This project idea comes to you from REACH in Montreal, Quebec.

This is a simple activity that you can try out on your friends. First, get them to sit down with their backs to you. Give them a piece of paper and a pencil and instruct them to make a tally mark every time you say "write". Then, strike a table or the floor with a wooden rod and simultaneously say "write" for a total of 20 times with 2-second intervals between the taps. Continue striking the desk, but stop saying "write" until your friends have stopped writing. Count the tally marks that they made, and only then tell your friends that you said "write" exactly 20 times.

What happened? Most of your friends probably made more than 20 tallies. That's because when the response-eliciting stimulus (like the saying of the word "write") was paired with the neutral stimulus (like taps with the wooden rod), your friends became conditioned to the neutral stimulus, so that the neutral stimulus elicited the response even when it was presented alone. The conditioning became extinguished after a certain time because the presentation of the conditioned stimulus (tapping noise) was continued without pairing with the unconditioned stimulus (the saying of the word "write").

This conditioning of the human being to neutral stimuli occurs in daily life. For example, when the preparation of a meal is constantly accompanied by the clatter of kitchen utensils, hearing only the clatter will stimulate the feeling of hunger and might even stimulate the production of saliva in the salivary glands (drooling).