Sixteen Experimental Investigations from the Harvard Psychological Laboratory by Hugo Münsterberg (100 books to read .txt) 📕

these differing modes of expression embody are to be made the subject

of experimental investigation their characteristic structures should

be kept intact as objects of analysis in independent experiments,

instead of being combined (and modified) in a single process.

The apparatus employed in the course of the present investigation

consisted of four different pieces of mechanism, one affording the

vehicle of expression throughout the series of reproduced rhythms, the

others providing the auditory material of the various rhythms

apperceived but not designedly reproduced. The first of these

consisted of a shallow Marey tambour, placed horizontally upon a table

with its rubber film upwards, and connected by means of rubber-tubing

with a pneumographic pen in contact with the revolving drum of a

kymograph. A Deprez electric marker, aligned with the pneumographic

stylus, afforded a time record in quarter seconds. Upon this tambour,

placed within comfortable reach of the reactor’s hand, the various

rhythm types were beaten out. The impact of the finger-tip on the

tense surface of the drum gave forth a faint and pleasing but at the

same time clearly discernible and distinctly limited sound, which

responded with audible variations of intensity to the differing

stresses involved in the process of tapping, and which I have

considered preferable to the short, sharp stroke of the Kraepelin

mouth-key employed by Ebhardt. The rate of revolution in the drum was

so adjusted to the normal range of excursion in the pneumographic pen

as to give sharp definition to every change of direction in the curve,

which hence allowed of exact measurements of temporal and intensive

phases in the successive rhythm groups. These measurements were made

to limits of 1.0 mm. in the latter direction and of 0.5 mm. in the

former.[2]

[2] Professor Binet’s doubt (_L’Année Psychologique_ 1895, p.

204) that the propulsion of air from the elastic chamber and

the rebound of the pen might interfere with the significance of

the graphic record is more serious in connection with the

application of this method to piano playing than here; since

its imperfection, as that writer says, was due to the force and

extreme rapidity of the reactions in the former case. The

present series involved only light tapping and was carried on

at a much slower average rate.

The second piece of apparatus consisted of an ordinary metronome

adjusted to beat at rates of 60, 90, and 120 strokes per minute. This

instrument was used in a set of preliminary experiments designed to

test the capacity of the various subjects for keeping time by finger

reaction with a regular series of auditory stimulations.

The third piece of apparatus consisted of an arrangement for producing

a series of sounds and silences, variable at will in absolute rate, in

duration, and, within restricted limits, in intensity, by the

interruptions of an electrical current, into the circuit of which had

been introduced a telephone receiver and a rheostat. Portions of the

periphery of a thin metallic disc were cut away so as to leave at

accurately spaced intervals, larger or smaller extents of the original

boundary. This toothed wheel was then mounted on the driving-shaft of

an Elbs gravity motor and set in motion. Electrical connections and

interruptions were made by contact with the edge of a platinum slip

placed at an inclination to the disc’s tangent, and so as to bear

lightly on the passing teeth or surfaces. The changes in form of a

mercury globule, consequent on the adhesion of the liquid to the

passing teeth, made it impossible to use the latter medium. The

absolute rate of succession in the series of sounds was controlled by

varying the magnitudes of the driving weights and the resistance of

the governing fans of the motor. As the relation of sounds and

intervals for any disc was unalterable, a number of such wheels were

prepared corresponding to the various numerical groups and temporal

sequences examined—one, for example, having the relations expressed

in the musical symbol 3/4 | >q e |*; another having that represented in

the symbol 4/4 | >q e e |;* and so on. Variations in intensity were

obtained by mounting a second series of contacts on the same shaft and

in alignment with those already described. The number of these

secondary contacts was less than that of the primary connections,

their teeth corresponding to every second or third of those. The

connections made by these contacts were with a second loop, which also

contained within its circuit the telephone receiver by which the

sounds were produced. The rheostatic resistances introduced into this

second circuit were made to depart more or less from that of the

first, according as it was desired to introduce a greater or slighter

periodic accent into the series. This mechanism was designed for the

purpose of determining the characteristic sequences of long and short

elements in the rhythm group.

*Transcriber’s Note:

The original article showed “3/4 | q q q |” and “4/4 | q q q q |”.

Applying the erratum after the article (below) resulted in

fewer beats per measure than indicated by the time signature.

Other possibilities are “3/4 | >q e q. |” and “4/4 | >q e e q q |”.

“ERRATUM:

On page 313, line 23, the musical symbols should be a quarter

note, accented, followed by an eighth note; in the following

line the symbols should be a quarter note, accented, followed

by two eighth notes.”

