A recent study by the American Academy of Pediatrics found that 4 year olds who watched fast-paced cartoons, such as Sponge Bob Square Pants, had significantly less executive function than their control groups. They used 2 control groups; one that watched slower paced shows, and one that were given pencils and crayons to draw with.
From the study:
In addition to the pacing, we speculate that the onslaught of fantastical events that was also present in the fast-paced show might have further exacerbated EF (Executive Function). Whereas familiar events are en-coded by established neural circuitry, there is no such circuitry for new and unexpected events, which fantastical events often are. Encoding new events is likely to be particularly depleting of cognitive resources, as orienting responses are repeatedly engaged in response to novel events.41 Because cognitive depletion taxes self- regulation, we hypothesize that the fantastical aspect of the fast-paced show could also be partly responsible for the EF effects seen here. This hypothesis will be tested in further research.