Cognition is handled by the cerebral cortex, which is a tool of reasoning; it is a sophisticated tool, but it hasn’t yet been polished by evolution and therefore it’s pretty slow. It requires more effort to process information. Raw visual information is processed by the thalamus, a much older part of the brain than the cerebral cortex. It takes only a few hundred milliseconds to process visual stimuli (much faster than we process text or numbers). So, processing visual data is faster, and it reduces the cognitive load. We’re not aware of the amount of data and the speed with which we process visual information. It’s subconscious. This phenomenon is known as “pre-attentive processing”.
Elena V Kazakova, The Psychology behind Data Visualization Techniques
