The existence of formal similarity, even minimally, allows for a unique form of self-reinforcement. This can make the acquisition and maintenance of responses that produce formal similarity between their products and their controlling stimuli more likely to occur, allowing for a form of self-correction. In the case of verbal behavior, the two general categories in which this can occur are when we repeat what has just been said, or when we copy what someone has written. This same type of self-correction is possible in any type of vocal mimicry and/or type of copying.
A relationship between a stimulus that evokes a response and the response-product of that response with the following features:
The stimulus and the response-product are both in the same modality (e.g., they are both visual or they are both auditory)
Their physical patterns or sequences resemble one another (e.g., they may look or sound alike)
Specific formal or dynamic features of the stimulus and the response-product
The number of additional formal or dynamic features resembling one another