Caffeine improves text reading and global perception

In the world, 1.6 billion cups of coffee are daily consumed. Does this psychostimulant affect our everyday activities, such as reading? Caffeine seems to enhance the global perception of a visual scene. Global perception - mainly controlled by the right magnocellular-dorsal pathway - is causally connected to reading abilities, because it longitudinally predicts future reading development in pre-reading children and behavioral interventions that increase its efficiency directly improves reading skills. Consequently, caffeine intake - facilitating the global perception - could improve reading performance. Here, we demonstrate that in low and normal coffee consumers a single dose of 200 mg of caffeine substantially accelerates the word text reading speed without any effect on alerting, attentional orienting, executive and phonological functions. We tested, in a large sample of participants, several reading skills, global and local perception, alerting, spatial attention, and executive functions as well as rapid automatized naming and phonological memory, using a double-blind, within-subjects, repeated-measures design in a feasibility and a mechanistic study. We found that caffeine improved adults’ reading speed of meaningful sentences, whereas word text single word/pseudoword, or pseudoword text reading abilities were not modified. This effect of caffeine on reading ability resulted boosted by small sleep deprivation. Importantly, global perception of visual scene also improved only after caffeine assumption. These findings could have important implication for better comprehension of dyslexia.