Date of Completion
4-20-2022
Degree Type
Honors Thesis - Campus Access
Discipline
Psychology (PSYC)
First Advisor
Dr. Kayoko Okada
Abstract
The existence of an internal detection or “monitoring” system for speech production has been suspected for some time, however it has never been directly researched. While not the main focus of their study, a recently published FMRI experiment, Okada et al. (2018) found suggestive evidence for such a mechanism in the posterior middle temporal gyrus (pMTG), a region of the brain implicated in lexical-level processes. In the study, they asked participants to recite tongue twisters that tend to generate slips of the tongue. Half of the trials involved stimuli that biased the errors toward real words and half biased errors toward non-words. They found that the brain nonetheless distinguished between error-type conditions – nonword biased trials resulted in more activity than word biased trials – a process called the lexical bias effect. Interestingly, the participants’ imaging data showed this distinction through pMTG activation, a region that is known to involve lexical-semantic level processing. In other words, the mere potential for a nonword error engaged this neural network, even when no error was committed. The present study sought to build upon this suggestive evidence with the addition of a ‘taboo tongue twisters’ condition. The additional condition was developed in order to directly tax the error correction mechanism in that the participants would become extremely alert to their potential to generate a taboo word error. During these error correction trials, we did identify significant posterior medial temporal gyrus (pMTG) activation as seen in Okada (2018). Additionally, we identified significant bilateral activation in the angular gyri, a brain region that is known to be involved in semantic processing. Therefore, suggesting that both the pMTG and the angular gyri are involved in a speech error correction mechanism.
Recommended Citation
Murphy, Emma and Okada, Kayoko, "Identifying Speech Error Correction Mechanism in the Brain" (2022). Honors Thesis. 552.
https://digitalcommons.lmu.edu/honors-thesis/552
