Driving across a lightly-traveled bridge on your way to work early one morning, you are the only one on the road when a car comes toward you, skidding out of control. The car careens up against a concrete guardrail and assumes a precarious, almost-upright position overlooking the icy waters below. The driver crashes through the windshield, and as his bloody body lies on the hood of the demolished automobile, you assess the horrifying situation. If you don't help this stranger, he will surely die. But with pieces of the guardrail missing from the impact of the crash, helping this person -- who easily outweighs you by 100 pounds -- could cause you and the victim to plunge into the bay below the bridge. Without any means of calling for help, you are left to your own devices. What do you do?

We can all idealize or project our behavior in a given situation. But how well do we really know ourselves? When push comes to shove, will we risk our lives, stand up for our rights, or throw caution to the wind for love? How often do we act in accordance with our idealized sense of ourselves? How often does our outward behavior or demeanor differ from the person who lurks within?

We all have our "off" moments, of course. But if you'd like to gain a sense of how you might behave during life's most critical moments, this month's Mind-Brain Lab is for you. Based on the best-selling HarperSanFransisco book, Who Do You Think You Are? Explore Your Many-Sided Self With the Berkeley Personality Profile by Keith Harary, Ph.D. and Eileen Donahue, Ph.D., this month's exercise offers you the opportunity to explore the ways in which your personality might influence your behavior in plausible, life-altering situations such as scale-topping earthquakes and nuclear holocaust. Each scenario will allow you to delve into particular aspects of your personality, from your intellectual style to your expressive and interpersonal self. As you actively compare your personal ideals to the reality of how you might behave in a variety of real-life scenarios, you may be surprised by the person you discover within. If a friend, colleague, or loved one joins in these scenarios, you may gain some insight into how others see you as well.