July 4th, 2009
Misusing the term “negative reinforcement” is a common error. Typically, when people use “negative reinforcement” they are trying to say something about making a behaviour less common: “Getting fined for filing your taxes late is some serious negative reinforcement!” But this is incorrect. Here are the relevant terms with definitions:
Positive reinforcement: strengthening a tendency to respond in a certain manner by presenting a pleasant event.
Example: Giving an ice cream cone to a child after they clean their room. (The behaviour reinforced is cleaning the room.)
Negative reinforcement: strengthening a tendency to respond in a certain manner by removing an aversive agent.
Example: A three year old shouts “Please can I have an ice cream please please please please please please (etc.)” over and over until the ice cream is given to them, at which point they stop shouting. (The behaviour reinforced is giving the child ice cream.)
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So the key is that in both cases, a certain behaviour is being reinforced, in other words rewarded with the goal of making it more common. This is the opposite of what most people mean when they say “negative reinforcement,” which is actually…
Punishment: A noxious or unpleasant stimulus imposed on someone in order to reduce the frequency of a particular behaviour.
Example: Shouting at a child after they drop their ice cream cone on the floor. (The behaviour being punished is making a mess.)
Oddly enough, I used those phrases in my post the other day because I get chided by my electrical engineering friends for misusing “positive feedback” and “negative feedback”. I’m not sure what to call the “meat is actually pretty gross, gosh how smart I am to avoid it” feeling and the “meat brings pain” feeling.
Crap, I don’t know how those extraneous characters were added to my name. Blech.
You are henceforth known as Laraack. Is that 2 or 3 syllables?
Hmmm. I would say “meat brings pain” is best classified as a punishment, since it is an aversive stimulus that makes you less likely to eat meat. And “I am smart to avoid pain” is from negative reinforcement, the cessation of bad feelings in your body after eating meat.
Pos. and neg. feedback might mean something different though. Does feedback have some technical engineering meaning or is it just “comments about your work”? If the latter I assume negative feedback is just criticism (punishment) and positive feedback is reward (positive reinforcement)?
Don’t be silly, it’s four.
From a mechanical or electrical engineering point of view, negative feedback works to inhibit the force that triggered it. For example, on an automated train system, you would set upper and lower limits for the speed. If the speed exceeds the upper limit, it would trigger negative feedback to slow it down. If it is less than the lower limit, it would trigger negative feedback to speed it up.
Positive feedback works to enhance the force that triggered it. In the above example, if it exceeded the upper limit of the speed, the positive feedback would work to speed the train up even more. Each subsequent check of the system would indicate that it was above the upper limit, and increase the speed. Which is why positive feedback loops are inherently unstable.
Whenever I use those phrases on my LJ, my smart ass engineering friends make geeky jokes about feedback loops. Which I tried to avoid.
Ahh. I think I see the difference – feedback vs. reinforcement. Reinforcement always makes the thing (behaviour or whatever) happen more, whether it’s positive or negative. Negatie feedback probably equates, metaphorically speaking, to punishment.
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