Approved For Release 2000/08/07 : CIA-RDP96-00788R001300350001-0 condition, opposite to what was seen in the first study. Further post- hoc statistical tests were not performed on the pass trials because the differences were clearly too small to reach significance. A very con- servative criterion is required for a post-hoc analysis of an isolated observation for which there are previous data in the opposite direction. The second factor in the trend toward a guess effect in the first experiment was an even greater alpha difference on those trials in which the subject guessed correctly. The correct guesses for the second experiment are shown in Table 6. The correct guesses without a sender show a small alpha increase in the active condition compared to Table 6 SECOND EXPERIMENT AT LANGLEY PORTER: CORRECT GUESS TRIAL MEANS, SHOWN AS NULL CONDITION/16-Hz CONDITION Lead: Referenced to Cz Oz to Linked O1 02 c3 c4 Oz Mastoids —— ——— Sender--Correct Guesses 0-4 s 518/463 561/497 291/233 348/276 463/407 481/445 a Means | 4-8 s 465/429 473/492 277/236 303/292 417/407 387/459 El 9.8 5 983/892 1034/989 568/469 651/568 880/814 868/904 Ration 0-45 1.12 1.13 1.25 1.26 1.14 1.08 “of 8| 4-8 1.09 0.96 1.17 1.04 1.02 0, 84 Means 1) 9.8 5 1,10 1,05 1.21 1.15 1.08 0.96 No Sender--Correct Guesses aj O48 425/449 469/505 284/256 356/298 386/420 529/540 Means 8] 4-8 s 421/411 456/453 302/262 331/306 394/406 496/585 Bl 5.8 5 846/860 925/958 586/518 687/604 780/826 1025/1125 Ratios 0-4 5s 0.94 0.93 lel 1.19 0.92 0.98 of 9| 4-88 1.02 1.01 1.15 1, 08 0.97. 0.85 Means =| 9.8 5 0,98 0.97 1.13 1.14 0.94 0.91 31 Approved For Release 2000/08/07 : CIA-RDP96-00788R001300350001-0
Approved For Release 2000/08/07 : CIA-RDP96-00788R001300350001-0 the null condition (not significant). Correct guesses with a sender show a small alpha decrease compared to the null condition, in the direction of the first experiment, but too small to be significant. Vv DISCUSSION In two studies, one at SRI and one in our laboratory, a decrease in EEG alpha power was observed as a function of remote photic stimulation, but at different scalp locations and in different time periods following the stimulus onset. The third study, on our laboratory, showed an in- crease in alpha power at another site and failed to replicate the original finding. Dr. Edwin May of SRI has done a full power spectral analysis of these data and reports that his analysis shows results similar to ours, We also observed that the subject's alpha frequency seemed to be slightly lower in the second experiment than the first, and Dr. May's analysis confirmed this. However we see no easy way to account for the negative or inconsistent experimental results in terms of frequency changes. We cannot account for this frequency change. The subject underwent major pelvic surgery in the three months between our first and second experi- ments, but there is no apparent reason to relate this to the EEG change. Statistical analysis of these data necessitated many significance tests on the same subject. One must always question the independence of such tests, and also keep in mind that 5% of them will be significant if the 0.05 level of confidence is adopted. In addition, repeated measures on one subject and simultaneous measurements from different leads always brings the independence of these measures into question. If the findings were replicable, the statistical questions would be less important. However, since there are many possibilities and we failed to replicate either our earlier finding or the SRI results, it is necessary to take a more conservative statistical position. The three separate experiments all show effects in the occipital cortex, but it is not the same effect, either in direction or site. We believe the 32 Approved For Release 2000/08/07 : CIA-RDP96-00788R001300350001-0
Approved For Release 2000/08/07 : CIA-RDP96-00788R001300350001-0 three experiments should not, therefore, be lumped together as jointly supporting each other: They could just as easily be taken as jointly nullifying each other, In conclusion, on each occasion, alpha changes occurred that differ from chance, but we could not reproduce the same effect, in either direction or site, There remains the possibility that a useful pheno- menon exists here, but if so, we have clearly not isolated the variables necessary to produce it at will. 33 Approved For Release 2000/08/07 : CIA-RDP96-00788R001300350001-0
Approved For Release 2000/08/07 : CIA-RDP96-00788R001300350001-0 Appendix SRI OPTICAL ISOLATION EXPERIMENTS AT LANGLEY PORTER 34 Approved For Release 2000/08/07 : CIA-RDP96-00788R001300350001-0
Approved For Release 2000/08/07 : CIA-RDP96-00788R001300350001-0 Appendix OPTICAL ISOLATION EXPERIMENTS AT LANGLEY PORTER 1, Introduction and Summary As described in Sections I-B and III-A of this report, the purpose of these measurements was to determine whether there exists any measur- able light leakage between the stimulus room in which a chopped light source operates, and the subject room in which EEG recordings are being made, Using phase~sensitive detection, a photomultiplier with an §-20 photocathode, and a synchronously chopped light source, we obtained a system sensitivity of 5 x 107? Wem” with unity signal-to-noise ratio, limited by photo~tube dark current. This sensitivity, in Wen’, is 3x 107}3 | down). Our findings using this equipment are as follows: of the flash lamp intensity used in our experiments (125 dB (1) In order to obtain a measurable light leakage signal it was necessary to open two of the three