Aging and numerosity estimation

In two experiments, young and older participants were asked to find the approximate number of dots in collections including between 40 and 460 dots. Experiment 1 showed that both age groups had comparable performance and no age-related differences in the power-function exponents for numerosity. Experiment 2 found that these age-related similarities were not due to speed–accuracy trade-offs or to compensation by older adults for potential age-related decline in numerosity estimation processes. Furthermore, young and older participants’ estimation performance was influenced by physical features of stimuli only for very large numerosities, presumably because these are poorly represented in long-term memory. Implications of these findings for the further understanding of how participants accomplish numerosity estimation tasks and effects of aging in this domain are discussed. H OW do we estimate numerosities of large sets of items?The present two experiments document numerosity esti-mation (i.e., finding the approximate number of elements in sets of items) in young and older adults. In them, we attempt to determine whether estimation performance is influenced by physical features (e.g., size of items or filled area of items) for all numerosities, as suggested by many previous results