Labeling objects during categorization tasks has been repeatedly shown to help infants categorize 
objects by highlighting their commonalities. Although much work supports this label-as
category-marker hypothesis, other findings support a label-as-feature hypothesis. According to 
this view, labels start as object features, and only become category markers later in childhood. 
Developing in parallel, infants appear to rely on specific word learning principles based on their 
linguistic experience. That is, monolingual infants have been repeatedly shown to use a 
disambiguation heuristic to map novel words to novel objects. The aim of the current study was 
therefore to examine how monolingual infants categorize objects in an interactive categorization 
task when presented with one or two labels. Based on previous work, we hypothesized that 18
month-old monolinguals would perform significantly worse when objects were given two labels, 
than when they were given a single label. We also administered a mutual exclusivity task to 
examine if toddlers’ expectation of a one-to-one mapping between words and object kinds is 
related to their performance on the categorization task. Unexpectedly, toddlers’ categorization 
was enhanced both when objects were given one or two labels. We discuss these findings and 
suggest that future work should examine the manner in which monolingual infants process a 
second novel label during category formation, and if it relates to their ability for disambiguation, 
through the use of eye-tracking.