Extinction of a Conditioned Stimulus
Method:
In this experiment, an untrained rat was utilized in order to display the Movement Ratio. 1 stage was selected with ten (10) trials. Each trial had a five (5) minute interval between trials to allow the rat to recover from the medium intensity shock. A medium intensity tone was selected as the Conditioned Stimulus (CS) selected to precede the Unconditioned Stimulus (US), a medium intensity shock.
Stage 2 was selected with thirty (30) trials. Each had a five (5) minute interval between trials to allow the rat to recover from the medium intensity shock. A medium intensity tone was selected as the Conditioned Stimulus (CS) to precede the new Unconditioned Stimulus (US), no stimulus.
Hypothesis:
In the first set of trials, Sniffy will learn to associate the tone with shock; illustrating fear-related behavior or freezing behavior at the tone. In the second set of trials, stage 2, elimination of a conditioned response (CR) (freezing or fear-related behavior) learned in the first set of trials will occur by repeatedly presenting the CS without the US.
Results:
In the first set of trials; the increase from 0 to 0.7 in the Movement Ratio illustrates that the tone CS, is acquiring the capacity to induce freezing behavior and other fear-related behaviors. As the movement ratio increases, the CS response strength mind window show that the tone’s capacity to elicit fear as a psychological process is increasing.
In the second set of trials; the movement ratio window illustrates that repeatedly presenting the CS without the US causes the CS to gradually stop eliciting the freezing and other fear-related behavior. The CS Response Strength mind window shows that this behaviors change is the result of the CS’s losing its capacity to elicit the fear response.
Independent Variable (IV) – first trial = shock; second trail = none
Dependent variable (DV) – first and second; fear-related behavior, freezing