The Effect of Trial Type on Freezing Behavior in Virtual Rats PDF

Preview

Summary

in class assignment required ...

Description

THE EFFECT OF TRIAL TYPE

1

The Effect of Trial Type on Freezing Behavior in Virtual Rats Fo0101 Wayne State University

Author Note Fo0101, Department of Psychology, Wayne State University This paper was written as part of the writing intensive requirements that are part of the experimental lab course. Correspondence regarding this paper should be addressed to fo0101, Department of Psychology, Wayne State University, Detroit, MI, 48202. Email: [email protected].

THE EFFECT OF TRIAL TYPE

2 Abstract

This experiment investigated the classical conditioning theory of learning on 208 virtual rats. Their response was measured by pairing the light stimulus (NS) with a shock (UCS) for observation. After performing the experiment, the results showed evidence of acquisition, extinction, and spontaneous recovery. Based off the results, they help support the theory of classical conditioning under investigation.

THE EFFECT OF TRIAL TYPE

3

The Effect of Trial Type on Freezing Behavior in Virtual Rats Classical Conditioning is a special type of conditioning in which a conditioned stimulus is paired up with a previously neutral stimulus until only the conditioned stimulus is able to create the response observed. To put it in a simpler manner: a learning through association is formed between the person and environment, eliciting a learned response after the presentation of a stimulus (Cherry, 2017). It is essential to go over some important terms of classical conditioning and see how the sequence and timing of the events are displayed in this process. According to McLeod (2014), there are three stages of classical conditioning: before, during, and after conditioning. In each stage, there are special terms for the stimuli and responses given to help give a clear understanding behind the process. In stage 1, the unconditioned stimulus (UCS) elicits an unconditioned response (UCR). The unconditioned stimulus is seen as a stimulus that naturally triggers a response, while the unconditioned response is seen as the unlearned response that naturally occurs from the unconditioned stimulus. For example, the smell of food may cause someone to feel very hungry (Goldman, 2012). Here, the smell of food is the unconditioned stimulus, while the feeling of hunger is the unconditioned response. During stage 2 of the classical conditioning process, a stimulus which doesn’t produce any response (Neutral Stimulus) is associated with the UCS to now become the conditioned stimulus (CS). The conditioned stimulus is seen as the “previously neutral stimulus that, after becoming associated with the unconditioned stimulus, eventually comes to trigger a conditioned response” (Cherry, 2017). For example, when a person gets an upset stomach (UCS), that might get associated with a certain type of food ingested, like sushi (CS). Lastly, during stage 3 of the classical conditioning process, after the association between the UCS and CS has been established, the CS can now elicit a response without any help from

THE EFFECT OF TRIAL TYPE

4

the UCS. This response from the CS is known as the conditioned response, which is the learned response from the previous neutral stimulus. An example of the conditioned response can be seen from Pavlov’s dog experiment. An association was formed between the bell (CS) and meat (UCS), causing the dog to drool (UCR). Now, the dog will begin to drool (CR) just from the bell itself (CS). Along with the main terms of learning by association, there are also three main principles involved in the process of classical conditioning as well: acquisition, extinction, and spontaneous recovery (Cherry, 2017). Acquisition occurs during the first stages of learning after having established a response. As mentioned earlier, a neural stimulus gets paired with an unconditioned stimulus causing an association between the two to be made. From this association, a response will now occur from the previous neural stimulus, now known as the conditioned stimulus and the response is acquired. Going back to Pavlov’s experiment, the response is acquired after the dog begins to salivate from the bell itself. Extinction occurs when the conditioned stimulus is presented alone without the unconditioned stimulus, causing the conditioned response to eventually cease or disappear. Lastly, spontaneous recovery occurs when, after a period of rest, the conditioned response reappears again in response to the presentation of the conditioned stimulus. Both extinction and spontaneous recovery can be seen from the dog salivation experiment. After having trained the dog to salivate from the bell alone, there comes a period of no reinforcement of the behavior and because of that, the dog’s response will eventually go away (extinction). However, after a certain amount of rest period where the CS didn’t occur, the ringing of the bell suddenly causes the dog to recover the learned response of salivating again (spontaneous recovery). There is a lot of research that investigated classical conditioning, with one study done by Ratner and Miller.

