tion respects children’s developing maturity and emerging autonomy. This is consistent with the moral purpose of assent.

Younger and Older Adolescents Consistent with a continuing maturation of cognitive capacities, most research shows differences between younger and older adolescents in their comprehension of providing informed consent to participate in research. Research on differences between adolescents and adults is more mixed.

A 1981 study by Lewis (involving 108 adolescents in the 7th, 8th, 10th, and 12th grades) looked at adolescents’ recognition of risks and future consequences in a hypothetical situation involving peer counseling about cosmetic surgery or a trial of acne medication. She found sizeable differences by age, with the older adolescents showing greater awareness of risk and future consequences. Older adolescents were also more likely to suggest the need for independent professional opinion about the situations presented to them. When Halpern-Felsher and Cauffman (2001) replicated the study, however, they did not find important differences by age in the ability to recognize of risks and future consequences. Their findings are consistent with the findings of studies by Kaser-Boyd and colleagues (1985) and Ambuel and Rappaport (1992).

In their study of competency to consent to medical treatment, which involved 98 participants at ages 9, 14, 18, and 21 years, Weithorn and Campbell (1982, p. 1589) reported that the 14-year-olds in their study did not differ from adults on four standards of competency: understanding, choice, reasoned outcome, and rational reasons. A number of summaries of the literature also suggest that by the age of 14 years, most adolescents possess the “psychological elements of ‘intelligent’ consent” (Grisso and Vierling, 1978, p. 420; see also Weithorn and Campbell, 1982; Leiken, 1993; Weir and Peters, 1997; Thompson, 2000b).

Others are more cautious about the capacity of adolescents to evaluate participation in research. For example, after reviewing the few studies of age-related differences in judgments of risk, Millstein and Halpern-Felsher (2001) state that, depending on one’s perspective, these studies could point either to a “heightened sense of vulnerability [among young people] compared to that among adults” or to a picture of adolescents being less accurate in their judgments than adults (p. 30). After noting the limitations of the available research (e.g., a lack of longitudinal studies that differentiate cohort from developmental influences), they conclude that “the finding of age-related increases in risk identification does call into question the degree to which we should consider adolescents, particularly younger adolescents, competent” (p. 24). Based on their review of the literature on the development of judgmental maturity, Steinberg and Cauffman (1996) concluded

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