Professors Dagmar Divjak and Petar Milin from the University of Birmingham conducted a study that found a correlation between bad grammar and heart rate variability (HRV). Essentially, the more grammatical errors a person hears, the more regular their heartbeat becomes, indicating stress. This study is unique in that it shows the relationship between language cognition and the autonomic nervous system (ANS), specifically the sympathetic (SNS) and parasympathetic (PNS) systems. The findings suggest that cognitive effort affects the physiological system in more ways than previously thought. HRV could potentially be used as an indicator of implicit linguistic knowledge and could help assess cognitive abilities in individuals who cannot verbally express their opinion.
https://www.birmingham.ac.uk/news/2023/hearing-bad-grammar-results-in-physical-signs-of-stress-new-study-reveals