Figure 6. The figure shows younger adults performance as a function of older adults' performance for event cued (EC) prospective memory proper, EC vigilance and time cued (TC) vigilance tested in the laboratory, and for TC prospective memory proper and TC habitual prospective memory tested in natural settings.

The figure also includes the best fitting estimated d derived by double variate square error minimization methods and bootstrap 95% confidence intervals. The figure highlights that the majority of all contrasts reveal age-related declines in ProM measured in the laboratory and that such age declines depend on ProM subdomain–they are largest for EC prospective memory proper (the best fitting d = −1.13) and smallest for EC vigilance (the best fitting d = −.77). In contrast, the majority of all age contrasts showed substantial age improvements in natural settings (the best fitting d = 0.53 for TC prospective memory proper and 0.76 for TC habitual prospective memory). Importantly, the figure highlights that the size of raw age-related differences in individual studies is determined by the degree of ceiling effects, that is, the distance of the lower scoring group from the maximum achievable score. The bottom right panel summarizes the findings; it depicts a summary graph of the average effect sizes by ProM subdomain, cue type, and task type. It highlights that under controlled laboratory conditions all subdomains of ProM for which sufficient data exist show substantial age-related declines, and more importantly, that such age declines are much larger for EC prospective memory proper (d = −1.13) than for EC vigilance (d = −0.77). In contrast, under naturalistic conditions, older adults perform better than younger adults on ProM tasks that have been investigated: TC prospective memory proper (0.53) and TC habitual prospective memory (0.76).