In this study, we examined the effects of social facilitation by self-image presentation on muscle and brain activities during the intake of a modified diet for dysphagia. Under the self- and wall-image conditions, participants ingested gelled green tea, and electromyography (EMG) and electroencephalography (EEG) of the suprahyoid muscles were carried out before and after swallowing. EMG during swallowing showed significantly higher activity under the self-image condition. There was no significant difference in the activities of alpha and beta waves in the EEG before swallowing started. After the start of swallowing, the EEG showed a significant decrease in alpha wave activity under the self-image condition. The beta wave activity was significantly higher under the self-image condition and the alpha wave activity was significantly higher under the wall-image condition. These results showed that the activities of swallowing-related muscles and the brain were altered after ingesting a modified diet for dysphagia during self-imaging.