UCLA

Not all categories are made the same. Some categories have high within-category variability (e.g., “vehicles” can look very different) and some have low within-category variability (e.g., “cats” are pretty similar). Categories can also vary on their between-category variability where some categories are very similar to each other (e.g., “cats” and “dogs”) and some are very different (e.g., “cats” and “vehicles”). Prior work has found that categories with high within and between variability are learned best in massed formats, and categories with low within and between variability are learned best in interleaved formats (Carvalho & Goldstone, 2014; Zulkiply & Burt, 2013). However, the unique contributions of each of these kinds of variability (i.e., within and between) have not previously been studied independently. Two studies (N=128) investigated the unique contribution of within- and between-category variability to 2-year-old children’s word learning in interleaved and massed presentations. These studies were conducted in a remote format through slide sharing in a video chat application. The first study investigated the impact of varying levels of between-category variability on word learning through massing and interleaving. This study found that higher between-category variability, compared to lower, led to higher performance at test (F(1,60)=13.51, p=.001, η_p^2=.184). These results show that being able to differentiate between categories is an important step in word learning. The second study investigated the impact of within-category variability. This study found no significant difference between high and low within-category variability (F(1,60)=2.89, p=.099, η_p^2=.045). In addition, neither study found significant differences between massed and interleaved conditions (Study 1: F(1,60)=0.64, p=.427, η_p^2=.011; Study 2: F(1,60)=0.05, p=.828, η_p^2=.001). These results suggest that different factors in the learning environment may impact how – and whether – children are able to learn new words in this online format. In sum, these two studies identify how between- and within-category variability impact word learning independently from each other at a stage in life where children are still developing their word learning capacities.