TRANSACTIONS OF SUB-SECTION I. 679 
At times no image was reported, and at times two or three occurred in one 
experiment. Of the 251 images, 138 were reported as memory, 75 as imaginary, 
while 38 were equivocal. The images were all projected except in five instances 
for one observer, who described these as being ‘in his head.’ One observer 
placed all images upon the fixated disk. Another placed none there. The other 
four placed their images both on and off the disk. 
The nature of the method employed made it necessary to judge the localisa- 
tion of the image with reference to the disk. Thus there were four classes 
of localisation: (1) On the disk, (2) off the disk, but in the surrounding 
space, (3) at a distance, usually in the object’s proper environment, and (4) in 
an indefinite localisation. 
The correlation of the localisation with the nature of the image as memory 
or imaginary furnished some interesting results. The images of memory tended 
to be located at their proper place and distance, and the images of imagination 
tended strongly to be placed upon the disk. Those observers who placed few 
or no images upon the disk tended to locate images of imagination in the near-by 
space. For all who located their images variously there was a marked tendency 
to project the images of memory into the distance, and the images of imagination 
at or near the disk. 
In many instances there occurred a strong tendency to locate the image upon 
the disk irrespective of its nature as a memory or imaginary product. In such 
cases a marked inertia of the image was manifest. This applied to both classes 
of image; both resisted attempts to move them from their original location. 
This was especially marked in the attempts to remove memory images from a 
distant location to the disk. 
2. Hxperiments on Sound Localisation. By CuHartes 8S. Myers, 
M.A., M.D. 
The object of these experiments, which are still in progress, is to analyse 
the factors determining our (notoriously uncertain) localisation of sounds 
situated in the median (sagittal) line of the head. A sound-proof room was 
used, in which the subject and the experimenter sat; six subjects, giving 
twenty-five sittings, were investigated. The sounds were for the most part 
generated outside the room, to which they were led by means of a large 
trumpet and a tube. In most of the experiments the sound consisted of (1) a 
fundamental tone of (about) 200 vibrations per second, accompanied by its 
first three overtones (400, 600, 800 vibrations per second); these four tones 
were separately emitted from four wind-instruments operated by an assistant. 
In other experiments a buzzer was used as the source of sound, situated either 
(2) (as before) outside, or (3) within, the sound-proof room; in a few experi- 
ments, (4) an electric bell was sounded within the room. A noiselessly-moving 
instrument carrying either a funnel (or, when the sound was produced within 
the room, the buzzer or bell), served as a perimeter to vary the position of the 
sound in the room. Three positions of the sound were given—directly in front 
of (=0°), directly above (=90°), and directly behind (=180°) the subject. The 
subject, sitting blindfold, determined the apparent direction of the sound. The 
position of the subject in the room was variously changed. 
The subjects observed that their judgments were based on the timbre and 
loudness of the sounds (e.g., 0° is ‘the fullest, most open sound ’—90° is ‘a 
hoarse sound’) and on spatial experience, including medial incidence (e.g. 0° 
‘hits me full in the face ’—90° ‘has a vertical feeling’) and laterality (e.¢., 
“TI localise the front sounds by their being to the right ’—‘ The back sounds 
affect only the left ear’). Of these, laterality was due to the sound not being 
given exactly in the median line of the subject’s head; it was early seized on 
by the subjects as a criterion, but sooner or later it was of course necessarily 
abandoned. Medial incidence was also found to be an insecure basis. In the 
end, timbre and loudness proved the only reliable criteria. 
Experiments were later made with the sound (1), in which the loudness of 
the overtones was increased or diminished, thus varying the timbre of the whole 
‘sound. Experiments were also made with sounds (1) and (2), in which the 