THE EFFECT OF TRIAL TYPE

5

Ratner and Miller (1959) conducted a study to examine classical conditioning on earthworms. A total of 32 earthworms were used in this study for investigation. There were a total of 4 groups used in the study: Experimental group (E), vibration control group (V), randomresponse control group (R), and light control group (L). In the E group, only the light (US) and vibratory stimulus (CS) were presented. In the V group, only the CS was presented. In the R group, neither vibration nor light was presented. Lastly, in the L group, only the US was presented. The light represents the US, retraction behavior is the UCR, vibration represents both the NS and CS, and retraction is the CR. For the E group, a total of 100 conditioning trials were conducted with the CS presented first for 6 seconds, and the US presented for 2 seconds where both stimuli would overlap. When the CS was presented alone, it would elicit a CR as well. As mentioned earlier, the procedure for the other three groups was different compared to the E group. The V group was presented with the CS only, with the US absent. The R group was presented with neither stimulus, while the L group was presented with just the light. The results for this study show a sharp increase for the E group displaying more conditioned responses than the other three groups. In addition, there was also a decrease in displaying conditioned responses during the extinction trials as well. Compared to the E group, the other three groups showed no clear pattern in terms of their behavior throughout the conditioning trials in the study (Ratner & Miller, 1959). The results given from this study provide evidence of both conditioning and extinction in earthworms. Evidence for conditioning can be seen with the increase in percentage of conditioned responses in the conditioning trials. This shows that acquisition took place and a response was established. Furthermore, this result shows that learning through association did occur between the vibration stimulus (CS) and retraction (CR). Evidence for extinction can be seen with the decrease in percentage of conditioned responses after the conditioning trials. The

THE EFFECT OF TRIAL TYPE

6

decrease in behavior can be attributed due to the UCS being removed, causing a gradual weakening of the CR. Because of the weakened CR, the behavior would decrease or disappear over time. Another study that looked into classical conditioning was from Kellogg and Spanovick (1953) who examined classical conditioning on fish. A total of 24 striped mullets were used in this study for investigation. There were 2 conditioning groups used in this study: the Bell (B) and Light (L) group, with each having 8 fish total. The B group was only presented with the bell, while the L group was only presented with the light. The electric shock represented the UCS, fin extension was the UCR, the light and bell was the NS and CS, and fin extension represented the CR. For the conditioning procedure, the CS lasted for only 3 seconds, while the UCS overlapped with the conditioned during the last second of the 3-second interval. The study adapted to using just 70 training trials in order to help get the CR. It was found that 10 successive fin movement responses (CR) could be achieved within 70 trials or less. The results of the study show a gradual increase in the percent frequency of the CR’s for both experimental groups, providing evidence of conditioning during the trials. Furthermore, the results show that the L group conditioned faster than the B group, which were occurring at different rates during the conditioning trials (Kellogg & Spanovick, 1953). As mentioned earlier, the results given from this study provide evidence of conditioning in the fish. Evidence for conditioning can be seen with the increase in percentage frequency of conditioned responses in the conditioning trials. This shows that acquisition took place and a response was established. Furthermore, this result shows that learning through association did occur between the light and bell (CS) and fin movement (CR). One last study that investigated classical conditioning was one performed by Smith and Miller.

