An Experiment On Sniffy The Virtual Rat

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Introduction

Sniffy is a virtual rat who is going to experience classical conditioning. Classical conditioning shows that learning can occur without reward or punishment based on the pairing of an unconditioned stimulus (US), a neutral stimulus (NS) unconditioned response (UR). Eventually after repeated pairing of the US, NS, and NR, the NS becomes a conditioned stimulus (CS) and the UR becomes conditioned response (CR) showing that the US and UR have been successfully paired and learning has occurred (Lefrancois 31). For example, in the case of Ivan Pavlov, he paired food (US) with a bell (CS), causing dogs to salivate every time they heard the bell (CR).

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The movement ratio allows one to tell whether Sniffy is learning and becoming conditioned, or if the conditioning is not working. This is also known as acquisition, when learning occurs because a classically conditioned response can be seen from repeated pairing between the CS and US (Alloway 32).The movement ratio measures the amount of time that Sniffy spends freezing (showing fear) to the US, if Sniffy does show freezing, it means that conditioning has taken place and that the US has become a CS, showing learning has also taken place (Alloway 22).

Freezing occurs because a conditioned emotional response has been created because of the CS. For example, Sniffy receives a tone (NS) and then a shock (US), which then leads to fear (UR). After repeated pairing with the shock, Sniffy freezes just from hearing the tone, showing that a conditioned emotional response has been attached to the tone.

After a period of time passes without presenting Sniffy with the NS and US, Sniffy can develop extinction to the stimuli. Extinction means that the CS no longer produces the CR of fear and Sniffy no longer freezes. If extinction occurs, it is also possible that spontaneous recovery can occur as well. Spontaneous recovery means that after multiple trials of Sniffy showing extinction, during one trial if he hears the tone, Sniffy freezes. Spontaneous recovery shows that Sniffy briefly remembered the tone being paired with the shock, causing him to show fear and freeze.

The researcher hypothesizes that Sniffy will associate the tone with shock after ten pairings, as indicated by Sniffy’s movement ratio (freezing). It is also hypothesized that if the tone is no longer paired with shock for thirty pairings, the response will be extinction, as indicated by Sniffy’s movement ration and lack of freezing. The researcher also hypothesizes that if Sniffy were removed from his chamber for twenty-four hours, then placed back in it and presented the tone again, without shock, he would likely continue to demonstrate extinction of fear, but could experience spontaneous recovery for a few trials. It is also hypothesized that Sniffy will learn to associate a high intensity light with a high intensity shock after thirty pairings. The researcher also hypothesizes that if Sniffy is presented with two neutral stimuli: a low intensity light and high intensity tone, with a medium intensity shock, his movement ratio will show multiple times of freezing. Lastly, the researcher hypothesizes that Sniffy will exhibit signs of higher order conditioning when a light (NS) is paired with a shock (US) and then a tone (NS) is paired with a light (US). The researcher believes Sniffy will exhibit freezing when hearing the tone after multiple pairings with the light.

Method

Subject: Sniffy is a virtual white lab rat that has never been trained before. He is in an isolation chamber and has had no previous learning to any of the stimuli. Sniffy constantly moves around the chamber, sniffing, he also stops occasionally and stands on his hind legs.

Materials: Sniffy’s isolation chamber contains a lever that a rat can be trained to press to dispense food, as well as the ability to present other stimuli (light, tone, bell, and shock) (Alloway 1). In experiment one, Sniffy is introduced to a medium intensity tone and a medium intensity shock. In experiment two, Sniffy is introduced to a medium intensity tone. In experiment three, a high intensity light and high intensity shock is used on Sniffy. A low intensity light, high intensity tone and a medium intensity shock are also used.

