@candyquilt-- Learning theories like behaviorism are different methods used to analyse learning and development. So it's not really about how people learn but rather how to track human learning.
An infant's development and learning can be explained using one or more learning theories. If behaviorism is used, then only the behavior of the child will be considered to analyse development.
Behaviorism and cognitivism are competitive in the sense that psychologists usually prefer to use one theory/method rather than the other.