Subjective Light Pattern Spectroscopy in the Encephalographic Frequency Range

Effects of Chemical Stimulation of Electrically-Induced Phosphenes on their Bandwidth, Shape, Number and Intensity

“…(4) W hereas, as found in earlier work (K noll 1958, 1959, 1962) [26,29,30,28], electrically-induced phosphenes h av e m ostly the shape of ab stra ct-or ornam ental-type p a tte rn s, w ith only v ibrational-or re p eatin g -ty p e m ovem ent, th e drug-induced phenom ena also include landscapes and living or m an-m ade objects such as flowers, anim als, m achines and fast-m oving " firew ork" -type p a tte rn s.…”

“…L ately, (1958 [26]; 1959 [29]; 1959 [30]; 1962 [28]) b y using re c ta n g ular pulse frequencies w ith in th e E E G -range an d large (2 x 4 cm) tem p o ral or occipital electrodes, an objective m ethod has been devel oped which perm its th e ex citatio n an d control of phosphenes b y ex posing th e b ra in to electrical fields w ith o u t brain surgery. T he b a n d w id th of such p a tte rn s observed b y th e sam e individual has been found to v a ry (in all subjects investigated) only betw een 1 and 2 0 % of th e m ean frequency of th e pulse c u rre n t exciting them .…”

9. Johann Wolfgang von Goethe (1749–1832)

“…In contrast to other reports [62,63,66,67], the results of Experiment 1 suggest that there are different specific frequencies which are most effective in inducing the different subjective experiences. The categories of subjective forms and patterns reported by the observers in Experiment 1 can be compared not only to the subjective experiences induced by electrical stimulation [13], but also to the patterns described by Smythies [80].…”

“…Knoll and colleagues investigated geometric and specific subjective visual experiences induced by electric stimulation in great detail ( [66,67]; see also [13] for a review of this work). Similarly to the studies of Seidel et al [62,63] on magnetic stimulation, observers were blind-folded and presented with square-wave electric stimulation in the frequency range from 5 to 40 Hz.…”

Flicker-induced color and form: Interdependencies and relation to stimulation frequency and phase

“…While binocular stimulation yields clearer subjective patterns, the patterns become more finegrained with increasing stimulation frequency (Smythies compared stimulation frequencies of 6, 12, and 18 Hz). In a very similar vein, the work of Smythies corresponds with that of Knoll and Kugler (1959) who also showed subjective forms to be brought about through periodic electrical stimulation or by means of photic driving, i.e., as a function of exposure to high-frequency flicker. More recently, during an electroencephalographic (EEG) study of the cortical response to flickering light, Herrmann (2001) observed that most of his subjects reported forms (stars or stripes) and colors (blue, red, or purple).…”