article human female 141 male 134 Humans 126 adult 117 controlled study 87 Female 82 Male 81 human experiment 77 major clinical study 73 Adult 56 adolescent 50 child 48 Adolescent 42 young adult 39 Young Adult 38 Middle Aged 35 psychology 35 Child 34 middle aged 32 groups by age 30 aged 29 ethnic group 29 clinical article 28 lowest income group 24 Aged 20 peer group 20 questionnaire 20 perception 19