Words: what are they, and do animals have them?

Area of Science:

• Cognitive Science
• Comparative Psychology
• Linguistics

Background:

• The function of words in categorization is not fully understood.
• Young children initially favor thematic associations over taxonomic ones.
• Nonsense words can influence children's categorization, shifting them towards taxonomic choices.

Purpose of the Study:

• To investigate whether young, language-trained chimpanzees exhibit a similar thematic-taxonomic shift as human children.
• To explore the early stages of word learning and categorization in a non-human primate model.
• To critically evaluate the interpretation that this shift demonstrates an innate understanding of words as category names.

Main Methods:

• Adapted the Markman and Hutchinson (1984) procedure for use with chimpanzees.
• Trained chimpanzees on simple word-use functions ('X goes with Y', 'if shown X, get Y').
• Assessed categorization shifts when novel words (nonsense labels) were introduced.

Main Results:

• Language-trained chimpanzees demonstrated a thematic-taxonomic shift, mirroring the behavior of young children.
• This shift occurred despite the chimpanzees' limited word-training functions.
• The results suggest that the shift effect may not solely rely on an explicit understanding of words as category names.

Conclusions:

• The thematic-taxonomic shift can be observed in non-human primates, suggesting a potential evolutionary basis for this learning mechanism.
• The findings challenge the strong interpretation that this shift inherently proves knowledge of words as category names.
• Further research is needed to understand the nature of word meaning, potentially integrating information retrieval and intentionality frameworks.