Effects of Smoking on Mental and Motor Efficiency? Conclusion
- Author:
Oscar J. Johnson,
University of Minnesota. Experiment II.
It has been mentioned before that the method in this experiment was to have the four subjects practice the tests until they ceased to improve and then to have them smoke in order to observe the results. These smoking tests were held the evening of Friday or Saturday of each week for four weeks. Each subject usually took all of the tests at 4.30 p. m. and immediately afterward smoked a cigar. As soon as it was smoked, the tests were gone through again and were afterward repeated at intervals of one hour until ten o’clock. They were also gone through twice the next morning, but in no case were any measureable effects found. In fact, from three to four hours after smoking the performances were so nearly normal again that the deviations might well have been accidental.
Tests Used: 1. Aiming: Steadiness of Motor Control; 2. Tapping Test; 3. Color Naming Test; 4. Addition Test; 5. Steadiness Test. The materials used in tests 1 and 5 consisted of the brass plate and accessory apparatus described in Whipple’s Manual, page 157. In test 5, the subject attempted to hold the stylus in the smallest hole of the plate for 15 seconds twice, without touching the sides of the hole. In both 1 and 5 the number of contacts was the measure used; in Number 2, the average number of taps in two periods of 30 seconds each; in number 3 the time taken to name one hundred colors; and in number 4 the time taken to add seven to one hundred twoplace numbers. There are five tables giving the main results of this experiment; the sixth table gives a summary of five other tables omitted for lack of space. This one shows the immediate effect of smoking on the various functions, and the disturbances are quite large as compared with the average of three performances one hour between. Aiming: Steadiness of Motor Control.
From table I it will be seen that in the four smoking tests there were 321.2 per cent, more contacts after smoking than before for 230
subject I., when the average of three tests was used as the measure. The increase for K was 13.1 per cent.; for R, 22C.5 per cent., and for J., 68.4 per cent. That is to say, that for every contact before smoking there were 1.48 after smoking. By glancing at table VI, it will be seen that the immediate effects are a great deal larger, being 633.3 per cent, for I.; 72.9 per cent, for K; 533.3 per cent, for R; and 130.4 per cent for J., making an average of 342.5 per cent. This means 3.42 contacts immediately after smoking to every one when not under the influence of tobacco.
Tapping Test.
Here an increase in number of taps means improvement. On an average for the four smoking series, only R increased his performance, and this by 1.4 per cent only; I dropped 3.5 per cent; K, 4.9 per cent; and J, 7 per cent, thus making an average drop of 3.7 per cent for all tests for all subjects. Curiously enough, this result is larger than that obtained when the immediate effects were measured, the falling off in performance being only 3.4 per cent. This is due to the low mark made by J here which is 2.1 per cent compared with 7.7 per cent in the other case. The effects of smoking are clear and consistent for almost every test, although not so large as in aiming.
Color Naming.
Table II shows that it took K 4.2 per cent longer to name 100 colors after smoking than before; R 2.4 per cent longer and J 0.3 per cent, shorter, making the average time of three tests an hour between after smoking 2.1 per cent longer than before smoking. Table VI shows that the average for the three subjects in the test immediately after smoking is 11.5 per cent longer than before smoking, subjects R and J having their times increased 14.7 per cent, and 14.2 per cent, respectively, while K’s is only 6.1 per cent, longer.
Addition Test:
Here we have rather unexpected results in that the time to add is shortened considerably in most instances. This is especially true of R who found that smoking stimulated both his efficiency and accuracy to a remarkable extent, which decreased as time went on until he again reached the normal after a few hours. For J the time was increased slightly, making the total decrease for the three subjects 2.4 per cent. K displayed irregularities in performance; it will be seen in table VI that his time in the test immediately after smoking is 7.4 per cent longer than before smoking, while in table IV, including two subsequent tests, the time is 1.0 per cent less. R’s results are consistent in the two cases.
Steadiness Test.
This test is especially adapted to show slight tremors of the hand and arm muscles, and we find that smoking increases them very decidedly. Table V shows that the increases in number of contacts for I is 86.4 per cent; for K 20.7 per cent; for R 33.3 per cent; and for J a decrease of 40.0 per cent. The results for J are not very conclusive either in this or the other tests as this subject was unable to take more than one smoking series. The average increase in contacts for all four subjects in the three tests after smoking is 25.1 per cent, as compared with 192.2 per cent in the test immediately following smoking. The individual scores are given in the last column of table VI.
It will be noted that in experiment II no attempt has been made to measure the number of errors. The only account taken of them was to have the subject stop and correct himself whenever he made any. The only data gathered are those of the time taken to a-definite amount of work, or of the amount of work done within a specified time.
The results prove that the effects of smoking are very detrimental to muscular control and also to the purely mental processes studied. This confirms the results of experiment I. There are some individual differences, as with subject R in addition and K in aiming, which are too large for chance variations, but might be explained on other grounds which are so purely hypothetical as not to be dealt with here. In a larger number of tests, it would probably be found that the ones showing a positive aid from smoking would be so small as not to be of any especial significance.
The following table is a summary of the main results. It shows the effect on performance immediately after smoking and two hours after smoking for all subjects for all tests in experiment II. The figures are averages.
Per Cent decrease in Performance. Rioht After Smokino. Two Hours After. 1. Aiming: Steadiness of Motor Control (Increase in errors) 2. Steadiness (Increase in errors) 3. Color Naming (Increase in time) 4. Tapping (Decrease in No. of taps)…. 5. Adding (Increase in time)… 624.5% 192.2% 11.5% 3-4% 2-4% 132.9% 13.7% 5.3% 6.4% 5.1%
Experiment II.?Table I. Aiming Test. Numbers are averages of three performances before and three after smoking for each smoking test, the tests after smoking being given at intervals of one hour.
