Fig. 6: Results from Control Experiment 2 (Control Experiment 2; n = 17).
From: Neural mechanisms underlying the effects of physical fatigue on effort-based choice
a Exertion trial performance during the modified fatigue choice phase. Performance is represented as the mean repetitions required to successfully perform five exertions (successful trials need not be consecutive); higher values indicate more exertion trials were required in order to successfully exert at the target effort five times. Error bars indicate SEM. b Mean exertion during the modified fatigue choice phase. Mean exertion is presented in units of effort. Error bars indicate SEM. c Self-reported measures of participants’ state of fatigue over the course of the modified fatigued choice phase. The plot shows mean self-reported ratings of fatigue at the beginning and end of the 17 exertion blocks. Self-reported fatigue persisted when the exertion task returned to low effort trials after a two minute rest. Error bars indicate SEM. d Mean frequency of the power spectrum of EMGs between first and second low effort sections of the modified fatigue choice phase. The plot shows mean frequency measures from EMGs for all successful exertions averaged within the first and second low effort (10U) sections. Mean frequency of the EMG power spectrum decreased between first and second low effort sections (average change in mean frequency: −4.39 Hz; two-tailed paired-sample t-test: t16 = −2.25, p = 0.04). Error bars indicate SEM. *p = 0.04. e Histograms of the parameter-space posteriors from the hierarchical Bayesian model estimating changes in effort subjectivity parameters (Δρ) between the different sections of the modified fatigue choice phase. The population exhibited an increase in effort subjectivity parameters (ρ) during choices intermixed with high effort exertions, as compared to the first session of 10U low effort exertions (60U; ρ60U–ρ10U,1; dark gray). This shift in effort subjectivity remained even after returning to low effort exertions (10U;ρ10U,2–ρ10U,1; light gray). The solid black lines indicate the bounds of the 95% highest-density interval for each distribution, both of which exclude 0 (indicated with the dashed black line).
