“…Additionally, their visual search is altered (Maltz & Shinar, 1999), older drivers make more mistakes in estimating the speed of other vehicles (Scialfa, Guzy, Leibowitz, Garvey, & Tyrrell, 1991), they take longer to switch tasks (Kray & Lindenberger, 2000), and solve novel problems worse (Baltes, Staudinger, & Lindenberger, 1999). However, although every aging individual is affected by this decline, its speed and intensity vary strongly between them (Hultsch, MacDonald, & Dixon, 2002) and this variability, in addition, increases with age (Morse, 1993). Hertzog et al (2008) describe the decline as a "zone of possible functioning" (p. 1) whose borders are set by person-specific endowments and age-related constraints.…”