A small quantity of caffeine accelerates the reading speed of text, according to new research published in the Journal of Psychopharmacology. The observed improvements in reading speed were also accompanied by a change in the overall perception of visual stimuli.

“While studying the cause of developmental dyslexia — the inability to acquire adequate reading abilities — we observed that children with dyslexia show a specific deficit in the analysis of whole visual images, showing a tendency to focused on local details,” explained study author Sandro Franceschini of the University of Padova in Italy.

“In rehabilitation trainings, we observed that improving their global analysis of visual scenes also improved their reading skill. Knowing that caffeine could momentarily improve the global perception of visual scenes in healthy adults, we were interested to measure if this ‘magnification’ of global perception was linked to an improvement of reading skills.”

In two double-blind studies involving 78 participants, the researchers found that a single dose of 200 mg of caffeine (about two espresso coffees) significantly improved the reading speed of text compared to placebo.

In line with previous research, caffeine also improved global pattern perception — meaning the ability to distinguish large letters composed of smaller letters.

The findings highlight that “many different factors contribute to the execution of a complex ability like reading a text, not only phonological skills. Visual perception and attention could play a determinant role,” Franceschini told PsyPost.

The researchers also found that a small amount of sleep deprivation was related to greater beneficial effects.

“Our results show that the effect of caffeine on meaningful word text reading speed was boosted by a small amount of sleep deprivation: if in the previous night one loses two hours of sleep, then the savings when reading this article will be more than doubled,” Franceschini explained.

“It is intriguing to think that caffeine, to boost its effect, needs a specific brain condition. This correlation could drive future research to establish the effect of caffeine on specific neurotransmitters.”

The researchers did not observe speed improvements in the reading of single word lists or nonsense words. “Improvement in text reading speed did not appear to be due to a faster decoding of the single elements that compose the string of letters or a faster access to phonological lexicon,” the authors of the study wrote.

Caffeine also did not boost phonological short-term memory or executive functions.

“We would like to understand the specific network activated by caffeine intake. Global perception is usually associated with right hemisphere abilities. At the same time, we know that the right hemisphere does not host phonological information. We need to understand specifically in what way this network exerts its influence,” Franceschini said.

The study, “Caffeine improves text reading and global perception“, was authored by Sandro Franceschini, Matteo Lulli, Sara Bertoni, Simone Gori, Alessandro Angrilli, Martina Mancarella, Giovanna Puccio, and Andrea Facoetti.