Jason hit Barnes and Noble in NYC Wednesday to promote his new book "Sing Your Name Out Loud: 15 Rules for Living Your Dream" ... and gave his take on why he thinks there's recently been an increase in objects flung at performers.

Jason says the whole thing started with fans tossing their phones at the stage in hopes their favorite artist would snap a pic using the device. After a bunch of performers actually did start taking photos, it gave way to more phones being thrown ... with a mix of other random stuff.

Jason says it's up to performers to stop engaging with the items being thrown ... which will hopefully stop all the madness.

As we reported, Bebe Rexha got nailed in the face by a fan's phone at a show earlier this month, ending up with a black eye and some stitches. The fan was eventually charged for the stunt.

We've since seen Ava Max slapped by a fan while performing, and even Kelsea Ballerini took a bracelet to the face at a recent concert.

Charlie Puth even took to Twitter to share his thoughts on the recent incidents and said, "This trend of throwing things at performers while they are on stage must come to an end. (Bebe, Ava, AND NOW Kelsea Ballerini…) It's so disrespectful and very dangerous. Please just enjoy the music I beg of you…"