Comprehension of Connected Meaningful Discourse as a Function of Rate and Mode of Presentation

THERE HAVE been a number of investigaj tions in the past few years designed to investigate the effects of varying the speed of presentation of meaningful material upon listener compre hension. There have also been studies which have investigated the differences between the auditory, visual, or audiovisual modes of presentation. There have, however, been few studies which have investigated the interrelationships between the speed and the mode of presentation. Goldstein (2) presented connected meaningful material at several rates ranging from 100 to 322 words per minute (wpm) both auditorally and visually. He found an almost linear loss in comprehension as the speed was increased. He also found that for his subjects who ranged in age from 18 to 65 years the auditory presentation resulted in higher levels of comprehension than the visual presenta tion at the lower speeds but that as the speed was increased, comprehension by the visual mode of presentation gradually became equal to that of the auditory presentation. Goldstein varied the rate of presentation by training an expert speaker to deliver the ma terial at the various rates used in the study. This j material was recorded and minor adjustments in speed were made by varying the playback speed of the recordings. Although Goldstein claimed a high level of intelligibility of the auditory ma terial, there is a possibility that some loss of in telligibility resulted from the speaker's increased rate. Goldstein presented the visual material with motion picture equipment. The rate of presenta tion could be very accurately controlled so that it matched exactly the rate of the auditory pres entation. Goldstein's conclusion that there seemed to be no "optimum rate" at which the ma terial should be presented was based upon a rather straightforward interpretation of the linear rela tionship between the rate of presentation and comprehension. If some sort of efficiency index had been calculated, an optimum level might have been determined, but this cannot be computed from the data given. Fairbanks, Guttman, and Miron (4) did compute an efficiency index based upon the number of comprehension test items answered correctly per unit time. Their study, however, was concerned only with the auditory mode of presentation. The optimum rate for the auditory presentation was reported as about 280 wpm. This rate was twice as fast as the original recording and is considerably faster than every day speech. In a later study by Fairbanks, Gutt man and Miron (5) subjects were presented with the material twice instead of just once. The re sults clearly indicate that the double presenta tion at the rate of 282 wpm results in higher comprehension scores than a single presentation at the slower rate of 141 wpm (p