Brief ReportRapid fast-mapping abilities in 2-year-olds
Introduction
The study of fast mapping focuses on what children learn about a word after minimal exposure to a new label (for reviews, see Jaswal and Markman, 2001, Wilkinson and Mazzitelli, 2003, Woodward and Markman, 1998). The term unambiguous or ostensive refers to a naming act in which external cues (e.g., overt linguistic cues, cues from communicative intent) that direct children’s attention to the correct referent are provided. Although behavioral cues carry with them their own challenges of ambiguity, experimenters have successfully elicited fast mapping by overtly drawing children’s attention to the referent via pointing (Baldwin, 1993a, Leung and Rheingold, 1981), eye gaze (Baldwin, 1991, Baldwin, 1993b, Dunham et al., 1993), or an explicit linguistic contrast (e.g., “Bring me the chromium tray, not the red one; I want the chromium one”) (Carey & Bartlett, 1978). In the most extreme case, the correct referent is the only object present, making the referent of the new word quite clear (Au and Glusman, 1990, Baldwin et al., 1996, Booth and Waxman, 2002, Dickinson, 1984, Markson and Bloom, 1997, Waxman and Booth, 2000).
Recent work has extended these demonstrations of fast mapping to more ambiguous labeling acts, showing that 2-year-olds can learn as much about a new word from an indirect exposure as from an act of ostensive labeling (Jaswal & Markman, 2001; for related results, see Golinkoff et al., 1992, Mervis and Bertrand, 1994, Rice, 1990, Vincent-Smith et al., 1974, Wilkinson and Mazzitelli, 2003). Work on fast mapping has also shown that children can retain a newly learned word for a significant amount of time following the initial encounter. In the original demonstration, Carey and Bartlett (1978) showed that children remember some semantic information about a novel label more than 1 week after a single encounter with it. Markson and Bloom (1997) extended this result and showed successful retention at delays of 1 month after the initial exposure to a single new word.
Although these studies have been integral to our understanding of fast mapping, many questions remain. For example, the connection between identifying the correct referent during learning (referent selection) and reidentifying it at test (referent retention) has received less attention. One recent contribution is a study by Horst and Samuelson (2008) in which 24-month-olds were exposed to eight novel object–label mappings during a referent selection task and retention for these mappings was tested after a 5-min delay. The authors found that although children succeeded during the initial referent selection trials, they failed to correctly reidentify the target during the delayed retention test trial. The difficulty of transitioning from referent selection to referent retention can be further complicated because children may hear multiple new words in quick succession. This challenge may be ameliorated with multiple exposures to a new word across trials (Mather & Plunkett, 2009) or multiple naming acts in a natural conversation.
In the most common experimental designs, children learn only a few object names or only one object name (Baldwin et al., 1996, Behrend et al., 2001, Dollaghan, 1985, Golinkoff et al., 1992), the novel label may be repeated many times (Au and Glusman, 1990, Markman et al., 2003, Woodward et al., 1994), and the object being referred to is clearly indicated (Carey and Bartlett, 1978, Markson and Bloom, 1997, Mervis et al., 1994). If children rely on fast mapping to rapidly acquire new words, then they must be able to demonstrate successful learning under a wide range of conditions. A manipulation that has yet to be tested in a single experiment is whether children can use fast mapping to learn multiple novel words when each object and label is presented only once under ambiguous and time-constrained conditions (but see Horst & Samuelson, 2008).
We had two goals for our experiment: (a) to test the fast-mapping abilities of 2-year-olds under conditions that are challenging on a number of dimensions and (b) to investigate whether such conditions allow children to succeed at both the initial mapping of a novel label to a novel object (referent selection) and the retention of this mapping for use at a later time (referent retention). We presented children with six ambiguous referent selection novel label trials over the course of the study. On these trials, children saw a familiar object (e.g., a ball) and a novel object, and a voice on a computer asked them to “point at the _____ [e.g., glark].” Including the four practice trials, children saw 38 familiar objects and 12 novel objects, they heard 22 familiar labels and 6 novel labels, and each label was uttered only once in an ambiguous context over the course of a 10-min experiment.1 We tested retention for the novel labels by presenting all six previously labeled novel objects and probing retention for one of them in a single posttest retention trial.
Section snippets
Participants
Participants were 72 English-speaking 24- to 36-month-olds (38 boys and 34 girls, mean age = 30.08 months, SD = 3.25). An additional 28 children participated but were removed from the sample for parental interference (n = 6), refusal to point (n = 7), fussiness (n = 3), failure to complete training (n = 7), or experimenter/equipment error (n = 5). Participants were randomly placed in one of six conditions controlling for trial order and side of image presentation.
Procedure
Participants were seated in a
Results
Pointing during referent selection was coded from videotape by observers who were blind to which screen depicted the target object. Coders scored each child’s first point after label onset to either the target screen or the distracter screen. Preliminary analyses suggested no differences between the two types of known label trials (i.e., known distracter and novel distracter), and so these were combined as known label trials throughout analyses.
Discussion
In the current study, we asked whether 2-year-olds can learn novel nouns from a single ambiguous exposure that lasts only 3 s. Our results demonstrate that despite the challenging conditions under which learning and testing took place (in terms of the large number of objects presented, the limited exposure to each object, and the lack of any reinforcement), a significant portion of the children in our sample were able to learn and retain at least one of the novel words they encountered during
Acknowledgments
The authors thank Amelia Hritz, Miyuki Nishimura, and Xin Yuen for help in data collection and coding and also thank Amy Stocker for help in editing the manuscript.
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2021, CognitionCitation Excerpt :We chose this explicit measure because it is the one used in much research on the mutual exclusivity constraint. Studies that have tested 2-year-olds on similar tasks have shown that, even though children correctly map the novel word cheem to the unfamiliar object on the fly, they often fail to retain the mapping established via mutual exclusivity in memory when tested at short (i.e., on the order of 5–10 min) retention intervals (e.g., Horst & Samuelson, 2008; see Samuelson & McMurray, 2017 for review; but cf. Spiegel & Halberda, 2011). While this means we were expecting the youngest children to perform well below ceiling overall in our explicit memory test, it also provides an additional motivation for our study: If children initially encode novel words only weakly in memory after a first encounter, is it possible to strengthen such memory traces by encouraging them to generate linguistic expectations that will be later disconfirmed?