A study assessed the effects of playing a computer game (solitaire) during lunch on snack behavior. A sample of 44 healthy adults was randomly assigned to eat lunch either with the computer game distraction or without distraction. All participants ate the same breakfast and lunch. Thirty minutes after lunch, participants were offered cookies as a snack and were instructed to eat as many or as few cookies as they liked. Those who ate with the distraction ate on average 52 grams of cookies, compared with 27 grams for those who ate without the distraction -- a surprisingly substantial difference. Carefully and methodically examine the information provided. What type of study is this