Some reading research has indicated that instructing a group or class of readers to speed up their reading rate will increase reading comprehension to a limited degree. In fact, inexperienced readers will often choose a rate slower than is appropriate for the material being read. However, this is only true to up to a point. When reading rate is increased to beyond the reading for comprehension rate (over approximately 400wpm), comprehension will drop to an unacceptable level (below 50% comprehension) as measured on standardized reading tests.
Empirical research on reading rate indicates that reading for comprehension is best achieved at 200-350 words per minute. This has been found to be constant for all competent readers. Research conducted on rapid reading courses indicates that they are actually teaching a limited kind of skimming. Skimming can be learned easily without the need for an expensive course, and involves reading at a rapid rate for the purpose of searching rather than comprehension. As a habitual reading rate, it is inappropriate for sufficiently comprehending newspaper articles, textbooks, and novels.
Research on sub vocalization., or auding, shows that it is a natural process which helps comprehension, and can be encouraged, especially for the purpose of reading high quality prose. Sub vocalizing will only decrease reading rate if it is accompanied by obviously visible movements of the mouth, jaw or throat.
Research conducted on speed reading experts who claim to be able to read at over 1,000 words per minute with full comprehension has found that their claims are false. Even speed reading rates of between 1000-2000 wpm have been found to result in comprehension levels at around 50% or lower. Also, when presented with two paragraphs of combined but unrelated material, speed reading experts claimed that they understood it but were completely unaware that it consisted of two obviously different passages mixed together.
One interesting outcome from research into speed reading is that speed readers tend to poorly assess their own comprehension level when compared to normal readers who are simply instructed to skim a text. The skimming group was found to be better at extracting the details out of a text than speed readers. This may be explained with reference to speed reading practices training out the ability to judge comprehension and leading the reader to adopt misconceptions about reading.
Professional reading rate researchers' general advice about speed reading courses is simply not to enroll. Skimming can be learned easily without the need for expensive courses, and comprehensive study techniques can be learned for free or for a small fee at community colleges. Indeed, great results can be obtained using reading rates appropriate to the material, a wide repertoire of learning strategies, and an accurate judgment of reading comprehension.