THE EFFECT OF TRIAL TYPE

7

Smith and Miller (1960) conducted a study to examine classical conditioning on horseshoe crabs. A total of 18 horseshoe crabs were used in this study for investigation. There were a total of 3 groups used in the study: Experimental group (E), light-control group (L-C), and the shock-control group (S-C). In the E group, only the shock (US) and light (CS) were presented. In the L-C group, only the CS was presented. In the S-C group, only the US was presented. The shock represents the US, tail movement is the UCR, light represents both the NS and CS, and tail movement is the CR. For the E group, after 5 minutes of adaptation, the subjects went through 20 conditioning trials with a 10 second light stimulus with a 1 second shock overlapping with the last second of the light. As mentioned earlier, the procedure for the other 2 groups was different compared to the E group. The L-C group was presented with the CS only, with the US absent. The S-C group was presented with just the shock. The results for this study show a gradual increase for the E group displaying more conditioned responses compared to the other two groups. In addition, there was also a decrease in displaying conditioned responses during the extinction trials too. Compared to the E group, the other two control groups showed no clear pattern in terms of tail movement throughout the conditioning trials in the study (Smith & Miller, 1960). The results given from this study help provide evidence of both conditioning and extinction in horseshoe crabs. Evidence for conditioning can be seen with the increase in the number of conditioned responses in the conditioning trials. This shows that acquisition took place and that a learning through association occurred between the light (CS) and tail movement (CR). Evidence for extinction can be seen with the decrease in number of conditioned responses after the conditioning trials. This decrease in behavior can be attributed to the shock (UCS) being removed, causing the subjects to show a weakened CR. Because of the weakened CR, the behavior of tail movement would decrease or disappear over time. All of the studies discussed

THE EFFECT OF TRIAL TYPE

8

help to show evidence of classical conditioning. With these findings, they can be applied toward the Sniffy virtual rat experiment done in class. This study examined the classical conditioning theory of learning by looking at three aspects of the learning process: acquisition, extinction, and spontaneous recovery. The main question that this study was looking into was how would Sniffy respond, in terms of freezing behavior, to the three phases of classical conditioning? It is important to answer this question because it highlights the importance of learning behavior from the interaction between a person and the environment. The experiment was conducted using a virtual rat with light (NS) and shock (UCS). In the acquisition phase, light and shock were presented to the rat. Then in the extinction phase, only light was presented. Lastly, in the spontaneous recovery phase, only light was presented again to the rat. Beginning with the Pre-acquisition trial to the Post-acquisition trial, it was expected that Sniffy would freeze more over time. From the Post-acquisition trial to the Extinction trial, it was expected that there would be no significant difference, as Sniffy would remain the same in time of freezing. Then during the Extinction trial, Sniffy was expected to freeze less during the end of the Extinction trial than during the Post-acquisition trial. Finally, from the Post-extinction trial to the Spontaneous Recovery trial, it was expected that Sniffy would suddenly display more freezing behavior over time. Method Participants For the present study, 208 virtual rats (Sniffies) were recruited for observation. Materials The materials used in this experiment include the Sniffy Lite Program, pen, paper, computer, SPSS software, Microsoft Word, and Microsoft Excel.

THE EFFECT OF TRIAL TYPE

9

Procedure Beginning with the Pre-trial, a light (NS) was presented to Sniffy for 30 seconds in 1 trial. Moving onto the Acquisition trials, a light was presented for 30 seconds, with a shock given in the last second across 10 trials and 5 minutes set between each trial. In the Post-acquisition trial, only light was presented to Sniffy for 30 seconds. Moving onto the Extinction trials, only the light was presented for 30 seconds over the course of 20 trials where it can be seen that his freezing behavior declines. The interval between each trial was changed from 5 minutes to only 2 minutes. In the Spontaneous Recovery trials, after a 24-hour absence and returned back to the experimental environment, Sniffy showed freezing behavior again if he got shocked. Here, only the light (CS) was presented for 30 seconds with no shock for 15 trials with 2 minutes set between each of them. Data Analysis This present study utilized SPSS to measure descriptive statistics, which include the means, standard deviations, and paired sample t-tests. For the paired sample t-tests, the following pairings were examined: Pre-acquisition trial to Post-acquisition trial, trial 10 of the Postacquisition phase to trial 1 of the Extinction phase, trial 1 of the Extinction phase to trial 20 of the Extinction phase, trial 20 of the Extinction phase to trial 1 of the Spontaneous Recovery phase, and trial 1 of the Spontaneous Recovery phase to trial 15 of the Spontaneous Recovery phase. Results After conducting the paired sample t-tests for the five pairings, the following results were obtained: Sniffy froze significantly more during the Post-acquisition Trial than during the Preacquisition Trial, t(207) = -80.38, p < .05. There was no significant difference in Sniffy freezing

