  Developmental psychologists have spent decades devising experiments to test
the intelligence and knowledge of infants and children, tracing the origin of
crucial concepts and capacities. Moreover, experimental techniques in
developmental psychology have been carefully designed to discriminate the
cognitive capacities that underlie particular behaviors. We propose that using
classical experiments from child development is a particularly effective way to
probe the computational abilities of AI models, in general, and LLMs in
particular. First, the methodological techniques of developmental psychology,
such as the use of novel stimuli to control for past experience or control
conditions to determine whether children are using simple associations, can be
equally helpful for assessing the capacities of LLMs. In parallel, testing LLMs
in this way can tell us whether the information that is encoded in text is
sufficient to enable particular responses, or whether those responses depend on
other kinds of information, such as information from exploration of the
physical world. In this work we adapt classical developmental experiments to
evaluate the capabilities of LaMDA, a large language model from Google. We
propose a novel LLM Response Score (LRS) metric which can be used to evaluate
other language models, such as GPT. We find that LaMDA generates appropriate
responses that are similar to those of children in experiments involving social
understanding, perhaps providing evidence that knowledge of these domains is
discovered through language. On the other hand, LaMDA's responses in early
object and action understanding, theory of mind, and especially causal
reasoning tasks are very different from those of young children, perhaps
showing that these domains require more real-world, self-initiated exploration
and cannot simply be learned from patterns in language input.
