Operant Conditioning - Essay Example

?Operant Conditioning Introduction Many studies have shown that individual stimuli can control responses by operant conditioning, and there have beenattempts to show that a combination of these stimuli will give a greater response than when taken individually. The purpose of the current study is to explore the effects of both odor and tone on naive rats in a laboratory setting to ascertain how these stimuli, when combined, affect rat behavior above the free operant baseline. The experiment was conducted on four naive rats kept under strictly controlled conditions, each identical to the other to preserve any bias towards any one situation. Overall, the aim of the study was to explore how the different stimuli outlined above work in combination with each other to provide a response leading to certain behaviors in rats, possibly with the overall aim in uncovering how these responses may be similar in other animals. Evidently, in reality, animals are rarely subjected to merely one stimuli or set of stimuli, and therefore understanding how these work both individually and cumulatively is important in gaining a proper understanding of operant conditioning and behavior in response to sets of stimuli. Methods The methods for this study are complex. The subjects for the testing were, as previously mentioned, four naive rats who had their weight reduced to 75-80% of their free-feeding weight. The main apparatus used was custom-made for the experiment with the aim of promoting the olfactory stimulus aspect of the testing. The chamber was linked to equipment which released smell. This smell was released by an olfactometer which was programmed to release the scent through a valve which limited and regulated the amount and strength of the smell, promoting equality between the different rat conditions. Measures were also taken to prevent other olfactory stimulation being present in the chamber which may act to alter the testing results. Additionally, the chamber contained a microswitch lever which, when pushed, dispensed a pellet of food to the rats. There was also equipment for promoting the auditory signaling, which was given out using a speaker which was similarly controlled to ensure validity. The rats themselves were given pre-experimental training, with rats O-1 and O-2 being exposed to training using the odor stimulus and O-3 and O-4 being trained using the sound stimulus. This was done in such a way that rats were exposed to either stimulus in an identical manner, and to promote the identification of the stimulus with the food. All rats were then exposed to three-ply multiple schedule sessions in which they were exposed to both stimuli separately as well as having neither stimulus. After the extensive training the rats were then exposed to the combination of tone and odor for the first time and their responses were measured. Details This study provides an immense amount of detail when describing the experimental methods and the results from the operant conditioning. There is no clearly stated hypothesis in this work, but the authors have explored the work on additive summation in operative conditioning with previous combinations of stimuli and recognize the importance of olfactory stimuli in rats, therefore suggest that there may be a similar additive element when combining smell and tone. The subjects are the naive rats as described above, and there is no control group although the investigation did measure the rat’s responses to the stimuli separately before the experiment during the training period. This information was recorded and noted in the test, therefore the control group could be said to be the rats prior to training. Evidently, the operational definition in this case of the rat’s response to stimuli is how they interact with the lever supplied that dispenses food. This is important, as there is no neurological imaging aspect to the testing so this behavior is assumed to be directly linked to the brain response to noise and smell stimuli. Similarly, the independent variable in this testing is the stimuli to which the rats are exposed to, whether this is smell, sound or a combination. The dependent variable, therefore, is the response to these stimuli, and the strength of the response, that the rats give to stimuli. As this was a complicated study dependent on multiple training factors, the results are similarly complicated. Firstly, and perhaps most importantly, it is noted that all four rats included for testing responded more to the combination of T+O than they did to either T (tone) or O (odor) separately, suggesting that the hypothesis that combinations of stimuli have a stronger effect than single stimuli. It is also noted that each of the four rats had slightly different rates of response to T and O, suggesting that there are individual differences in response to stimuli, as would be expected. However, despite these differences, the cumulative effect of T+O remained statistically significant. Additive summation was therefore observed in all four rats, despite their individual differences and the effort taken to train them. In conclusion, it seems evident that the study was complex in methods, particularly to train the rats to have the desired response, but had the desired effect of ascertaining that additive summation is found in T and O stimuli as previous studies have found for light and sound. Comments This study has a clear relationship with traditional operant conditioning. In this study, the rats have made an association between a stimuli and their behavior. During the training, it became obvious to the subjects that the stimuli was linked to the dispense of food, and that this dispense of food was in turn linked to the lever, so all three elements were in place to be linked. From here onwards, the rats were free to associate the behavior (the lever), the reward (the food pellet) and the stimuli (odor or tone). In this case, operant conditioning occurs when the stimuli is present – food is dispensed when the rat presses the lever and the tone or odor is present, whereas the absence of the stimuli leads to no response when the lever is pressed. This is an interesting adaption involving the use of an extinction condition to help reinforce the behavior. There are also some elements of classical or Pavlovian conditioning involved in this study. For example, combining a certain stimuli with a natural behavior (in this case, retrieving food) is similar to the Pavlovian theory of the conditioned stimulus. The tone or odor in this case acts as the conditioned stimulus, whereas the neutral stimulus is pressing the lever, as this was introduced to the rats before the official testing period began. The conditioned response is, therefore, pressing the lever in response to the tone or odor. Read More