Johnson observed that watching TV does not require the use of imaginative thinking because the viewer passively takes in pictures on the screen (2). When children read, however, they generate their own mental images

Television (TV) viewing is known to affect children's verbal abilities and other physical, cognitive, and emotional development in psychological studies.

We also confirmed negative effects of TV viewing on verbal intelligence quotient (IQ) in cross-sectional and longitudinal analyses.

Reported in the Journal of Genetic Psychology was the finding that children’s television viewing ‘resulted in an eventual decrease in their academic achievement.

researchers compared high I.Q. students who were heavy TV watchers with equally bright students who watched little TV.  They found significantly higher scores on a reading comprehension test among the low TV viewers.

Professor Herbert Krugman found that within 30 seconds of turning on the television, our brains become neurologically less able to make judgements about what we see and hear on the screen.