Approved For Release 2000/08/08 : CIA-RDP 6-00789R002200170001-9 i _ a. Lo - has been mixed.) The object used for the experiment was the wreck of a Spanish galleon, Nuestra Senora de Atocha, which sank during a hurricane in 1622. The wreckage was found off the coast of Key West, Florida, on 20 July, 1985. It was selected as the target for this experiment because, although its location was already known, the considerable wealth it contained and its fascinating historical background made it something that would have been worth searching for. The purpose of this task was to simulate a situation in which the searchers would be excited about finding the target because of its value. Of course the experiment was designed in such a way that knowing the actual location of the wreckage would not help the searchers succeed in the experiment. 1. (U) Preliminary Activities (U) To create a high level of interest in the experiment, SRI personnel visited Florida and conducted two preliminary activities. First, they accompanied Viewer 198 to the Atocha museum and discussed the experiment and the Atocha history in detail with him/her. Later, before beginning the experimental trials, Viewer 198 showed a National Geographic videotape of the search for the Atocha to the other four participants. (U) The second preliminary activity was to conduct a few real-world search trials with Viewer 198, for a less important, but known, Spanish galleon wreck, the San Pedro. For these trials the location of the San Pedro wreck was marked on a map. Three white paper disks, scaled to correspond to 5,000 yards in diameter (6.34 square miles), were randomly keyed to the map and marked with a secret orientation code so that the experimenter could later rematch them to the map. The actual map location of the San Pedro was constrained to be somewhere on each of the three disks. (U) To add to the excitement of the task, the data were collected while Viewer 198 and the SRI personnel were in a vessel anchored directly above the wreck. Viewer 198 was given the three disks and asked to mark on each of them the spot where he/she felt the wreck and thus his/her current location were. We had hoped that “searching” for yourself as a beacon would contribute to the success of the trial. (U) Each disk was rematched to the map and the center of gravity (CG) for the three responses was calculated.. Viewer 198’s CG corresponded to a spot 500 yards from the wreck. If 7 ; Approved For Release zoning : CIA-RDP96-00789R002200170001-9
4 Approved For Release 2000/08/08 : CIA-RDP96-00789R002200170001-9 (U) a “real search” had been initiated at Viewer 198’s spot, a 96% reduction in search area would have been realized over starting at a random location. (U) Encouraged by this demonstration trial, we proceeded with the search for the Atocha. 2. (U) Experimental Details (U) The five participants in the Atocha experiment conducted their searches in group meetings at one participant’s home. During each weekly meeting, each subject attempted five guesses. These were recorded by filling in a square on a piece of paper containing a 20 x 20 grid similar to that shown in Figure 1. These responses were then mailed to SRI International for evaluation. Previous to the time of the meeting, an experimenter at SRI had generated a target square for each participant, for each of the trials. This was done using a computer randomization schemie to select one of the 400 squares in the grid. To simulate real conditions as much as possible, the grid was placed on a map of the Key West area with the target square centered on the spot where the Atocha had been found. Thus, each week there were five such grids, ordered numerically by trial number, for each participant. If the participant filled in the correct square on a given response grid, then when the grid used for that trial was placed on the map, the response would be directly over the spot where the Atocha was found. (U) The experiment was initially scheduled to run for five weeks, with each participant contributing a total of 25 trials. However, at the end of that period the participants submitted and were granted a request to repeat the experiment, so the entire experiment consists of two sets of 25 trials for each subject. Cc. (U) Analysis (U) In both the CAS and the Atocha experiments, the basic unit of data for analysis consisted of sets of 25 target/response pairs. Within each pair, the data recorded were the coordinates of the target and the response from their locations on the 20 x 20 grid. In the CAS experiment, each of the eight subjects contributed one such set in the time condition and one in the space condition. For the Atocha experiment, each of the five subjects contributed two sets, one during each of the two five-week periods in the experiment. fo interest is Whether or not the information provided by the participant the question of 8 )8/08 : CIA-RDP$6-00789R002200170001-9 4 \ ¥ Approved For Release 20
(S-NF ) 4 Major Keyword Miscellaneous-~Encompasses all OO j publications that were determined to possess little or no immediate thauntings,' detection of the human aura, and so forth) Approved For Releas 00/08/08 : C DP96-00789R002200170001-9 Table 6 (concluded) Subtopic Keyword No subtopics as yet implemented p interest (e.g., Approved For Release 2000/08/08 : CIA-RDP96-00789R002200170001-9
Approved For Release a ie : CIA-RDP96-00789R002200170001-9 | ¥ « would help reduce the time needed to find the target. This is equivalent to reducing the area over which it is necessary to search before the target is located. (U) Assume that in the absence of any information, a search would proceed by randomly selecting a square on the grid and searching that square. If the target is not found, then the squares closest to the original one are searched, in random order. This continues, by progressively moving away from the original square, until the target is found. At each stage, the set of squares equidistant from the original one, which have not yet been searched, are selected in random order and searched. (U) To analyze the success of these experiments, the average time required to find the target using this procedure with the subject’s guess as the starting point should be compared to the average time required using a random starting point. (U) The number of squares that must be searched could range anywhere from one (if the target is in the original starting square), to the total number of squares, which is 400 for our experiments. In the absence of any information, and assuming that the target is equally likely to be anywhere in the grid, the probability that exactly s squares must be searched is 1/400, for any integer value of s from one to 400. In other words, s follows what is called a “discrete uniform distribution.” It is as likely that all 400 squares will have to be searched as it is that the target will be found in the first square. This result is independent of the starting square. (U) The item of interest from each trial is the number of squares that would have to be searched to find the target. To compute this, we first find the straight line distance from the response to the target using the formula: d=y7 (Y,- Y,)? + (X, - X,)?, where (X,, Y; ) and (Xz, Y2) are the coordinates of the target and the response, respectively. (U) Next, we count the number of squares that are closer to the response than is the actual target, since all of those would have to be searched before the target would be found. Finally, we add to the count half of the number of squares that are exactly d units from the response, since on the average half of the squares at that distance would have to be searched Approved For Release zpqfoand : iy aan
¢ : Para Approved For Release 2000/08/08 : CIA-RDP96- 00789R002200170001 nan UNCLASSIFIED (U) on before finding the one with the target. In symbols, if we define p as the proportion of squares can that must be searched to find the target, then: . r<d 2 n(D,) + 0.5 n(D, ) r=0 a 400 where n(Dr) represents the number of squares exactly r units from the response. One advantage of working with these proportions is that we can estimate a meaningful quantity, the expected reduction in area searched, instead of simply testing for significance. (U) To determine whether or not a given set of 25 trials produced a result significantly different from chance, we compare the average proportion of the grid searched to what would be expected by chance. We can compute a z-score by subtracting the expected average, which is 0.5 x (201 — 400) = 0.50125, from the average p, then dividing by the standard deviation, which s /1/12n . Thus, = ¥12n (0.50125-p). In this case, n = 25.0 Using the Central Limit Theorem, a set of 25 trials will be declared to be significant if z << -1.645. (U) The p-value for an entire experiment will be based on the minimum p-value across all subjects. If there are N subjects, the appropriate formula for this will be overall p-value = [1 — (1 - min p-value) ] 2 ‘ (U) This formula is based on the minimum of N independent samples from a standard uniform distribution. Under the null hypothesis, p-values should follow such a distribution. This procedure was introduced by Tippett in 1931, and was the first test of significance based on combined results.2 It is most powerful when one or more subjects can produce a large effect, even if others cannot. This seems to be a good model for what appears to be happening in psi research, so this procedure would be appropriate.