Often the primary response may be a case of metonymical extension. A child who has always seen an orange at the breakfast table may have a tendency to say “orange” one morning when there are no oranges present because all of the other features that accompanied the orange in the past are present.
A verbal relationship with the following features:
A non-verbal stimulus
The non-verbal stimulus is some aspect of a primary verbal relationship
The specific features of the controlling relationship (e.g., receptor being stimulated or the intensity or strength of the stimulation; stimulation may include an establishing response)
The form of the response