Glossary of Animal Training Terminology

Approximation - One small step, in a series of progressive steps that lead to the behavioral goal.

Aversive Stimulus - A stimulus whose termination or removal causes an increase in the frequency of behavior.

Avoidance Behavior - A behavior that increases in frequency because it postpones the delivery of an aversive stimulus (and is therefore negatively reinforced).

Balance of Reinforcement - The relationship between the reinforcing value of an action, whether positive or negative, with the percentage of positive vs. negative reinforcement given following a specific act. For example, the balance of reinforcement would positive if the behavior is followed by a positive consequence a high percentage of the time.

Behavioral Criterion - The level or behavioral response that must be met to earn reinforcement.

Behavioral Drift- Situation in which a previously trained behavior changes slightly over time, often due to slight inconsistencies in the trainers' cues, criteria, and reinforcement schedules.

Bridging Stimulus - A stimulus that can act as both an SD and a secondary reinforcer. It pinpoints the exact moment of reinforcement in a desired behavior. The "bridge" (often a clicker, whistle or word) communicates to the subject that it has performed correctly and signals that reinforcement is forthcoming. It "bridges" the gap between the time the correct response is given and the time the reinforcer is delivered.

Capture (Scan) - To place a naturally occurring behavior (or Unconditioned Response) under stimulus control by reinforcing the behavior as it occurs.

Chain Behavior - An individual response linking two or more individual behaviors in a specific order, elicited by a common discriminative stimulus (SD), or other stimulus. Each response acts as a conditioned reinforcer for the previous response and also provides the stimulus for the next behavior in the chain. The behavior is typically bridged at the end of the chain; the bridge serves as a conditioned reinforcer for the entire chain.

Classical Conditioning (Pavlovian or Respondent Conditioning) - A basic form of learning in which stimuli initially incapable of evoking a reflex response acquire the ability to do so through repeated pairing with other stimuli that are able to elicit that response; a method of behavior modification where the presentation of an unconditioned stimulus (US) causes an unconditioned response (UR), which is emitted reflexively. This type of conditioning does not involve any voluntary choices by the animal; the response or reaction is reflexive.

Conditioned Response (CR) - A type of learned response that occurs following the presentation of a specific stimulus.

Conditioned Stimulus (CS) - A signal that will elicit a specific response as a result of a learned association between that stimulus and that response.

Conditioning - A form of learning in which a change in behavior is due to changes or influences in the environment; the operation of associating an act or object with a stimulus to modify or mold behaviors.

Continuous Reinforcement - A schedule of reinforcement in which each correct response is followed by a positive reinforcer.

Desensitization - The lessening or disappearance of a (often negative) response through the pairing of a positive reinforcer with the negative stimulus or event; the process of turning an unfamiliar object or even (usually negative) toward a neutral position. The object or event can then be paired with positive reinforcers to make it positive.

Differential Reinforcement (Selective Reinforcement) - The act of selectively reinforcing desirable responses to shape the topography of a specific behavior.

Differential Reinforcement of an Incompatible Behavior (DRI) - Schedule of reinforcement used to cause a decrease in the frequency of an undesirable behavior, in which the subject is reinforced for performing a behavior that competes, or is incompatible with, the undesirable behavior.

Differential Reinforcement of Other Behavior (DRO) - Schedule of reinforcement used to cause a decrease in the frequency of an undesirable behavior, in which the subject is reinforced for emitting any response other than the undesirable behavior.

Discrimination - The ability, acquired through learning, to make distinctions between stimuli that are similar but not exactly alike.

Discriminative Stimulus (SD, Cue, Signal) - A stimulus that precedes a behavior, signaling that a specific response will be reinforced if emitted correctly. The result is that the stimulus will consistently elicit that particular response.

Extinction - Process in which reinforcement is no longer delivered following a specific, previously reinforced behavior. Eventually the behavior dies out due to lack of reinforcement.

Extinction Burst - The increase in a response that is brought on by the withdrawal of reinforcement. Extinction burst occurs just prior to the decline of behavior (due to lack of reinforcement) prior to extinction.

Fixed Interval Schedule of Reinforcement - A schedule of reinforcement in which reinforcement follows the first correct response after a set amount of time has elapsed since previous reinforcement. For example, if an animal is reinforced every 5 seconds (assuming the last response is correct), this is expressed as FI=5 seconds.

