Chairperson, Graduate Committee: Keith A. HutchisonHood, Audrey Victoria Blackwell2023-10-182023-10-182023https://scholarworks.montana.edu/handle/1/17868The current dissertation sought to 1) examine the relationship between working memory capacity (WMC), attention control, and high-frequency heart rate variability (HF-HRV) and 2), to implement an HRV biofeedback training with the goal of increasing resting baseline HF-HRV, and in turn, attention control task performance. In both experiments, physiological measurements were collected during a seated, resting baseline using electrocardiograph electrodes and BioNomadix receivers which transmitted signals to a BioPac MP-150/160 System. The HRV index used in this study was calculated from the inter-beat intervals and inter-breath intervals data extracted from the electrocardiograph and respiration signals. In Experiment 1, participants first underwent a resting baseline period to assess their HRV and then completed two WMC tasks. Experiment 2 took place during two laboratory sessions with a week-long at-home training between lab Sessions 1 and 2. At Session 1, participants first underwent a resting baseline period to assess their HRV and then completed two measures of WMC. They then completed three attention control tasks pre- and post-training. For the training, those randomly assigned to the HRV biofeedback condition underwent a breathing exercise, whereas those randomly assigned to the active control condition completed wordsearch puzzles. Participants were asked to practice the breathing/wordsearch exercises at home for one week. At Session 2, participants underwent a resting baseline physiological assessment followed by the three attention control tasks again. Results demonstrated that HF-HRV is weakly correlated with WMC and attention control and that brief, 5-minute sessions of HRV biofeedback are not sufficient to increase levels resting baseline HF-HRV.enShort-term memoryAttentionHeart beatBiofeedback trainingDissertationCopyright 2023 by Audrey Victoria Blackwell Hood