What is it about?

We tested whether non-invasive electrical brain stimulation (tDCS) can change how quickly people perform rapid naming of colors, letters, numbers, and combinations. Sixty healthy young adults named these visual stimuli as fast as possible before and after 20 minutes of stimulation. We found that excitatory stimulation made people perform all naming tasks faster, while inhibitory stimulation slowed them down. Sham (fake) stimulation had no effect, confirming these results. Interestingly, accuracy did not change—only speed was affected. This suggests brain stimulation can modulate naming speed without affecting accuracy in healthy adults.

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Why is it important?

We targeted the temporo-parieto-occipital junction—a brain region that integrates visual, language, and attentional processes critical for rapid naming. This is the first study to systematically investigate the effects of non-invasive brain stimulation on rapid naming across multiple categories (colors, letters, numbers, and combinations) in healthy young adults. We demonstrated bidirectional effects—excitatory stimulation speeds up performance while inhibitory stimulation slows it down. Importantly, we showed that speed can be modulated even when accuracy remains unchanged, suggesting that time-based measures are key for detecting stimulation effects. These findings provide a foundation for developing brain stimulation therapies targeting naming difficulties in aphasia, dementia, and age-related cognitive decline.

Perspectives

I'm grateful to have worked with such dedicated colleagues on this study. I find it fascinating that a simple 20-minute brain stimulation session can change how fast we name things. Our healthy young adults performed at ceiling-level accuracy, which likely explains why only speed was affected—but this excites me even more. Many people struggle with word-finding: the frustrating tip-of-the-tongue moments that increase with aging, the severe difficulties in aphasia and dementia, even the slow lexical access that second language learners experience. tDCS targeting the TPO junction might benefit all these populations. I hope this work inspires future research to test whether tDCS can help these groups—perhaps improving not just speed, but also accuracy where it's impaired.

Asst. Prof. Özlem Öge-Daşdöğen
Istanbul Atlas University

Read the Original

This page is a summary of: Effects of Transcranial Direct Current Stimulation on Rapid Automatized Naming Performance in Healthy Individuals, Journal of Speech Language and Hearing Research, December 2025, American Speech-Language-Hearing Association (ASHA),
DOI: 10.1044/2025_jslhr-25-00039.
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