Originally NLP taught that most people had an internal preferred representational system (PRS) and preferred to process information primarily in one sensory modality. The practitioner could ascertain this from external cues such as the direction of eye movements, posture, breathing, voice tone and the use of sensory-based predicates.
If a person repeatedly used predicates such as “I can see a bright future for myself”, the words “see” and “bright” would be considered visual predicates. In contrast “I can feel that we will be comfortable” would be considered primarily kinesthetic because of the predicates “feel” and “comfortable”.
These verbal cues could also be coupled with posture changes, skin color or breathing shifts. The theory was that the practitioner by matching and working within the preferred representational system could achieve better communication with the client and hence swifter and more effective results.
Many trainings and standard works still teach PRS whilst other proponents have de-emphasized the existence and relevance of PRS and instead emphasize working within all representational systems. In particular, New Code emphasizes individual calibration and sensory acuity, precluding such a rigidly specified model as the one described above.
Responding directly to sensory experience requires an immediacy which respects the importance of context. Grinder has stated that a representational system diagnosis lasts about 30 seconds.
Although there is some research that supports the notion that eye movements can indicate visual and auditory (but not kinesthetic) components of thought in that moment, the existence of a preferred representational system ascertainable from external cues (an important part of original NLP theory) was discounted by research in the 1980s.