READING RATES 



505 



reading and tracking gave a lower total transmission rate. However, 

 Licklider and we agree on the magnitude of this maximum — between 

 40 and 45 bits/sec for facile test subjects. 



Measurements on combined reading and tracking rates were made in 

 Experiment 5 using words from the preferred lists. Whereas Licklider's 

 readers made a dot within a box next to the word read, our readers 

 placed a dot as close as possible to a vertical line next to the word read 

 (e.g. dog |-)- The computation of transmission rate is shown in Ap- 

 pendix II. The reading-while-tracking rates were 2.4, 2.0 and 1.4 words/ 

 sec. The computed information rates are given in Table III. 



It may be seen that the reading rate during tracking dropped so much 

 that the two channels together give a total information rate less than 

 those for reading the preferred list alone. Licklider's reading lists were 

 words chosen randomly from a dictionar}^ and are presumably not chosen 

 optimally for maximum information rate — his information rates for 

 reading alone were 30-35 bits/sec, as compared with the 32-43 bits/sec 

 found here for the scrambled prose and preferred lists. However, if we 

 assume that our reading-while-tracking rate, which is much slower than 

 the reading rate for scrambled prose or for the preferred lists, is limited 

 largely by tracking, we might have obtained a slightly higher informa- 

 tion rate in reading-while-tracking by using a larger list of words. This 

 is suggested by the fact that Licklider's and our experiments obtain 

 about the same reading- while-tracking speeds. 



