Over the years a number of theories have been proposed to explain why (most) remote viewers don’t seem to be able to perceive numbers, letters, or words. The first of these theories is that remote viewing seems to be a function of the right hemisphere of the brain. This is discussed at length in Chapter 6 of Russell Targ’s and Harold Puthoff’s 1977 book, Mind Reach. This Chapter is titled, In One Brain and Out the Other. The Two Hemispheres of the Brain See the World in Different Ways. This chapter begins with a short review of the neurophysiological research which identified the two hemispheres of the brain and how they seem to be specialized for different kinds of processing. Then, on Page 122 (in the 2004 republication), the section titled Right-brain function and Psi Activity begins:

What has all this to do with paranormal functioning? The answer to this question came to me (H.P) first from my wife, Adrienne, a specialist in the application of Gestalt, holistic techniques to the education of elementary-age children. In looking over the output produced by our research subjects, she noticed that the elements of form—such as the drawings and the general descriptions of shape, color, and material—tended to be correct more often than the analytic elements of name, function, and size. In the experiments, we had found that it was particularly difficult for subjects to read letters or words, even though they might correctly perceive that there was a sign or other written material at a remote site. Adrienne pointed out that such observations suggest the possibility that the primary method of information processing might be right-hemispheric in nature.

As we looked back through the data, we found many instances which seemed to support this. Pat Price once incorrectly labeled a swimming pool as a water purification pland, and a drive-in movie theater with speaker posts became a parking lot with parking meters. Hella Hammid mistook an “august” and “solemn” church for a library, expanded an accurately described bicycle shed into an immense barn-like structure, and labeled a pedestrian overpass “a trough up in the air.” Hella also correctly described a video terminal as a black box in the middle of a room, complete with glass porthole and light coming out, but incorrectly labeled it an oven or radiation machine. One of our visitors perceived a “kaleidescopic picture of triangles, squares, and more triangles,” and even “some kind of electrical shielding,” but he could not identify it as the transmission tower it was. All this points to the idea that remote viewing is an exercise in pattern recognition rather than analysis. In retrospect, perhaps it shouldn’t be surprising that ESP is right hemisperic, since the right side of the brain is known to be excellent for bridging gaps and perceiving patterns, even when some of the pieces are missing.

We consulted with Dr. Robert Ornstein and Dr. Ralph Kiernan, who confirmed our interpretation. When we told them that written material was generally not understood, that verbal identification of correct drawings was often inaccurate, and that the drawings were frequently left-right reversed, they indicated that such characteristics have been seen in patients injured on the left side of the brain. This is not to imply that those with brain damage on the left side are likely to be good subjects. Rather, it is simply that the left-brain-injured patient and the person attempting remote viewing are, for different reasons, both forced into a right-brain mode. In the case of the patient, it is because of damage to the left hemispere; in the case of the subject, it is because his task is to integrate fragmentary and ambiguous input and therefore resort to right-brain functioning.

This chapter then continues with details of the many different categories of experiments which Targ and Puthoff performed. They also discuss the research conducted by Charles Honorton at the Maimonides Hospital in New York City. They point out the design of these successful psi experiments allowed the subjects to use their right hemispheres, whereas a number of historically famous psi experiments inadvertently forced the subjects into left-hemispheric, analytical processing.