THE EFFECT OF TRIAL TYPE

10

from Trial 10 of the Post-acquisition phase to Trial 1 of the Extinction phase, t(207) = 1.37, p=.17. Sniffy froze significantly less while the light was on during Extinction Trial 20 than during Extinction Trial 1, t(207) = 33.85, p < .05. Sniffy froze significantly more during Spontaneous Recovery Trial 1 than during Extinction Trial 20, t(207) = -18.71, p < .05. Lastly, Sniffy froze significantly less while the light was on during Spontaneous Recovery Trial 15 than during Spontaneous Recovery Trial 1, t(207) = 22.30, p < .05. Significance was determined by evaluating the probability of significance (2-tailed). If the value was < .05, it meant that there was significant differences between the pairs of variables. As Table 1 shows, both the mean and standard deviation increased. In the Pre-trial, both were at 0, but then after the Post-trial, the mean increased up to 0.7 and the standard deviation increased up to 0.13. Table 2 displays the mean values for each trial of the three phases on freezing behavior learning. Figure 1 shows how shock trials affected freezing behavior, with the behavior being shown more during Post-trial than Pre-trial. Lastly, Figure 2 displays the effect of trial type on freezing behavior. During the Acquisition trials, Sniffy shows an increase in freezing behavior, yet decreases while put in the Extinction trials. The steady decrease in freezing behavior from Sniffy continues to show throughout the Spontaneous Recovery trials too. Discussion Based off the results presented from the study, it can be seen that the Sniffies froze significantly more during the Post-acquisition Trial than during the Pre-acquisition Trial. This shows that the Sniffies learned to respond more (freezing behavior) to the light in the Post Trial, giving evidence of Acquisition. During the acquisition trials, the light (NS) was repeatedly presented to Sniffy, causing a response and an association to form. The light turned from being the NS into the CS, with the learned response of freezing acquired. From the last trial of the

THE EFFECT OF TRIAL TYPE

11

Acquisition phase to the first trial of the Extinction phase, there was no significant difference because the learned response was still fresh in their mind. After 10 trials, the Sniffies were still expecting a shock to occur, causing them to freeze as the response. During the Extinction trials, the Sniffies froze significantly less when the light was presented because there was no shock presented. Here, the light (CS) was no longer paired with the shock (UCS), causing their once learned behavior of freezing to decrease. In the Spontaneous Recovery Trials, their behavior increased again because of the previous conditioning. After going through a resting period, the Sniffies weren’t sure of what to expect coming, so they just prepared for the worst when the shock was presented again suddenly, with the freezing behavior decreased during Spontaneous Recovery. The results of this study do align with the results of the studies described in the introduction section of the paper. Ratner and Miller (1959) found evidence of both Acquisition and Extinction for earthworms when they saw that the earthworms responded more in retraction when presented with the vibratory stimulus, yet responded less in retraction when the vibratory stimulus was taken away. Similar to Sniffy, his behavior increased when presented with the light, but decreased after removing the stimulus. In addition, Kellogg and Spanovick (1959) conducted a similar study that also found evidence of Acquisition for fish. Their study showed that there was an increase in percentage frequency of CR’s when presented with the stimulus. Again, similar to Sniffy, he displayed more response when given the stimulus during conditioning. The collective results from the Sniffy experiment and previous research show that the Sniffy results expand upon the articles, which found evidence of both Acquisition and Extinction. The Sniffy experiment expanded upon the articles in that it also found evidence of Spontaneous Recovery where the CR reappeared for Sniffy after a resting period. The Sniffy study and articles show

THE EFFECT OF TRIAL TYPE

12

experimental evidence that these 3 phases of classical conditioning exist and a learning association can form as well. Some ways that the current experiment could be improved include conducting the experiment on an actual rat, instead of a virtual one. By using a virtual rat, it would be uncertain if the behavior demonstrated would apply toward real rats. Other ways include using a control group to compare results and measuring more trials for reliability. Lastly, another way of improving the experiment would be access to more money. By having additional money, there would be access to the full Sniffy version instead of the lite program used. For the next investigation, a diff...