1. Introduction Results Discussion Method References
 Operant Sound Discrimination In Rats
Emily Fincher & Laura Phillips
Randolph College
Lynchburg, VA 24503
Introduction
According to Chase (2006), operant learning is when an organism’s behavior is strengthened or weakened as a result of the consequences for that behavior. Positive reinforcement is an operant procedure where behavior is strengthened because of the introduction of an appetitive stimulus.
Discrimination is when a behavior is more likely to occur in one situation but not in others (Chase, 2006), such as when sound is present. In operant discrimination training, sound could be a stimulus that indicates the availability of a reward if the correct behavior is performed.
Past research has shown that it is possible for animals to learn to discriminate between different types of music, such as the study by Porter and Neuringer (1984) using pigeons. The study found that pigeons were able to discriminate between the music of Bach and Stravinsky.
Through operant discrimination training, the researchers hope to determine if it is possible for rats to discriminate between music and white noise.
Figure 1
Results
A paired samples t-test showed a significant decrease in latency to dig between the first trail day (M=13.63, SD=9.04) and the last trail day (M=48, SD=30.69), t(7)=-3.36, p=.01.
By the fourth day, both subjects had achieved a 50% correct cup choice.
For the test trial the preference index scores were compared to chance (.33). Only one trial exceeded chance, with a score of .53. A paired samples t-test of all preference scores (M=.30, SD=.16) show no statistical significance, t(3)=-.40, p=.72.
Discussion
While the statistics show that the subjects were able to learn reinforcements were available, they did not show any discrimination to sound. Although, past research has shown that it is possible for animals to learn to discriminate between different types of music, the results of this study were not conclusive.
The procedure used for the two rats differed in the with one rat receiving pre-exposure and the other receiving one additional training day.
Future research might investigate whether it is easier for subjects to learn the difference between two types of music instead of one type of music and white noise.
Method
Subjects
The subjects used were two adult male, Long Evans rats obtained from the Harlan Breeding Company. The subjects were placed on food deprivation and their weight was maintained at 85% of their free-feeding weight and water was available ad libitum.
Apparatus
The apparatus used was a T-maze consisting of three arms of equal lengths. One sand filled cup was placed at the end of each of two arms, one of which contained the reward (Fruit Loops). A CD with three tracks was used, the first track consisting of both music and white noise, the second track consisting of music alone, and the third with white noise.
Procedure
At the beginning of the experiment, one rat (Ivan) was exposed to the maze for five minutes while the first track played with no cups or rewards. The second rat (Mick) was not given a habituation period.
Ivan received four training days and Mick received five.
In all trials, the reward was placed in the left arm when music was played, and placed in the right arm when white noise was played. Latency to dig and first cup choice was recorded.
All training and shaping days consisted of four trials, counterbalanced, and the rats were given a maximum of five minutes to retrieve at least 5 fruit loops.
The first day consisted of shaping with the reward first exposed and then gradually buried until it reached a shallow depth. The depth remained constant throughout the training.
The testing day consisted of two trial—one for music and the other for white noise—and the rats were given three minutes in the maze. The time spent in each arm was recorded as well as latency to dig and first cup choice.
Figure 2
References
Chance, P. (2006). Learning and behavior: Active learning edition (5th ed.). Belmont, CA: Thomson/Wadsworth.
Porter, D., & Neuringer, A. (1984). Music discrimination by pigeons. Journal of Experimental Psychology: Animal Behavior Processes, 10,