cortex activity than younger adults while engaging in emotion-processing tasks, we argue that the cognitive control hypothesis is a more likely explanation for older adults' positivity effect than the aging-brain model. Copyright © 2011 S. Karger AG, Basel In contrast with the age-related declines in many domains of cognitive functioning [1] , emotion regulation functioning improves somewhat with age [2] . People experience less negative affect as they get older and can restore their good mood after being induced into a negative mood more effectively than younger adults [3] . Older adults also show a 'positivity effect' in attention and memory [4] . For instance, older adults sometimes spend a larger proportion of time viewing positive items and a smaller proportion viewing negative items than do younger adults [5,6] . Moreover, in some studies, compared with younger adults, less of what older adults remember is negative and more is positive [5,7,8] . Such age by valence interactions tend to have a medium effect size [8] ; thus, as might be expected, studies with relatively small participant groups do not always reveal significant age differences. Other factors, such as a level of arousal of stimuli [9] , availability of cognitive resources [6] or types of measurements across studies [10] , may also account for the presence or absence of a positivity effect.Why do older adults show some improvements in emotion regulation despite suffering age-related cogni-
Key WordsEmotion ؒ Aging ؒ Functional magnetic resonance imaging ؒ Positivity effect ؒ Amygdala ؒ Prefrontal cortex Abstract Despite the fact that physical health and cognitive abilities decline with aging, the ability to regulate emotion remains stable and in some aspects improves across the adult life span. Older adults also show a positivity effect in their attention and memory, with diminished processing of negative stimuli relative to positive stimuli compared with younger adults. The current paper reviews functional magnetic resonance imaging studies investigating age-related differences in emotional processing and discusses how this evidence relates to two opposing theoretical accounts of older adults' positivity effect. The aging-brain model [Cacioppo et al. in: Social Neuroscience: Toward Understanding the Underpinnings of the Social Mind. New York, Oxford University Press, 2011] proposes that older adults' positivity effect is a consequence of age-related decline in the amygdala, whereas the cognitive control hypothesis [Kryla-Lighthall and Mather in: Handbook of Theories of Aging, ed 2. New York, Springer, 2009; Mather and Carstensen: Trends Cogn Sci 2005; 9: 496-502; Mather and Knight: Psychol Aging 2005; 20: 554-570] argues that the positivity effect is a result of older adults' greater focus on regulating emotion. Based on evidence for structural and functional preservation of the amygdala in older adults and findings that older adults show greater prefrontal