Daniel Gilbert

This general finding–that information acquired after an event alters memory of the event–has been replicated so many times in so many different laboratory and field settings that it has left most scientists convinced of two things.6 First, the act of remembering involves ‘filling in’ details that were not actually stored; and second, we generally cannot tell when we are doing this because filling in happens quickly and unconsciously.7 Indeed, this phenomenon is so powerful that it happens even when we know someone is trying to trick us.

When we have an experience–hearing a particular sonata, making love with a particular person, watching the sun set from a particular window of a particular room–on successive occasions, we quickly begin to adapt to it, and the experience yields less pleasure each time.

time and variety are two ways to avoid habituation, and if you have one, then you don’t need the other. In fact when episodes are sufficiently separated in time, variety is not only unnecessary–it can actually be costly.