Reinforcement = anything that increases the likelihood of a given behavior.

     Positive reinforcement:  CS + UCS - UCR =  CS - CR.  Translation:  a conditioned stimulus (bell) is presented simultaneously with an unconditioned stimulus (a fat, juicy steak) leading to an unconditioned response (salivation).  It's unconditioned because it doesn't need to be conditioned - it's a natural response.  After several trials, you can ring the bell (now a conditioned stimulus) and evoke salivation (now a conditioned response).  Positive reinforcement, as the term implies, reinforces behavior.  If you go to lecture and the lecturer is funny, you are more likely to attend next time (assuming you like to laugh). A monkey given cocaine every time he hits a lever will hit that lever until he is dead, foregoing all other pleasures and needs.  The most powerful reinforcement schedule is an intermittent reinforcement schedule (such as a slot machine)  that gives you a payoff only occasionally, but not every time.

    Negative reinforcement:  this is NOT punishment, but is frequently confused with it.  Negative reinforcement is really a variant of positive reinforcement, in that a behavior is associated not with something good, but the REMOVAL of something bad.  For example, if you take Prozac for 2 weeks and find that you are no longer depressed, this is a negative reinforcement schedule, since something negative (the depression) was removed.  You don't feel high or euphoric, but you no longer feel depressed.  If Prozac were to make you feel high or euphoric, then it would be a positive reinforcement schedule.  Negative reinforcement is somewhat akin to the idea expressed in the slogan, "The beatings will stop when morale improves."

    Punishment is just what it sounds like.  You spill your milk; your mother slaps your face (we didn't have time-outs in my day).   You're less likely to spill your milk again, which is the effect of punishment.  In learning theory, the term is used to refer to a noxious stimulus (slap) which leads to the reduction of a contingent behavior (spilling your milk).

    Exposure is also just what it sounds like:  you expose the salivating dog to the bell enough times without giving him the steak and pretty soon his salivary glands will catch on.  This failure to respond after repeated exposure to a conditioned stimulus without the unconditioned stimulus is known as extinction.   This is where the old adage about remounting the horse that threw you came from.  If the last time you drove a car, you got into an accident, you will probably be very nervous when you drive again.  However, assuming you don't get into an accident for several car trips, your anxiety will diminish, since the unconditioned stimulus (car accident) is no longer linked to the conditioned stimulus (getting in your car), so no longer leads to a conditioned response (anxiety, sweaty palms, racing heart).

    Reciprocal inhibition refers to doing something relaxing (such as meditating) while in an anxiety-provoking situation (such as on an airplane while experiencing severe turbulence).  Since relaxation is considered to be incompatible with anxiety, it inhibits it (reciprocally).  You might still crash, but your last few minutes of life will be calm and serene.

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