The fourth piece of apparatus consisted essentially of a horizontal

steel shaft having rigidly attached to it a series of metallic

anvils, fifteen in number, on which, as the shaft revolved, the

members of a group of steel hammers could be made to fall in

succession from the same or different heights. The various parts of

the mechanism and their connections may be readily understood by

reference to the illustration in Plate VIII. On the right, supported

upon two metal standards and resting in doubly pivoted bearings,

appears the anvil-bearing shaft. On a series of shallow grooves cut

into this shaft are mounted loose brass collars, two of which are

visible on the hither end of the shaft. The anvils, the parts and

attachments of which are shown in the smaller objects lying on the

table at the base of the apparatus, consist of a cylinder of steel

partly immersed in a shallow brass cup and made fast to it by means of

a thumb-screw. This cup carries a threaded bolt, by which it may be

attached to the main shaft at any position on its circumference by

screwing through a hole drilled in the collar. The adjustment of the

anvils about the shaft may be changed in a moment by the simple

movement of loosening and tightening the thumb-screw constituted by

the anvil and its bolt. The device by which the extent of the

hammer-fall is controlled consists of cam-shaped sheets of thin wood

mounted within parallel grooves on opposite sides of the loose collars

and clamped to the anvils by the resistance of two wedge-shaped

flanges of metal carried on the anvil bolt and acting against the

sides of slots cut into the sheets of wood at opposite sides. The

periphery of these sheets of wood—as exhibited by that one lying

beside the loose anvils on the table—is in the form of a spiral which

unfolds in every case from a point on the uniform level of the anvils,

and which, by variations in the grade of ascent, rises in the course

of a revolution about its center to the different altitudes required

for the fall of the hammers. These heights were scaled in inches and

fractions, and the series employed in these experiments was as

follows: 1/8, 2/8, 3/8, 5/8, 7/8, 15/8, 24/8 inch. Upon a

corresponding pair of standards, seen at the left of the illustration,

is mounted a slender steel shaft bearing a series of sections of brass

tubing, on which, in rigid sockets, are carried the shafts of a set of

hammers corresponding in number and position to the anvils of the

main axis. By means of a second shaft borne upon two connected arms

and pivoted at the summit of the standards the whole group of hammers

may at any moment be raised from contact with the cams of the main

shaft and the series of sounds be brought to a close without

interrupting the action of the motor or of the remainder of the

apparatus. By this means phases of acceleration and retardation in the

series, due to initial increase in velocity and its final decrease as

the movement ceases, are avoided. The pairs of vertical guides which

appear on this gearing-shaft and enclose the handles of the several

hammers are designed to prevent injury to the insertions of the hammer

shafts in their sockets in case of accidental dislocations of the

heads in arranging the apparatus. This mechanism was driven by an

electrical motor with an interposed reducing gear.

[Illustration: PSYCHOLOGICAL REVIEW. MONOGRAPH SUPPLEMENT, 17. PLATE VIII.

Opposite p. 314.]

The intervals between the successive hammer-strokes are controlled in

the following way: on the inner face of the group of pulleys mounted

on the main shaft of the mechanism (this gang of pulleys appears at

the extreme right in the illustration) is made fast a protractor

scaled in half degrees. Upon the frame of the standard supporting

these pulleys is rigidly screwed an index of metal which passes

continuously over the face of the scale as the shaft revolves. The

points of attachment (about the shaft) of the cams are determined by

bringing the point of fall of each cam in succession into alignment

with this fixed index, after the shaft has been turned through the

desired arc of its revolution and made fast by means of the

thumb-screw seen in the illustration at the near end of the shaft.

Thus, if three strokes of uniform intensity are to be given at equal

intervals apart and in continuous succession, the points of fall of

the hammers will be adjusted at equal angular distances from one

another, for example, at 360°, 240°, and 120°; if the temporal

relations desired be in the ratios 2:1:1, the arrangement will be

360°, 180°, 90°; if in the ratios 5:4:3, it will be 360°, 210°, 90°;

and so on. If double this number of hammers be used in a continuous

series the angular distances between the points of fall of the

successive hammers will of course be one half of those given above,

and if nine, twelve, or fifteen hammers be used they will be

proportionately less.

An interruption of any desired relative length may be introduced

between repetitions of the series by restricting the distribution of

angular distances among the cams to the requisite fraction of the

whole revolution. Thus, if an interruption equal to the duration

included between the first and last hammer-falls of the series be

desired, the indices of position in the three cases described above

will become: 360°, 270°, 180°; 360°, 240°, 180°, and 360°, 260°, 180°.

In the case of series in which the heights of fall of the various

hammers are not uniform, a special adjustment must be superimposed

upon the method of distribution just described. The fall of the hammer

occupies an appreciable time, the duration of which varies with the

distance through which the hammer passes. The result, therefore, of an

adjustment of the cams on the basis adopted when the height of fall is

uniform for all would appear in a reduction of the interval following

the sound produced by a hammer falling from a greater height than the

rest, and the amount of this shortening would increase with every

addition to the distance through which the hammer must pass in its

fall. In these experiments such lags were corrected by determining

empirically the angular magnitude of the variation