Fear of Falling and Balance Confidence in Older Adults with Diabetes Mellitus

Several determinants of fear of falling (FoF) and low balance confidence overlap with the consequences/complications of diabetes mellitus (DM). FoF is strongly associated with low balance confidence, and balance confidence mediates the relationship between FoF and balance and physical function. The purpose of this thesis was two-fold: (1) to examine the prevalence, severity and determinants of FoF in older adults (aged≥65) with DM, and (2) to evaluate the validity of the short version of the Activities-specific Balance Confidence scale (ABC-6) and its association with balance and postural control in older adults with DM. Three separate studies were conducted of older adults with DM (DM-group) and without DM (noDM-group). Study I revealed that although FoF prevalence adjusted for age and sex was not different between-groups, the DM-group had 8.8% fewer participants in the low and 8.4% more in the high Falls-Efficacy Scale International categories when compared to the noDM-group. Higher FoF severity in the DM-group was associated with poor physical performance, being female, fall history and clinical depressive symptoms. Study II provided evidence of convergent, discriminant and concurrent validity of the ABC-6 for use in older adults with DM with and without diabetic peripheral neuropathy (DPN). Notably, the ABC-6 was more sensitive in detecting subtle differences in balance confidence between the DM-group and noDM-group when compared to the original ABC scale (ABC-16), and can be administered in less time. Study III explored balance confidence (ABC-6) and its association with balance and postural control in older adults with DM. Subtle differences in axial segmental control (i.e., lower trunk roll velocity and higher head-trunk correlations) while walking and lower balance confidence were apparent in the DM-group, even in the absence of DPN, when compared to the noDM-group. Balance confidence partially explained the variance in head-trunk stiffening between-groups, and consequently low balance confidence in older adults with DM may contribute to the dependence on postural control strategies that are normally only utilized in high-risk situations. Findings from this thesis will help to guide the development of protocols for screening and intervention recommendations of patient education and targeted rehabilitation programs for older adults with DM.

Investigating Multiple Roles of Vocal Confidence in Persuasion

Although persuasion often occurs via oral communication, it remains a comparatively understudied area. This research tested the hypothesis that changes in three properties of voice influence perceptions of speaker confidence, which in turn differentially affects attitudes according to different underlying psychological processes that the Elaboration Likelihood Model (ELM, Petty & Cacioppo, 1984), suggests should emerge under different levels of thought. Experiment 1 was a 2 (Elaboration: high vs. low) x 2 (Vocal speed: increased speed vs. decreased speed) x 2 (Vocal intonation: falling intonation vs. rising intonation) between participants factorial design. Vocal speed and vocal intonation influenced perceptions of speaker confidence as predicted. In line with the ELM, under high elaboration, confidence biased thought favorability, which in turn influenced attitudes. Under low elaboration, confidence did not bias thoughts but rather directly influenced attitudes as a peripheral cue. Experiment 2 used a similar design as Experiment 1 but focused on vocal pitch. Results confirmed pitch influenced perceptions of confidence as predicted. Importantly, we also replicated the bias and cue processes found in Experiment 1. Experiment 3 investigated the process by which a broader spectrum of speech rate influenced persuasion under moderate elaboration. In a 2 (Argument quality: strong vs. weak) x 4 (Vocal speed: extremely slow vs. moderately slow vs. moderately fast vs. extremely fast) between participants factorial design, results confirmed the hypothesized non-linear relationship between speech rate and perceptions of confidence. In line with the ELM, speech rate influenced persuasion based on the amount of processing. Experiment 4 investigated the effects of a broader spectrum of vocal intonation on persuasion under moderate elaboration and used a similar design as Experiment 3. Results indicated a partial success of our vocal intonation manipulation. No evidence was found to support the hypothesized mechanism. These studies show that changes in several different properties of voice can influence the extent to which others perceive them as confident. Importantly, evidence suggests different vocal properties influence persuasion by the same bias and cue processes under high and low thought. Evidence also suggests that under moderate thought, speech rate influences persuasion based on the amount of processing.