than by another. For example, within education, spelling is better learned by children who have unconsciously used a strategy of visualization, than an unconscious strategy of phonetically "sounding out". When taught to visualize, previously poor spellers can indeed be taught to improve. NLP proponents also found that pacing and leading the various cues tended to build rapport, and allowed people to communicate more effectively. Certain studies suggest that using similar representational systems to another person can help build rapport whilst other studies have found that merely mimicking or doing so in isolation is perceived negatively. Skinner and Stephens (2003) explored the use of the model of representational systems in television marketing and communications. Some exercises in NLP training involve learning how to observe and respond to the various cues in real time. The preferred representational system (PRS) Originally NLP taught that people preferred one representational system over another. People could be stuck by thinking about a problem in their "preferred representational system" (PRS). Some took this idea further and categorised people as auditory, kinesthetic, and visual thinkers (see also: learning styles). It was claimed that swifter and more effective results could be achieved by matching this preferred system. Although there is some research that supports the notion that eye movement 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. Some still believe the PRS model to be important for enhancing rapport and influence. Others have de-emphasized its relevance and instead emphasize that people constantly use 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. John Grinder has stated that a representational system diagnosis lasts about 30 seconds. In a review of research findings, Sharpley (1987) found little support for individuals to have a "preferred" representational system (PRS), whether in the choice of words or direction of eye movement, and the concept of a preferred representation system (PRS). Similarly, The National Research Committee found little support for the influence of PRS as presented in early descriptions of NLP, Frogs into Princes (1979) and Structure of Magic (1975). However, "at a meeting with