doors separating the stimulus room from the subject room (see Figure A-1) and direct the output of the flash lamp on the door frame of the subject room, Under these conditions a signal could be detected with 20:1 signal-to-noise ratio by the photomultiplier placed in the subject chair. (2) When any two of the three doors between the subject room and the flash lamp were closed, no signal could be detected, up to the measuring capability of the apparatus, with a 10-s integration time. (3) To examine the possibility of light transmission through the air conditioning ducts, we placed the photo-tube detector in the duct in the subject room and directed the output of the flash lamp on the duct in the stimulus room, Again, no detectable signal was found. From this investigation we find that to the limit of our measurement capability and under the conditions defined by the experimental protocols and geometry, there was no light leakage between the rooms in question; thus we conclude that the experimental findings of this program cannot be attributed to light leakage. 35 Approved For Release 2000/08/07 : CIA-RDP96-00788R001300350001-0
Approved For Release 2000/08/07 : CIA-RDP96-00788R001300350001-0 2. Laboratory Arrangement The laboratories evaluated in this experiment consist of two groups of rooms on either side of a hallway. (See Figure A-1.) The doors of the two laboratories face each other as they open onto a hall. The stimulus room housing the lamp is a single room with one door. The sub- ject room is entered from the hall, by first passing through a control room housing EEG recording equipment. The subject room is considered a darkroom, and has windows on the outer wall (opposite the control room) that are taped and boarded up. A small but visible amount of light enters the room around the tape. The room is separated from the control room by a wooden door having plastic weather stripping on its edges, as have the outer doors of both labs, Thus, from where the subject sat in the dark room, the light from the stimulus room would have had to pass through three closed and sealed doors to reach her, 3. Apparatus The light-detecting system used in this measurement is shown in Figure A-l. An electron multiplier photo-tube (RCA 7265) is powered by an 1800-V de power supply, and its anode current is measured across a 100-kilohm resistor, The voltage thus developed goes to the input channel of a PAR (Princeton Applied Research) phase~sensitive detector, having a tuned input filter, phase-sensitive amplifier, and variable time con- stants, We derive the reference signal for the amplifier from a small photodiode taped to the face of the chopped light source in the stimulus room. The chopping frequency is 16 Hz, The output of the light source was measured with a 16-junction Eppley thermopile and a microvoltmeter, This measurement gave an intensity of 15 mW/om” at 10 em from the light source, Using this now-calibrated light source, together with calibrated neutral density filters, we measured the sensitivity of the phototube -15 and phase-sensitive detector to be 5 x 10 Wem’, with an integrating time constant of 10 s. 36 Approved For Release 2000/08/07 : CIA-RDP96-00788R001300350001-0
Approved For Release 2000/08/07 : CIA-RDP96-00788R001300350001-0 4. Results In these experiments the conditions were exactly as they were during the actual EEG experiments described in detail in Section IV-A of Part 2 of this report, In particular, there was a small amount of outside day- light leaking into the subject room through the electrical tape used to seal the window cracks, This was quite a small amount of light, amounting to approximately six times the dark current of the phototube--ti.e,, 3 xX 10714 W/em?, This amount of light is barely detectable to the dark- adapted eye, but does give rise to incoherent shot noise in the phototube, increasing the magnitude of the minimum detectable signal. The subject room and the light stimulus room are connected to a common air-conditioning system. The air-conditioner ducts make eleven right-angle bends in traversing the 30 feet between the two rooms, and this ducting was a prime suspect for possible light leakage between the two rooms. To determine the presence of such leakage, the phototube was placed inside the duct in. the subject room, and the light stimulator had its output directed at the duct in the stimulus room (even though this was not the condition during actual experiments, when it was pointed toward the side wall of the room). With the phototube in the duct, its background was no longer determined by the ambient light in the room, but rather by phototube dark current, giving a phase-sensitive amplifier reading of 5 wV, corresponding to 5 x 10719 Wem’, This signal was not affected by the presence or absence of light from the flash lamp directed at the other end of the air-conditioning duct. In measurements with the flash lamp directed along a vector across the intervening hall toward the door frame and closed door of the experimental room, no position or manipulation of the flash lamp produced any effect whatever on the output of the phase-sensitive detector. A signal could be detected only when both of the two hall doors of the laboratory rooms were left open to allow the light to leave and enter the rooms (a condition counter to those set up during experimentation). The signal in this case was twenty times the shot noise background due to ambient light in the darkroom, with its door closed. 38 Approved For Release 2000/08/07 : CIA-RDP96-00788R001300350001-0