Subjects First Smoking Tost 1 Second Smoking Test 1 Third Smoking Test Fourth Smoking Test Aver, of Differ2.3 64.0 2.0 26.3 12.3 49.6 7.3 44.3 434.8 -22.5 265.0 68.4 1.5 55.6 2.0 6.0 30.0 8.6 % 300.0 -46.0 330.0 0.5 2.5 3.0 2.0 1.0 5.0 % 300.0 -40.0 66.6 1.0 1.0 3.5 2.6 % 250.0 160.0 % 321.2 13.1 220.5 68.4 Average per cent iilTercncc between 2 and 1 1S6.3 194.6 10S. 205.0 148.8
Explanation.
Under 1 are given the average number of contacts in three trials before smoking.
? Under 2 arc given the average number of contacts in three trials after smoking.
3. Under 3 are given the difference in per cents between 1 and 2. Increase in number of contacts means decrease in performance.
Experiment II.?Table II. Tapping Test. Showing averages of three performances before and three after smoking for each smoking test, the tests after smoking being given at intervals of one hour. rful)jects First Smoking Test 239.0 294.0 267.0 231.0 232.0 306.0 2S3.0 213.0 Average per ccnt difference between 2 and 1 % -2.9 4.0 5.9 -7.7 -.17 Second Smoking Test 247.0 299.0 280.0 245.0 266.0 286.0 % -.8 -11.0 2.1 -3.2 Third Smoking Test 257.0 281.0 282.0 213.0 234.0 271.0 % -5.4 -16.7 -3.9 -8.6 Fourth Smoking Test 237.0 290.0 225.0 302.0 % -5.0 4.1 -4.5 Aver, of Differ % -3.5 -4.9 1.4 -7.7 -3.7
Explanation.
Under 1 arc given the verage number of taps in three trials before smoking.
Under 2 are given the average number of taps in three trials after smoking.
3. Under 3 arc given the difference in per cents between 1 and 2. Increase in number of taps means improvement in performance.
Experiment II.?Table III. Color Naming Test. Showing averages of three performances before and three after smoking for each smoking test, the tests after smoking being given at intervals of one hour. Subjects First Smoking Test Second Smoking Test Third Smoking Test Fourth Smoking Test Aver, of DitTer44.3 55.0 47.3 44.0 55.0 47.2 .7 -1.1 -.3 43.0 55.0 45.3 58.3 % 3.8 4.8 40.5 55.5 45.5 57.0 13.5 3.7 43.3 42.7 -1.3 % 4.2 2.4 -.3 Average per cent difference between and 1 4.3 -1.3 2.1
Explanation. 1. Under 1 are given the average length of time for three trials in naming 100 colors before smoking. 2. Under 2 are given the average length of time for three trials in naming 100 colors after smoking 3. Under 3 are given the diffcrcnccs in per cents between 1 and 2. Longer time under 2 indicates poorer performance after smoking.
Experiment II.?Table IV. Addition Test. Showing averages of three performances before and three after smoking for each smoking test, the tests after smoking being given at intervals of one hour. Subjects First Smoking Test Second Smoking Test Third Smoking Test Fourth Smoking Test Aver, of Differ cnccs. 44.3 100.6 88.0 44.1 97.0 89.0 % -.2 -10.9 1.8 43.G 94.0 45.3 92.0 % 3.9 -2.1 01.0 92.0 58.0 82.0 % -5.0 -10.8 02.0 00.3 % -2.7 % -1.0 -7.9 1.8 Average per cent difference between 2 and 1 3.1 -7.9 -2.7 -2.4
Explanation.
Under 1 are given the average length of time of three trials at adding before smoking.
Under 2 are given the average length of time of three trials at adding after smoking.
3. Under 3 are given the differences in per cents between 1 and 2. Longer time under 2 indicates poorer performance after smoking.
Experiment II.?Table V. Steadiness Test. Showing the averages of three performances before and three after smoking for each smoking test, the tests after smoking being given at intervals of one hour. Subjects First Smoking Test Second Smoking Test Third Smoking Test Fourth Smoking Test Aver, of Differ 5.0 11.0 3.3 3.5 5.1 1C.0 5.1 2.1 % 2.0 45.4 54.5 -40.0 2.5 7.7 3.0 3.0 4.0 20.0 14.3 53.3 2.7 3.0 2.5 8.2 3.2 2.3 % 203.7 G.O -8.0 1.5 3.0 3.3 3.5 % 120.0 10.6 % 80.4 20.7 33.3 -40.0 Average per cent difference between 2 and 1 15.5 30.9 72.8 25.1
Explanation.
Under 1 are given the average number of contacts for three series of two trials each before smoking.
Under 2 are given the average number of contacts for three series of two trials each after smoking.
3. Under 3 are given the differences in per cent between 1 and 2. A larger number of contacts under 2 indicates poorer performance after smoking.
Experiment II.?Table VI.
This table is condensation of five tables made up in the same manner as I, II, III, IV, and V, except that instead of giving the averages of three performances before and of three after smoking, they represent the averages of three performances before smoking, but give the results of the first series of tests immediately after smoking, thus showing the most pronounced effects possible in this experiment. Only the columns “Average of Differences” from each of the other tables is given here.
Aiming Test Tapping Test Color Naming Test Addition Test Steadiness Test Subjects Average of Differences Average of Differences Average of Differences Average of Differences Average of Differences I K R J Average. 033.3% 72.9% 533.3% 130.4% 342.5% -5.5% -3.6% -2.3% -2.1% -3.4% C.1% 14.7% 14.2% 11.5% 7.4% -10.1% 9.8% 2.4% 197.5% 307.9% 235.1% 28.5% 192.2%
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