Daniel Gilbert, a professor at Harvard University and author of a New York Times bestselling novel, presented aspects of mental simulation on Friday as the Department of Psychological & Brain Sciences’ 2009 John T. Lanzetta lecturer.

Mental simulation is the way we imagine scenario outcomes in our mind without actually experiencing them. In this way, people can make decisions without having prior experience in the exact same situation.

For example, we need not have actually worked in law in order to image what life would be like as a lawyer. However, Gilbert highlighted four main reasons why mental simulations are imperfect guides.

The first reason is that people tend to imagine very unrepresentative simulations. Studies show that people are more likely to remember the most unlikely events rather than the most common outcomes, because extreme cases are more memorable. Even though most dental visits are fairly innocuous, most people still fear the dentist, because they instinctively remember the one time the dentist pulled out a tooth. In those cases, simulations will be based on unlikely events because that comes to mind first.

Simulations also tend to essentialize events and ignore the ancillary details, which have been shown to make a difference in predicting people’s actual reaction to an event. Remembering the driving, parking and waiting involved in a dentist appointment instead of just imagining the time spent in the dentist’s chair can have ameliorative effects.

Another aspect of simulation that results in its negative disposition is truncation. After a negative or positive event happens, people’s coping skills and active adaptation ability kick in and they immediately feel better. However, as this is not part of the initial reaction, people do not account for what happens after the event and do not include it in their simulation. In this way, people overestimate their own devastation in the face of a rejection or other disappointment.

Lastly, simulations are biased based on comparisons people make, even though those expectations disappear once people are actually in the experience. For example, a person predicting how much he would enjoy eating potato chips after being exposed to chocolate underestimates his enjoyment because his simulation includes a comparison.

While eating the chips, the person only pays attention to the taste of the chips in his mouth and does not consider the chocolate he is not eating, so contrary to his prediction, his rating of his enjoyment while eating the chips equals the rating of someone who does not make such a comparison.

Gilbert suggested a remediation method of simply asking others how much they enjoy their experience. His studies found that asking others in this “surrogation” technique halves the error from simulation predictions even when given ample background information. He suggested that people are much more similar in likes and dislikes than most people would like to believe.

When asked the purpose of having such faulty and misleading simulation mechanism in our brain, Gilbert replied modeling his response after Winston Churchill, “Simulation is the worst method of prediction except for all the others…. For what it’s worth, simulations get you closer to your goal than random guessing.”