Basic Terms and Definitions Independent and Dependent Variables

Basic Terms and Definitions • Independent and Dependent Variables

• A variable is a characteristic of a person, place, or thing that can change (vary) over time or from one situation to another. • Temperature is an example of a variable; temperature varies from day to day, season to season, and place to place. • Height and weight are also examples of variables— people come in many different sizes and shapes.

• The independent variable is the aspect of an experiment that systematically varies across the different conditions in the experiment. • In other words, the independent variable is what is manipulated in an experiment

• For example, we may be interested in whether the size of a reward (or “reinforcer”) can affect the efficiency of learning. • we might conduct a maze learning experiment with rats. • Depending on the “experimental condition” to which the rat has been randomly assigned, it receives one, two, or three pellets of food each time it reaches the goal box. • Thus, the independent variable in this experiment is the number of food pellets the rats in each group receive when they reach the goal box.

• The dependent variable is the aspect of an experiment that is allowed to vary freely to see if it is affected by changes in the independent variable. • In other words, the dependent variable is what is measured in an experiment.

• In a psychology experiment, this is always some type of behavior.

• Changes in the dependent variable are dependent upon changes in the independent variable

• In behavioral research, the dependent variable is almost always some behavior, and the independent variable is some environmental event that is presumed to infl uence the behavior.

Stimulus and Response • A stimulus is any event that can potentially influence behavior, • response is a particular instance of a behavior. • For example, food is a stimulus that elicits the response of salivation when presented to a hungry dog.

• Similarly, loud music (a stimulus) might cause your neighbor to bang on the wall (a response), and a high mark on a test (a stimulus) might cause you to grin with delight (a response). The plural for the word stimulus is stimuli. Note that the response of one organism can act as a stimulus that influences the response of another organism. a smile from Shane is a stimulus that encourages Navi to say hello; Navi’s hello is in turn a stimulus that encourages Shane to introduce himself.

Overt and Covert Behavior • Overt behavior is behavior that has the potential for being directly observed by an individual other than the one performing the behavior. it is behavior that could be publicly observed if others were present. • A person’s response of saying hello and a rat’s response of pressing a lever are both instances of overt behavior.

• covert behavior is behavior that can be perceived only by the person performing the behavior. • In other words, it is behavior that is subjectively perceived and is not publicly observable. • Dreaming, thinking about your next chess move, visualizing how your date will go on the weekend, and feeling anxiety are all examples of covert behavior.

• Of course, some covert behaviors have components that could be made publicly observable • A feeling of anxiety, for example, is likely to involve increases in heart rate and muscle tension, both of which could be electronically measured.

Appetitive and Aversive Stimuli • An appetitive stimulus is an event that an organism will seek out. • Food is an appetitive stimulus when we are hungry; water is an appetitive stimulus when we are thirsty. • An aversive stimulus is an event that an organism will avoid. • Electric shock and extreme heat are examples of aversive stimuli.

Deprivation and Satiation • Deprivation is the prolonged absence of an event that tends to increase the appetitiveness of that event. Going without food for a long period of time obviously increases the appetitiveness of food, thereby increasing its ability to serve as a reinforcer for some behavior • Likewise, lack of social contact for several days (i. e. , social deprivation) will usually result in a strong desire for social contact.

• satiation refers to the prolonged exposure to (or consumption of ) an event, which tends to decrease the appetitiveness of that event. • Food is much less effective as a reinforcer for lever pressing if a rat has just eaten a large meal and is thus “satiated” on food. • Similarly, if you hear a favorite piece of music too often, you may grow tired of hearing it. • In fact, you might even become “sick of it” and avoid it, meaning the song has become aversive.

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Measurement of Behavior • Behavioral Definitions • behavioral definitions should be objective in the sense that they refer to some observable aspect of the individual’s behavior. • Therefore, defining aggression in terms of the physical characteristics of yelling and striking is more precise than defi ning it as feelings of anger.

• Behavioral defi nitions should also be clearly defi ned, that is, unambiguous. • For example, we might define yelling as a loud vocalization that continues for more than 5 seconds and can be heard outside a closed door. • Striking ? ?

• Striking might be defined as a rapid arm or leg movement that results in physical contact. • Our measurements of the behavior are relatively consistent over time and across settings. • what counts as an aggressive incident today will also count as an aggressive incident tomorrow.

• Finally, an unambiguous behavioral definition will make it easier for other researchers to replicate our results.

Recording Methods • Depending on how we define a behavior, there are several ways in which we can go about measuring it.

Rate of Response • is the frequency with which a response occurs in a certain period of time. • Rate measurements are most appropriate when the response is of brief duration, with a welldefined start and finish • The number of cigarettes smoked per day, the number of words written in a 1 -hour writing session,

• Certain experimental procedures have been explicitly designed to facilitate measuring behavior in terms of rate. • For example, operant conditioning experiments often involve rats pressing levers to earn food. The lever press is a very definable response because once the lever is pressed sufficiently for the microswitch to be activated, a response is electronically recorded.

Intensity • Responding can also be measured in terms of intensity. The intensity of a behavior is the force or magnitude of the behavior. • For example, in Pavlov’s classical conditioning procedure

• The strength of conditioning was typically measured as the amount (magnitude) of saliva produced whenever the tone was sounded by itself. • More saliva indicated stronger conditioning. • Likewise, it is intensity that we are concerned with when we teach a child to speak softly and to print firmly.

Duration • Duration is the length of time that an individual repeatedly or continuously performs a certain behavior. • This measure is appropriate when we are concerned with either increasing or decreasing the length of time the behavior occurs. • For example, a student may attempt to increase the amount of time he spends studying each week, as well as decrease the amount of time spent watching television.

Speed • Thus, speed is a measure of how quickly or slowly a behavior occurs, or the rapidity with which one progresses through some type of distance. • The length of time it takes for a rat to run through a maze from the start box to the goal box is a measure of speed.

Latency • The latency of a behavior is the length of time required for the behavior to begin. • With respect to classical conditioning of salivation, the strength of conditioning can be measured not in terms of the amount of saliva, but in terms of how soon the dog begins salivating after it hears the tone.

Number of Errors • Any behavior in which responses can be categorized as right or wrong can be assessed in terms of the number of errors. • For example, the number of wrong turns a rat takes before it finds its way through a maze to the goal box is one measure of how well the rat has learned the maze. • Likewise, the number of errors a student makes on an • exam is a standard method for determining how well the student knows the material.