(Bloomberg) – U.S. teenagers are more reckless after theirfirst few years of driving, often becoming overconfident in theirabilities and putting themselves at higher risk for accidents, anew study shows.

More than half of high school seniors have car accidents or nearmisses, compared with 34% of sophomores, according to the studyconducted by Liberty MutualInsurance Co. and the group Students AgainstDestructive Decisions (SADD).

Related: 5 driving risks you need to talk about with yourteens

Misplaced confidence

More people, including “hyper-connected” teenagers, aredistracted by their phones while driving, and insurers are seekingto counter reckless behaviors amid an increase in car accidents inrecent years.

According to the study, 75% of high school seniors “feelconfident” in their driving abilities, and 71% use a phone behindthe wheel. The study said the misplaced confidence could stem fromparents who taper off punishment for poor driving after their kidshave a year or two of practice under their belts.

Related: 10 safe and affordable cars for teendrivers

“Older teens are still inexperienced drivers — even if theyfeel otherwise,” Mike Sample, lead driving-safety consultant atLiberty Mutual, said in the report. “Using an app behind the wheel,even glancing away for a second, can impair your driving abilityand set off a chain reaction that could lead to a near miss orcrash.”

Phones aren't the only issue. Driving while drowsy, speeding,having multiple passengers and browsing music become more prevalentas new drivers gain confidence.

Driving behavior

Changing music via phone or app

• 26% Sophomores
• 32% Juniors
• 40% Seniors

Having 3+ passengers

• 31% Sophomores
• 35% Juniors
• 47% Seniors

Speeding

• 18% Sophomores
• 23% Juniors
• 35% Seniors

Driving when drowsy

• 13% Sophomores
• 15% Juniors
• 26% Seniors

Sam Bessette, a 16-year-old from Topeka, Kansas, said she sticksher phone in the cupholder of her 2009 Ford Escape while shedrives.

“My mom is very against it,” Bessette said of distracteddriving, “despite the fact she uses her phone all the time. But shetells me she'll take my car.”

Related: 7 back-to-school driving safetytips

Bessette said she's a “fairly good” driver, and her friendstrust her behind the wheel. She was in a fender bender once, whenthe driver in front of her slammed on his brakes. She said she'djust barely glanced away to change the radio station and didn'thave enough time to react.

Teens naturally gains confidence as they drive more

Dr. Gene Beresin, a senior adviser onadolescent psychiatry at SADD, said teens naturally gain confidenceas they drive more.

“As a result, it is even more important for parents and teens tohave conversations about safe driving practices to avoidpotentially putting themselves and others at risk on the road,”Beresin said in the report.

Related: 10 states with the highest cost of adding a teen toan auto policy

Liberty Mutual, the third-largest U.S. property-casualtyinsurer, surveyed almost 3,000 teens from high schools across thecountry and 1,000 parents of young drivers for the study.

The insurer encourages parents to continue teaching their kids,even after they get licenses. Also, adults can use tracking devicesthat monitor driver habits and reward teens for safety behind thewheel, the Boston-based company said.

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