The fact that the maximal rates of syllable production closely match the optimal auding and reading rates should not be taken to necessarily imply the syllable as the "basic" unit of language. It may be, but there are many problems in adequately defining syllables (Shuy,1969) both as units of speech and as units of print. For present purposes, it is sufficient to note the similarities among rate of syllable production (movement of articulators), rapid auding, and rapid reading, and to point out the relevance of this observation to Hypothesis 3 and the developmental model.

Speculation on the Rate of Conceptualizing. Lenneberg (1967, p. 90) points out that, while most adults are capable of producing common phrases or clicheS at rates up to 500 syllables per minute, more frequently they speak at 210 or 220 syllables per minute (150 wpm). He then states: "Apparently, the most important factor limiting the rate of speech involves the cognitive aspects of language and not the physical ability to perform the articulatory movements. We may not be able to organize our thoughts fast enough to allow us to speak at the fastest possible rate."

It is likewise possible that in auding and reading we may not be able to merge the thoughts being presented with our own conceptual base fast enough to "track" the oral or printed message. Possibly it is primarily lack of conceptualizing time which causes the gradual loss in comprehension when auding and reading speech are increased up to 250-300 wpm. Beyond 300 wpm then, the loss in comprehension may reflect both lack of conceptualizing time and inability to mobilize inner articulatory patterns rapidly enough to faithfully follow the message.

Evidence that ability to rapidly conceptualize is related to ability to comprehend rapid rates of speech is available in a study by Friedman and Johnson (1969). They administered a group of cognitive tests to college students who also auded materials presented at 175, 250, 325, or 450 wpm. One of the cognitive tests-the Best Trend Name Test-requires students to infer the semantic relationships among a set of words. For example, the words "horse- pushcart-bicycle-car" are presented and the student is asked to decide whether the relationship among the four terms is best described as one of "speed", "time", or "size". The correct answer is "time" since the sequence describes an order of historical development, horses were the earliest means of transportation, cart the most recent.