There has been a surge in interest in the benefits of bilingualism against age-related cognitive decline. Klein & Viswanathan found that the normal decrease in attention control observed in older adults was reduced in bilinguals, suggesting that bilingualism may be protective against the effects of cognitive aging. Elderly bilinguals have also been shown to be better at switching between tasks, ignoring irrelevant information and resolving conflicting cognitive alternatives. Bilingualism may be one of the environmental factors which contributes to 'cognitive reserve'. Cognitive reserve is the idea that engagement in stimulating physical or mental activity can act to maintain cognitive functioning in healthy aging and postpone the onset of symptoms in those suffering from dementia. Factors that contribute to this also include education, occupational status, higher socioeconomic class, and the continuing involvement in physical, intellectual and social activities.