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This eBook from the Gutenberg Project consists of approximately 678 pages of information about Harvard Psychological Studies, Volume 1.
Average             Average of   Average   Average   Mean Var
Frog.   of all.   Mean Var.     Sets.     of 1st h.  of 2d h.  of Sets.
1     227.3*     33.7*     229.4*      209.1*     249.6*    25.5*
225.2       207.3      243.0     42.1
2     240.1      30.9      239.0       222.3      255.1     29.0
241.3       220.2      262.4     32.8
4     270.3      56.5      298.5       285.3      311.4     62.8
242.2       206.0      278.4     50.2
198.5      26.2      195.0       197.5      193.0     33.5
202.0       195.2      209.0     18.8
6     224.4      24.4      221.6       209.7      233.7     23.6
227.2       213.5      241.0     25.1
Gen. Av. 231.5     34.3      231.0       216.6      246.6     34.3

For No. 5 the averages are for two sets of 18 each; for all the
others there are 24 in each set.

Transcriber’s Note:  All values in [sigma], 1/1000ths of a second.

TABLE XIII.

ELECTRICAL STIMULUS REACTION TIME.  SERIES 3.

Average             Average  Average    Average   Mean Var. 
Frog.     of all.   Mean Var.  of all.  of 1st h.  of 2d h.  of Sets.
1          93.6*   13.5*       91.8*    93.2*      90.4*     13.5*
95.4     91.8       99.0      13.5
2          99.9    12.8        92.2     89.4       95.0      17.4
107.5    105.9      109.0       8.2
4         125.2    16.3       113.5    106.5      120.5      13.6
136.0    135.7      138.2      19.0
5          94.4     8.0        88.6     90.5       88.6       8.2
100.2     97.8      102.7       7.9
6         102.5    12.2       104.2     98.6      109.9      12.8
100.9    101.0      108.3      11.6
Gen. Avs. 103.1    12.5       103.1    101.0      105.9      12.5

For each animal there are two sets of 24 reactions each.

  Transcriber’s Note:  All values in [sigma], 1/1000ths of a second.

The spinal reflex for a decapitated frog, as results previously discussed show, is approximately 50[sigma]; and every time the four-cell stimulus is given this kind of a reaction results.  There is a slight twitch of the legs, immediately after which the animal jumps.  Now for all these series the thread was slackened by one eighth of an inch, but the reflex time was determined without this slack.  Calculation of the lengthening of the reaction time due to the slack indicated it to be between 20 and 30[sigma], so if allowance be made in case of the reactions to the four-cell stimulus, the mean becomes about 70[sigma], or, in other words, nearly the same as the spinal reflex.  The conclusion seems forced, therefore, that when a stimulus reaches a certain intensity it produces the cord response, while until that particular point is reached it calls forth central activities which result in much longer and more variable reaction times.  It was said above that the series under consideration gave evidence of the gradual transition from the reflex to the volitional in reaction time. 

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