How do we understand the emotional content of written words? Here, we investigate the hypothesis that written words that carry emotions are processed through phylogenetically ancient neural circuits that are involved in the processing of the very same emotions in nonlanguage contexts. This hypothesis was tested with respect to disgust. In an fMRI experiment, it was found that the same region of the left anterior insula responded whether people observed facial expressions of disgust or whether they read words with disgusting content. In a follow-up experiment, it was found that repetitive TMS over the left insula in comparison with a control site interfered with the processing of disgust words to a greater extent than with the processing of neutral words. Together, the results support the hypothesis that the affective processes we experience when reading rely on the reuse of phylogenetically ancient brain structures that process basic emotions in other domains and species.

Event-related brain potentials (ERPs) to words, pseudowords, and nonwords were recorded in three different tasks. A letter search task was used in Experiment 1. Performance was affected by whether the target letter occurred in a word, a pseudoword, or a random nonword. ERP results corroborated the behavioral results, showing small but reliable ERP differences between the three stimulus types. Words and pseudowords differed from nonwords at posterior sites, whereas words differed from pseudowords and nonwords at anterior sites. Since deciding whether the target letter was present or absent co-occurred with stimulus processing in Experiment 1, a delayed letter search task was used in Experiment 2. ERPs to words and pseudowords were similar and differed from ERPs to nonwords, suggesting a primary role of orthographic and phonological processing in the delayed letter search task. To increase semantic processing, a categorization task was used in Experiment 3. Early differences between ERPs to words and pseudowords at left posterior and anterior locations suggested a rapid activation of lexico-semantic information. These findings suggest that the use of ERPs in a multiple task design makes it possible to track the time course and the activation of multiple sources of linguistic information when processing words, pseudowords, and nonwords. The task-dependent nature of the effects suggests that the language system can use multiple sources of linguistic information in flexible and adaptive ways.