motivation human 204 Humans 162 Motivation 139 male 129 female 127 adult 119 Female 79 article 75 Male 72 Article 68 controlled study 67 Adult 62 psychology 51 young adult 51 human experiment 47 Young Adult 42 adolescent 42 major clinical study 42 Adolescent 40 physiology 37 reward 34 middle aged 31 questionnaire 30 Middle Aged 28 Goals 26 Reward 26 decision making 24 clinical article 23 aged 21