young child sitting at a table waiting patiently for a marshmallow

chair child control delay delayed desire development discounting experiment fast food goal gratification grit grow hurry immediate impulsive impulsivity indulgence large later learn longterm looking marshmallow now patience patiently performance perservere plate postpone preschool psychology punishment reinforcement resilience reward selfcontrol sitting small snack study sugar sweets table test toddler treat value wait waiting want watch young