“…In contrast, in reaching versions of the tasks eighteen-month-old toddlers do not perform well on reference selection or retention (Kucker, McMurry & Samuelson, 2018), 24-month-olds perform well on reference selection, but they do not retain the mappings (Samuelson & Horst, 2008), and by 30 months of age children are good at both (see Kucker, McMurray, & Samuelson, 2015a for a review and discussion). Both reference selection and retention, however, can be influenced by a number of external and organismic factors (see e.g., Axelsson & Horst, 2014;Kalashnikova, Escudero & Kidd, 2018;Kucker & Samuelson, 2012;Pomper & Saffran, 2018, Twomey, Ranson, & Horst, 2013. Still other research indicates that children as young as 13 months of age can map and, in some cases, retain novel word-object mappings when only one name and one object are presented at a time (Schafer & Plunkett, 1998;Woodward, Markman, & Fitzsimmons, 1994).…”