The exhibit is a serious of columns, which you pass from right to left. The penultimate column is to illustrate the idea of ice, and you’re invited by a palm shape to put your palm to the column (which is indeed cold). The interesting thing is the final column, which is meant to illustrate gravity somehow (it was broken yesterday, so I don’t know how it is supposed to do this). Notice how the metal around the IVY of gravity is worn away. None of the other columns had this. Obviously hundreds of visitors a day are drawn to this exhibit, press their palms to the ICE column and then go on to touch, in exactly the same way, the GRAVITY column even though this isn’t part of the way they are supposed to interact with the exhibit.
Psychologists know that what people have done before is the best predictor of what they will do in the future. Whole industries are devoted to helping us establish, or break, habits. This exhibit on geological forces illustrates how easily some behavioural precedents can be set. We love touching things, and although we aren’t meant to, permission to do it once is all that is required to set off an immediate repetition of the behaviour.