Fixed Ratio Schedule of Reinforcement - A schedule of reinforcement in which reinforcement follows the correct response after a set number of responses. For example, if every second response is reinforced, FR=2.

Generalization - The lack of discrimination between two stimuli. An animal that has been conditioned to respond to a specific stimulus may offer the same response in the presence of a similar stimulus.

Incompatible Behavior - A behavior that is impossible to perform at the same time as another specific behavior. For example, running and sitting are incompatible behaviors as one subject cannot perform both simultaneously.

Jackpot (Bonus) - A positive reinforcer that is much larger than usual, and usually unexpected.

Latency - The interval of time between the stimulus and response.

Least Reinforcing Stimulus - All interaction or reinforcement, positive or negative, is withheld for a period of time (generally a few seconds) so as not to reinforce an undesirable behavior or lack of response. Also termed Least Reinforcing Scenario, serving as a stimulus for calm behavior following an incorrect response, which helps to reduce frustration that might result from a lack of reinforcement.

Magnitude of Reinforcement - Refers to the size, strength, and duration of the reinforcement following a behavior.

Negative Reinforcement - An act that increases the frequency of a behavior by providing an aversive stimulus that the subject will work to avoid or escape. The frequency of behavior increases to avoid the onset of or to terminate the aversive stimulus.

Observational Learning - A type of learning in which the behavior of another organism is observed and imitated.

Operant Conditioning - A type of learning in which behavior is determined by its consequences. A positive consequence to a behavior will increase the likelihood of the behavior being repeated, while an undesirable consequence will decrease the likelihood of the behavior being repeated.

Positive Reinforcement - The addition of a desirable stimulus to the subject's environment following a behavior, thereby causing an increase in the frequency occurrence of that behavior.

Primary Reinforcer (Unconditioned Reinforcer) - A reinforcing event that does not depend on learning or previous experience to achieve its reinforcing properties (e.g. biological need: food, water, sex).

Punishment - An act that occurs immediately after an undesirable behavior it is meant to affect, and causes a decrease in the frequency of that behavior. This can be in the form of the administration of an aversive stimulus or event (positive punishment) or the removal of a desirable stimulus (negative punishment); Anything that decrease the frequency of the behavior it immediately follows.

Regression - The state of a previously conditioned behavior reverting back to a lower stage of development.

Reinforcer - An object, action or other stimulus that causes an increase in the frequency of a response.

Schedule of Reinforcement - The conditions under which reinforcement is delivered.

Secondary Reinforcer (Conditioned Reinforcer) - An object or event that initially may mean nothing to the animal but becomes reinforcing through pairing with a primary reinforcer.

Shaping - An operant conditioning method of taking an action or tendency and shifting it, one approximation at a time (successive approximations), toward the final behavioral goal.

Stimulus Control - Once a behavior is shaped, it is said to be under stimulus control if it meets 3 conditions: 1) It is immediately offered following the SD; 2) It is offered only when preceded by the correct SD; and 3) It is not offered in the presence of another SD.

Superstitious Behavior - A behavior that is unrelated to the behavior being conditioned but has inadvertently been reinforced often enough that it becomes fixed in the subject's mind as necessary in order to receive reinforcement.

Target (noun) - A prop (or position) which pinpoints a specific location for an animal to touch, approach, or follow, e.g. a trainer teaches a rhino to touch its lip to the end of a stick. Using this technique to shape a behavior is called "targeting."

Target (verb) - The act of an animal touching a predetermined target, (spot, point or prop) with a designated body part.

Time-out - Type of mild punishment (negative punishment) in which the trainer ceases to provide stimuli or responses (i.e. removes him/herself and all other opportunity for reinforcement from the training situation) for a period of time with the intent of causing a decrease in the frequency or occurrence of an undesired response.

Unconditioned Stimulus (US) - In Classical Conditioning, any stimulus that can elicit reactions from a subject with out prior conditioning.

Variable Reinforcement - A reinforcement schedule in which the timing and/or delivery of the reinforcer is unpredictable.

Variable Interval Schedule of Reinforcement - A reinforcement schedule in which the reinforcement follows the first correct response after a varying amount of time. For example, if an animal is reinforced on the average of every 4 seconds, we say that VI=4.

Variable Ratio Schedule of Reinforcement - A reinforcement schedule in which reinforcement follows the first correct response after a varying number of responses. This is usually based on an average number of responses to be reinforced. For example, if the average is to be every third response (VR=3), the number of behaviors requested would average 3 between each reinforcement.