Types of Reinforcers
Learning Activities (Click on hyperlinks for activity worksheets.) 1. Definitions 2. Identify concepts from animal acts (Refer to the Clucking Calculator and the Drumming Duck.) 3. Provide your own examples 4. Crossword puzzle 5. Word search
Click on the thumbnails below to enlarge.	Positive Reinforcer
	Most of the training at the IQ Zoo and at ABE involved the use of positive reinforcers, delivered during the process of positive reinforcement. Positive reinforcement is the reinforcing of an organism for exhibiting a particular behavior. The positive reinforcer is the stimulus (reward) that is introduced into the organism's environment after the behavior is exhibited. It is said to "increase the probability of the behavior" or "increase the rate of behavior" or "strengthen the behavior." In short, the animal is more likely to do the behavior if the behavior is reinforced. The most common positive reinforcer used by ABE was food. In the photo to the left, we see a dolphin trainer with her right hand in the fish bucket. After the dolphin touches its nose to the target, the trainer will immediately reinforce nose-touching with food (a delicious frozen fish). The fish is the positive reinforcer, and it should be delivered by the trainer immediately after the dolphin exhibits the desired behavior. In the other photo, we see a trainer presenting food (grain) to a chicken after the chicken has walked through the tunnel. The grain is the positive reinforcer. (You might also notice that the grain cup has a blue/white clicker on it. Because the sound of the clicker is repeatedly sounded before the delivery of food, the clicker itself will also become a positive reinforcer.)
	Negative Reinforcers and Punishers
	Most of the training by ABE involved the use of positive stimuli. However aversive stimuli or negative reinforcers may be used to modify behavior. Negative reinforcement increases the rate of behavior, whereas punishment decreases the rate of behavior. Negative reinforcement occurs when a behavior is reinforced by allowing the animal to remove or avoid something unpleasant in its environment. Once again, negative reinforcement increases the probability of the behavior. The negative reinforcer is the aversive stimulus that is removed or avoided after the behavior is exhibited. Thus, the negative reinforcer is usually a stimulus that we would refer to as aversive or unpleasant to the animal. Careful - a process that is sometimes confused with negative reinforcement is punishment, in which an aversive stimulus is presented after a behavior occurs. Punishment decreases the probability of a behavior. Once again, ABE seldom if ever used aversive stimuli in its work, in the form of negative reinforcement or punishment, although ABE did use extinction, which is sometimes classified as a form of punishment because it too decreases the probability of a behavior. Because ABE was so successful in its accomplishments, its reliance on positive reinforcement and not on punishment or negative reinforcement should be a lesson to us all!
Click on the thumbnail below to enlarge.	Primary Reinforcer
	A primary reinforcer is a reinforcer that is not learned; it is "naturally" reinforcing. The most common primary reinforcer used by ABE was food. Other stimuli that could be used as positive reinforcers for many animals would include water, warmth, and access to a mate. Food used as positive reinforcers should be appropriate to the animal - fish for dolphins, meat for dogs, and grain for chickens. In the photo, Keller Breland is reinforcing the dog with meat from a cup. The meat is naturally reinforcing to dogs, so it is a primary reinforcer.
Click on the thumbnails below to enlarge.	Secondary (Conditioned) Reinforcer
	A secondary reinforcer or conditioned reinforcer is learned; it is not a stimulus that is naturally reinforcing. The most common secondary reinforcer used by ABE was a sound that was associated with the delivery of food. As a result of pairing the sound with a primary reinforcer (food), the sound becomes a reinforcer by itself (a secondary reinforcer). Terms that are basically synonymous with secondary reinforcer include conditioned reinforcer and bridge. In this picture, Keller Breland has a whistle in his mouth. After the dog performs the required behavior, Keller would blow the whistle and then immediately present the meat to the dog. Through this pairing, the whistle itself would become a reinforcer. In the same way, the clicker on the food cup is pressed immediately before the food cup is presented to the chicken. If the clicker is presented right before the food is presented, the clicker will function as a secondary reinforcer. Many of the animal acts developed by ABE consisted of animals in displays that functioned as fancy Skinner boxes. When food was delivered in the box, the delivery mechanism made a unique sound (e.g., a "clunk" that occurred every time the feeder operated). This sound would become a secondary reinforcer. A benefit to the clunking sound, whistle, or clicker is this - these sounds could be presented immediately to the animal after the animal performed the behavior. This immediacy of reinforcement makes behavior training and the performance of behavior much more effective (see "bridge").
	Conditioned Reinforcer
	A conditioned reinforcer is, for the most part, another name for a secondary reinforcer (see “secondary reinforcer” above).  (See also "bridge.")
Click on the thumbnail below to enlarge.	Bridge
	In his work, Keller Breland introduced the term "bridge" in the place of "secondary reinforcer" or "conditioned reinforcer." (The term bridge is not a technical term in widespread use by experimental psychologists, but the term is used a lot by animal trainers because it makes sense to the lay person.) Early in their careers and under the influence of B. F. Skinner, the Brelands realized that the immediate delivery of a reinforcer was crucial if (a) the animal was going to learn something quickly and (2) if the trainer was going to have any significant impact on controlling the behavior of the animal. For example, they realized that, in training chickens, a sound like a "click" needed to follow the desired behavior immediately after the behavior occurred (even a delay of a second or two could mar performance). Unfortunately, it takes a while for the trainer to deliver the food (e.g., it would take a few seconds for the trainer to move the cup from behind his or her back, where it might have to be kept out of reach, into position in front of the dog or chicken). But a clicker could deliver a reinforcer (a "click") very quickly. In the same way, imagine working with a dolphin that is swimming in the middle of a pool, and imagine that you are reinforcing the dolphin's touching, with its nose, a ball floating on the surface of the pool. How can you reinforce the dolphin when it is so far away? The Brelands realized early in their careers that you could use something like a whistle to deliver an immediate reinforcer. Because the whistle acted as a "bridge" from the time the animal performed the behavior until the time that the food (or primary reinforcer) was delivered, Keller called this type of stimulus a "bridge" or a "bridging stimulus."