Procedure: In experiment one, Sniffy is introduced to a medium intensity tone (NS) and a medium intensity shock (US), for ten trials. There is a five minute interval between trials. In experiment two, Sniffy is introduced to a medium intensity tone (NS) thirty times, without the medium intensity shock in order to test whether extinction has occurred since experiment one. There is a five minute interval between trials Experiment three part one, Sniffy is removed from the isolation chamber for twenty-four hours. Sniffy is then introduced to a medium intensity tone for fifteen trials in order to test if spontaneous recovery has occurred. There is a five minute interval between each trial. In experiment three part one, sniffy is introduced to a high intensity light, with a medium intensity shock for thirty trials. There is a three minute interval between trials. In experiment three part three, sniffy is removed for another twenty-four hour timeout. He is then introduced to a low intensity light, high intensity tone, and high intensity shock for thirty pairings with three minute intervals.

In experiment four, a new Sniffy is used to attempt higher order conditioning. In stage one, Sniffy is exposed to a medium intensity tone paired with a medium intensity shock for thirty trials with intervals of three minutes. In stage two, nothing is changed and again Sniffy is exposed to a medium intensity tone paired with a medium intensity shock for thirty trials with intervals of three minutes. In stage three, Sniffy is exposed to a medium intensity light paired with a medium intensity tone and no shock for thirty trials in intervals of three minutes. Lastly, in stage four, Sniffy is exposed to only a medium intensity light for thirty trials in intervals of three minutes in order to test if freezing will occur and if higher order conditioning had taken place. The goal was to pair the light with the tone, which had already been paired with the shock, in order to elicit fear in Sniffy to the shock from the light without ever pairing the light and the shock.

Results

Sniffy Experiment 1

Movement Ratio Graph

CS Response Strength Graph

The numbers along x-axis show what experiment Sniffy is on. The y-axis on the movement ratio graph shows the amount of freezing Sniffy did on each trial. The y-axis on the CS Response Strength Graph shows the amount of response Sniffy had to each CS. Both graphs demonstrate that when paired with a medium intensity shock, a medium intensity tone elicits a positive relationship in Sniffy and results in multiple instances of freezing.

Sniffy Experiment 2

Movement Ratio Graph

CS Response Strength Graph

The numbers along x-axis show what experiment Sniffy is on. The y-axis on the movement ratio graph shows the amount of freezing Sniffy did on each trial. The y-axis on the CS Response Strength Graph shows the amount of response Sniffy had to each CS. Both graphs demonstrate that initially the medium intensity tone elicited fear and a strong relationship, but started to decrease as it was no longer paired with shock.

Sniffy Experiment 3 Part 1

Movement Ratio Graph

CS Response Strength Graph

The numbers along x-axis show what experiment Sniffy is on. The y-axis on the movement ratio graph shows the amount of freezing Sniffy did on each trial. The y-axis on the CS Response Strength Graph shows the amount of response Sniffy had to each CS. The graphs from this experiment show that although Sniffy was removed from the chamber for twenty-four hours, spontaneous recovery did occur and Sniffy still showed fear from the medium intensity tone.

Sniffy Experiment 3 Part 2

Movement Ratio Graph

CS Response Strength Graph

The numbers along x-axis show what experiment Sniffy is on. The y-axis on the movement ratio graph shows the amount of freezing Sniffy did on each trial. The y-axis on the CS Response Strength Graph shows the amount of response Sniffy had to each CS. The graphs for this experiment show that when presented with a medium intensity light, high intensity tone, and high intensity shock, Sniffy demonstrated a positive relationship and many strong instances of freezing.

Sniffy Experiment 3 Part 3

Movement Ratio Graph

CS Response Strength Graph

Sniffy Experiment 4

Movement Ratio Graph

CS Response Strength Graph

The numbers along x-axis show what experiment Sniffy is on. The y-axis on the movement ratio graph shows the amount of freezing Sniffy did on each trial. The y-axis on the CS Response Strength Graph shows the amount of response Sniffy had to each CS. Although initially Sniffy was showing a strong CS relationship and instances of freezing from the pairing of the tone and shock. However, the researcher was unable to create a higher order conditioning within Sniffy and create a strong relationship and freezing among the pairing of the light and tone, as well as just the light itself. Sniffy only showed a relationship when the tone was present.