It’s a hot summer day when you notice an Italian ice cream parlor. At first you resist the temptation since you’ve committed to a healthy diet. But as you get closer, you find your hand reaching for your wallet. “Two scoops of vanilla, please.” At home you confess your sin, but since you can’t come up with a good reason, you simply mumble, “The devil made me do it.”
The metaphor of the devil is perhaps not as far fetched as it may seem. We are often moved by subconscious impulses that we may not be fully aware of. Human behavior is complex and rarely, if ever purely rational. But, behavior doesn’t happen by chance or out of the blue.
The behavior of any animal is triggered by various stimuli in its environment. Behavior can be physical or mental, conscious or subconscious, inherited or learned, and voluntary or involuntary. In this way all organisms, including humans, are like machines—we receive an input from our environment (a stimulus) and we respond with an output (a behavior). Most behavior has a genetic component, for example we are all drawn toward food and away from pain. Human behavior can also be influenced by our cultural norms, our beliefs and biases, and social factors such as authority, persuasion, and coercion, making it significantly more complex than the behavior of non-humans. Still every behavior is a response to a stimulus, with the intention to optimize benefit and minimize harm (even if sometimes they don't work out as we intended, see bias). Because so many factors go into determining behavior, a large part of any behavioral response occurs on a level below our conscious awareness. You don't consciously think, "I must pull my hand away from this rattlesnake," you just do it. This system works magnificently well; after all it has preserved life on this planet for a long time.
The brain is not a unified whole, but more like a “band of rivals,” each part lobbying for its own agenda. One example is the ice cream shop dilemma, in which the desire for calories fights it out with the desire to look good. Another example is the push and pull between selfish and pro-social behavior. Our culture promotes pro-social behavior. Being perceived as selfish is not too endearing, but, it’s no secret that as April fifteenth approaches most of us would like to find ways to minimize our tax payments rather than just opening our check-book.