists tell me that brain functions tend to be localized in either left hemisphere (left brain) or the right hemisphere (right brain). There are also full-brain functions that seem to work across both sides. See Science and the Brain for more about current findings.

Left brain functions tend to be verbal, logical, rational, and detail-oriented. Right brain fuctions lean toward the visual, creative, subjective, and seeing the "big picture." Full brain skills involve memory, focus, association, and learning. A complete brain workout program would seem to include exercising all of these areas. Any exercise program must be fun to keep my interest. That's where puzzles come in.

Using my left brain, I'll start by analyzing and listing the various brain functions:

Left Brain		Right Brain
Logical/Sequential		Lateral Thinking
Rational		Intuitive
Objective		Subjective
Analysis		Synthesis
Details		Big Picture
Exact Calculations		Quick Approximation
Lists/Plans		Story/Fantasy
Rules/Procedures		Creative
Spelling/Vocabulary		Visualizing
Control		Pattern Recognition
Language/Verbal Skills		Images/Symbols

Full Brain Facillities  Memory/Recall            Focus    Association            Learning    Speed/Quick Thinking

The icons are shorthand symbols that are displayed in the book after each puzzle’s title to suggest which functions that particular puzzle addresses. If you find that you gravitate toward the left-brain functions, I'd suggest that you make an effort to work on right-brain functions, too. The object is to get a balanced workout. We don't want either side of our brains to get weak. Be sure to throw in some full brain facillities, as well.

Visual thinking is exercised in mazes, rebuses, and many children's puzzles. Verbal skill (and its relative, spelling) are emphasized in riddles, rebuses, codes, and crosswords. Logical and lateral thinking are needed for almost every kind of puzzle. Math and science puzzles often rely on exact calculations and quick approximations. Intuition, creativity, pattern recognition, and synthesis are right-brain functions that lead to "Aha!" moments in the best puzzles. Focus is required for the complex Challenger puzzles at the end of each chapter. Memory and association come into play for crosswords and grouping puzzles especially.

Use the icons in the book to find the puzzles that exercise the functions you want to work. Even when you solve a puzzle with ease, consider reading the solution to see if it presents another approach. Watch how the General Puzzle Principles in each chapter can be applied to make solving easier.