How to get your kids to listen to (and to actually do) what you say is one of the most frustrating and difficult parts of being a parent. A new study , published this month in the journal Pediatrics, has shed some light on trends in how parents are choosing to discipline their children these days. The researchers found that nonviolent forms of punishment are on the rise, and that the use of spanking and hitting as discipline has decreased.For the study, researchers looked at four national surveys, spanning 23 years of data, and found that, in 1988, 46% of mothers in middle-class families (which the researchers defined as those living in the 50th income percentile) said they used spanking as discipline. By 2011, that number had dropped to 21%. In that same period of time, the number of moms who regularly put their kids in time-out increased from 41% to 81%.When looking at all socioeconomic groups of mothers, the researchers found that spanking was found to be on the decline in general. However, among mothers in the lowest income percentile, one third said they spank their kids.The researchers called this finding "alarming" for several reasons . Besides the risk of serious injury, corporal punishment has been found to have negative emotional effects on children, and it can lead to physical abuse in some cases. The American Academy of Pediatrics advises against using spanking or hitting as a form of discipline.The fact that lower-income women often reported resorting to spanking reflects a lack of resources more than anything else, the researchers say. Not all parents have access to or are aware of the AAP's approved guidelines for effective discipline . A 1996 study found that the majority of parents who spank their children do so when they're stressed or angry — and they feel remorse afterward. In other words, spanking is rarely a thoughtful, pre-planned form of discipline — more often than not, parents resort to it when they're out of options.The researchers acknowledged that the stigma around spanking could be what's really driving the results. Fearing judgment, some parents may have simply reported they don't resort to spanking their children when, in reality, they still do. "What people say they do and what they actually do are two different things," psychology professor Christopher Ferguson, who was not affiliated with the study, told Live Science.