Senior Theses: 2002-2003

Influence of Linoleic Acid on Taste Intensity in HumansMary Holland Brumbach, Virginia Clyburn, Hailey Hughes, Sean Patterson,Krysta WebsterFaculty Advisor:Dave Pittman, Ph.D. 

Human and rat have an innate preference for fat which may lead to obesity.  This preference may be driven by the taste component linoleic acid, the principle free fatty acid found in corn oil.  It has been shown that rats are capable of detecting linoleic acid within a solution.  It is speculated that rats also perceive an increase in intensity when linoleic acid is added to the solution.  This experiment sought to measure the effect on human taste intensity when linoleic acid was added to sweet stimuli.  Using a sip and spit method, subjects rated the intensity of a triad, each containing a different amount of linoleic acid (0, 88, or 352 mM) mixed with either sucrose or sucralose (31, 62, 125, 250, 500 mM).  There was no effect of linoleic acid on the perceived intensity of the sweet stimuli.  However, there was a difference in perceived intensity between the two sweet stimuli.  Sucrose was perceived as more intense than sucralose at the 125 and 500 mM concentrations.  Body mass index (BMI) and percentage of body fat are two measures of obesity.  If taste plays a role in producing obesity, BMI and percentage of body fat would have a positive correlation with taste intensity of sweet stimuli.  No correlation was found between either percentage of body fat or BMI and the intensity of the sweet stimuli.  Although the current methodology did not measure an effect of linoleic acid, different threshold and discrimination procedures such as forced choice rating system may produce more conclusive data.

In Search of Behavioral Momentum Within Simultaneous Stimulus ArraysKristina Autry, Jeffrey Labban, and Jessica Miles
Faculty Advisor: Alliston K. Reid, Ph.D.

This experiment sought to determine if Behavioral Momentum Theory (BMT) could be applied to simple response sequences in simultaneous arrays. Four pigeons were trained on a three-response simultaneous stimulus array. After training, the subjects were switched to an experimental condition in which preference and resistance to change were measured in the initial and terminal response positions of the sequences. The hypothesis that the initial response position would be less resistant to change than the terminal position was rejected. The results of this experiment were compared to the results of Catoe, Kiehne, & McCormack (2002) (see abstract below) which utilized successive stimulus arrays, to determine if learned value is acquired in a similar manner with both arrays. The results from the present experiment replicated the results from the earlier study, further contradicting predictions based on a delay-of-reinforcement gradient. The similarity of the results in each experiment suggests that value is transmitted similarly within each type of array, but in an unexpected manner.

Catastrophizing and Pain: The effects of video manipulation on expected pain and willingness to endure pain
Courtney Bartie, Jesse McCoy, Brandon Smith, and Trisha Stanley
Faculty Advisor: John C. Lefebvre, Ph.D.

Davey and Levy (1998) have proposed that the genesis of catastrophic thinking may lie in the process by which individuals progressively imagine worse outcomes to a specific topic.  Research has shown that greater levels of catastrophizing are related to greater levels of emotional distress and the experience of pain (Sullivan et al, 20001).  Theoretical approaches have proposed that catastrophizing can be seen as either state-like (variable, situation-based response to pain) or trait-like (stable, dispositional characteristic).  The goal of the present study was to determine the flexibility of catastrophizing by assessing the effects of a video manipulation on both forms of catastrophizing, expected pain, and the willingness to endure pain for money.  The current study involved 40 participants who completed a series of pre and post-test measures including the Catastrophizing State Scale (CATS), the Pain-Catastrophizing Scale (PCS), a measure of expected pain, and a measure that asked individuals to report how long they would be willing to tolerate pain for different amount s of money.  Participants were randomly assigned to one of two video treatment conditions (non-catastrophizing or catastrophizing).  Participants were then asked to submerge their non-dominant forearm for 2 minutes and reported on their level of pain.  The results found no significant effect of video manipulation on reported levels of catastrophizing or on pain reports.  The study concludes with a discussion of the results and possible future directions.

Prenatal Behaviors and Obstetric Outcome
Rebecca Chapman, Lauren Marie Whisenhunt, McLane Linton, and Jennifer Stokes
Faculty advisor: C. B. McAninch, Ph.D.

