Matching Items (3)
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- All Subjects: suppression
- All Subjects: Taste
- Genre: Doctoral Dissertation
- Creators: Capaldi Phillips, Elizabeth D
- Creators: Homer, Judith
- Creators: Karoly, Paul
Description
The use of bias indicators in psychological measurement has been contentious, with some researchers questioning whether they actually suppress or moderate the ability of substantive psychological indictors to discriminate (McGrath, Mitchell, Kim, & Hough, 2010). Bias indicators on the MMPI-2-RF (F-r, Fs, FBS-r, K-r, and L-r) were tested for suppression or moderation of the ability of the RC1 and NUC scales to discriminate between Epileptic Seizures (ES) and Non-epileptic Seizures (NES, a conversion disorder that is often misdiagnosed as ES). RC1 and NUC had previously been found to be the best scales on the MMPI-2-RF to differentiate between ES and NES, with optimal cut scores occurring at a cut score of 65 for RC1 (classification rate of 68%) and 85 for NUC (classification rate of 64%; Locke et al., 2010). The MMPI-2-RF was completed by 429 inpatients on the Epilepsy Monitoring Unit (EMU) at the Scottsdale Mayo Clinic Hospital, all of whom had confirmed diagnoses of ES or NES. Moderated logistic regression was used to test for moderation and logistic regression was used to test for suppression. Classification rates of RC1 and NUC were calculated at different bias level indicators to evaluate clinical utility for diagnosticians. No moderation was found. Suppression was found for F-r, Fs, K-r, and L-r with RC1, and for all variables with NUC. For F-r and Fs, the optimal RC1 and NUC cut scores increased at higher levels of bias, but tended to decrease at higher levels of K-r, L-r, and FBS-r. K-r provided the greatest suppression for RC1, as well as the greatest increases in classification rates at optimal cut scores, given different levels of bias. It was concluded that, consistent with expectations, taking account of bias indicator suppression on the MMPI-2-RF can improve discrimination of ES and NES. At higher levels of negative impression management, higher cut scores on substantive scales are needed to attain optimal discrimination, whereas at higher levels of positive impression management and FBS-r, lower cut scores are needed. Using these new cut scores resulted in modest improvements in accuracy in discrimination. These findings are consistent with prior research in showing the efficacy of bias indicators, and extend the findings to a psycho-medical context.
ContributorsWershba, Rebecca E (Author) / Lanyon, Richard I (Thesis advisor) / Barrera, Manuel (Committee member) / Karoly, Paul (Committee member) / Millsap, Roger E (Committee member) / Arizona State University (Publisher)
Created2013
Description
The unpleasant bitter taste found in many nutritious vegetables may deter their consumption. While bitterness suppression by prototypical tastants is well-studied in the chemical and pharmacological fields, mechanisms to reduce the bitterness of foods such as vegetables remain to be elucidated. Here tastants representing the taste primaries of salty and sweet were investigated as potential bitterness suppressors of three types of Brassicaceae vegetables. The secondary aim of these studies was to determine whether the bitter masking agents were differentially effective for bitter-sensitive and bitter-insensitive individuals. In all experiments, participants rated vegetables plain and with the addition of tastants. In Experiments 1-3, sucrose and NNS suppressed the bitterness of broccoli, Brussels sprouts, and cauliflower, whereas NaCl did not. Varying concentrations of NaCl and sucrose were introduced in Experiment 4 to assess the dose-dependency of the effects. While sucrose was a robust bitterness suppressor, NaCl suppressed bitterness only for participants who perceived the plain Brussels sprouts as highly bitter. Experiment 5, through the implementation of a rigorous control condition, determined that some but not all of this effect can be accounted for by regression to the mean. Individual variability in taste perception as determined by sampling of aqueous bitter, salty, and sweet solutions did not influence the degree of suppression by NaCl or sucrose. Consumption of vegetables is deterred by their bitter taste. Utilizing tastants to mask bitterness, a technique that preserves endogenous nutrients, can circumvent this issue. Sucrose is a robust bitter suppressor whereas the efficacy of NaCl is dependent upon bitterness perception of the plain vegetables.
ContributorsWilkie, Lynn Melissa (Author) / Capaldi Phillips, Elizabeth D (Thesis advisor) / Cohen, Adam (Committee member) / Johnston, Carol (Committee member) / Sanabria, Federico (Committee member) / Arizona State University (Publisher)
Created2014
Description
Given the continued increase in obesity rates in the United States, there has been growing research regarding factors related to obesity. Researchers have examined biological factors, such as set point theory, as well as various psychological factors such as motivation, self-efficacy, and eating styles. Taster-type, defined as how an individual experiences the perception of taste (particularly bitterness), is a recent area of research that has explored the potential relationship between this phenomenon and obesity. The current study examined whether taster-type impacted weight loss, along with secondary measures of BMI, waist circumference, and food neophobia, as well as taster-type’s impact on these measures over time. This study also examined the potential role of taster-type as a predictor of weight loss, independent of the psychological variables of motivation, self-efficacy, and eating styles. Ninety adult participants, consisting of 64 females and 19 males were recruited for this study. They were asked to diet for four weeks; 60 finished the full four weeks and completed psychosocial measures over two time periods. They were asked to record their food using an online food journal, attend weekly meetings for weigh-ins, and were given psychoeducational materials regarding factors affecting weight loss. The results indicated that taster-type was not a significant factor in BMI or waist circumference, but taster-type did interact with time to reveal that supertasters consistently lost weight across the four week dieting period while nontasters leveled off after Week 2. Additionally, both groups increased in food neophobia from the start of the dieting period to the end of Week 4. Consistent with previous research, motivation and self-efficacy predicted weight loss; however, taster-type did not increase the prediction of weight loss across the dieting period. This effect only occurred at Week 2. By Week 4, no psychosocial variables were significant predictors of weight loss.
ContributorsWagner, Melissa C (Author) / Robinson-Kurpius, Sharon (Thesis advisor) / Capaldi Phillips, Elizabeth (Committee member) / Homer, Judith (Committee member) / Arizona State University (Publisher)
Created2016