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

Abstract

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 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 of presenta tion could be very accurately controlled so that it matched exactly the of the auditory pres entation. Goldstein's conclusion that there seemed to be no rate at which the ma terial should be presented was based upon a rather straightforward interpretation of the linear rela tionship between the 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 for the auditory presentation was reported as about 280 wpm. This 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 of 282 wpm results in higher comprehension scores than a single presentation at the slower of 141 wpm (p <.001, N=36). In terms of amount learned in a given amount of time, it is clear that the higher speed is more ef ficient than the lower speed. The method for speeding the material which Fairbanks, et al., used was developed by Fair banks, Everritt and Jaeger (3) and the method is termed speech compression. The compression is accomplished by discarding, periodically, small segments of the material to be compressed. The length of the segments is so small that no com plete phoneme is cut and the loss of a single seg ment is not detectable by the human ear. The re sult is material presented at a faster than the original with the speed dependent upon the size and frequency with which the segments are dis carded. Although the optimum of presenta | tion reported by Fairbanks, et al., (4) is about I 280 wpm, it appears possible for comprehension to take place at a speed of 470 wpm. Although the comprehension at such a high speed is small, it is provocative to ponder how much effect practice might have. The present study utilizes the technique of speeding the presentation of the auditory ma terial used by Fairbanks, et al., rather than that used by Goldstein. It also includes the condition I of audiovisual presentation as well as auditory