The effects of preterm birth are not only detrimental at delivery, but also may spawn problems during the future development of the child.  Therefore, all factors (e.g., smoking, alcohol, or drug use) contributing to the risk of preterm birth should be analyzed; however, the risk that certain sexual behaviors may be present is unclear at this time.  Due to limited, contradictory research, it was hypothesized that sexual intercourse may be associated with preterm birth.  Survey data were gathered from subjects at a maternal-fetal medical clinic, which recorded the frequency of behaviors during the month prior to pregancy as well as the most recent month during pregnancy.  Delivery data (e.g., gestation length, type of delivery, and complications) were obtained from hospital records.  Due to the small sample size and a limited number of births by the end of this study, no firm conclusions could be drawn, but the study is ongoing. 

Taste Modulation by Linoleic Acid in RatsSarah Elizabeth Cheek, Steven Dwight Robinson, and Dylan Burr Scott
Faculty Advisor:Dave Pittman, Ph.D. 

Fat detection is an important part of taste preference, especially if the fat produces a change in the consumption of food.  The disturbing rise in overweight individuals has prompted researchers to understand the underlying motivation behind overeating.  Sensory mechanisms have been linked to over consumption and taste has been demonstrated to play a key role in food preference.  Four general tastant qualities are recognized by the taste system.  Studies suggest that free fatty acids contained in fat may affect taste receptor cells.  Gilbertson (1998) found that free fatty acids modulate K+ channels and increase cell depolarization.  This experiment defined the ability of linoleic acid to modulate tastant intake.  Linoleic acid was added to solutions representative of the four tastant groups (sweet, sour, bitter, and salty) to determine if the presence of a free fatty acid can alter the licking performance of rats. Results from the experiment show that linoleic acid does alter the licking performance in rats.  The licking performance was increased in sucrose, citric acid, and quanine, while licking was decreased in sodium chloride.  With these results, human applications can be derived perhaps ultimately as a combatant of the effects of fat intake on obesity.

Catastrophizing and Pain: The Effects of a Video Manipulation
Tori Swanson, Kymm Brown, Andrea Peabody, and George LehrFaculty Advisor: J. C. Lefebvre, Ph.D. 

Catastrophizing is a negative set of cognitions that have been shown to influence the expression of pain. Although early studies demonstrated that catastrophizing was situation specific, more recent studies have emphasized more trait-like characteristics. The study involved forty undergraduates (20 female and 20 male) who were given the CATS, PCS, measure of expected pain and hypothetical monetary scales. Participants were randomly assigned to watch either a video of catastrophizing behavior or stoic behavior during a pain induction procedure (cold pressor task). Analyses demonstrated that the videos had a differential effect for scores on the CATS and expected pain measure. The results suggested that participants who watched the catastrophizing video showed an increase in CATS and expected pain while those in the stoic video went in the opposite direction. These results suggest that catastrophizing can be manipulated and is related to changes in pain.

In Search of Behavioral Momentum Within Successive Chains
Rebecca Catoe, Klaire Kiehne, and Danielle McCormackFaculty advisor: Alliston K. Reid, Ph.D. 

This experiment sought to apply Behavioral Momentum Theory (BMT) to simple response sequences by exposing pigeons to a two-component multiple schedule. In the Sequence component, pigeons earned food by completing a sequence of three responses to colored keys presented in succession. This component served to create and maintain differences in the response strengths of pecks to red and white keys, which occurred at the initial and terminal positions of the required response. The key lights were turned off for three seconds following the initial and middle responses in order to increase the difference in value between the initial and terminal responses. The Preference component served to measure these differences in value or response strength. This difference was measured by comparing concurrent response rates on red and white keys, both reinforced by a single variable interval schedule. After baseline response rates were obtained, resistance to change was measured by providing free food during the blackout periods on a variable time (VT) 20-second or VT-8s schedule. Obtained baseline response rates were generally higher to the key color representing the initial response in the sequence than to the color representing the terminal response. Contrary to the predictions of BMT, in seven of eight conditions responding to the initial response key was more resistant to change than was responding to the key color representing the terminal response.