<p>Using smart devices to calm or occupy toddlers during tantrums could stunt their healthy emotional development and make them more volatile over time, a study shows.</p> <p>Five researchers published the study of 422 parents and their children ages 3-5 in JAMA Pediatrics on Monday. Conducted from August 2018 to January 2020, it found that children soothing themselves with smartphones or tablets made poorer decisions and became more explosive after three- and six-month intervals.</p> <p>Responding on a 5-point scale to a questionnaire, the parents of boys and high-spirited children reported the sharpest cognitive declines in executive functioning and spikes in emotional reactivity.</p> <p><br></p> <div class="bigtext">&nbsp;</div>