2.1.4. Reinforcing value of food task On the second and third visits, participants had the reinforcing value of food measured. Participants were asked to refrain from eating and drinking anything other than water for 3 h prior to their laboratory visit. Upon arrival, participants consumed a preload of 140 kcal (Nature Valley Yogurt Bar) in order to standardize pre-experimental food intake and to reduce variability that may come from different levels of hunger, as hunger is known to increase the reinforcing value of food. After this time, they completed a same-day and previous day dietary recall. They then completed a computer task to earn access to portions of the food selected based on their liking ratings during the phone screen.. Briefly, there were two computers with the same task on each. On the computer screen were three shapes with different colors. When the participant clicked the mouse button, the shapes would change color and orientation. When all of the shapes matched, the participant would earn one point. After five points, the participant earned a portion of food or reading time (depending upon which computer they were using). One computer was used to earn points toward food (100 kcal portions), the other was used to earn points toward time to spend reading Time or Newsweek magazine (2 min). Both tasks were on a progressive ratio schedule of reinforcement requiring 5 points to be earned for every reward, such that the first portion of food was earned after 20 mouse clicks, but the next one required 40 mouse clicks. The game ended when the subject no longer wished to earn points for food or reading. On one visit, the participant was required to consume the food or use the reading time as it was earned. On the other visit, the participants had to save up their food or reading time and use it at the end of the session once they no longer wish to earn points for food or reading time any more. The order of these sessions was counter balanced. In the interest of comparing across studies, the data from the visit where participants consumed the food as it was earned were not analyzed in this manuscript. At the end of the final visit, participants completed eating behavior questionnaires and had height and weight measurements taken. Participants were then debriefed about the purpose of the study and payment was provided. *ผลการทดลองของการทดลองที่ 1 คือ