brenda j. dunne et al- series position effects in random event generator experiments

8/3/2019 Brenda J. Dunne et al- Series Position Effects In Random Event Generator Experiments

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Journal of Scientific Exploration, Vol. 8, No. 2, pp. 197-215, 1994 0892-3310/94 1994 Society fo r Scientific Explora t ion

Series Position Effects In Random Event GeneratorExperiments

B R E N D A J . D U N N E , Y O R K H . D O B Y N S , R O B E R T G . J A H N , R O G E R D . N E L S O Nwith an Appendix:

"Serial Position Effects in the Psychological Literature"B Y A N G E L A T H O M P S O N

Princeton Engineering Anomalies Research, C-131 Engineering Quadrangle, Princeton U n i v e r s i t y ,Princeton, N J 0 8 5 4 4

Abstract Effect sizes achieved by h u m a n operators in random event gen-erator anomalies experiments show correlations with th e ordinal positions ofth e experimental series in both th e collective an d individual databases.Specifically, there are statistically significant tendencies for operators to pro-duce better scores over their first series, then to fall off in performance intheir second an d third series, an d then to recover to some intermediate levelsduring their fourth, fifth, an d subsequen t series. Such correlations appear inboth local an d remote experiments, and are also indicated over a sequence ofdifferent experimental protocols, but no similar effects are found in baselineor calibration data. These serial position patterns t hus appear to be primarilypsychological in origin, and may s ub sume th e rudimentary "decline," "pri-macy," "recency," an d "term inal" effects propounded in the parapsychologi-cal and psychological literature. The results also emphasize th e importanceof very large individual databases in determ ining the asym ptotic effect sizesin any given experim ent of this type.

IntroductionCasu al re trospective exam inat ions of the h u ge rand om even t generator (REG)databases acqu i red over fou r teen years of exper im entat ion in th is laboratory(Nelson & Dob yn s , 1991) hav e suggested that cer ta in su bt le pat terns of opera-tor perform ance associated w ith the degree of experience wi th given d evicesand/or protocols may reside therein. For exam p le, the largest coherent subsetof REG d ata , acqu i red u s in g s ingle operators proxim ate to a m achine d r ivenby a m icroelectronic diode noise sou rce, displays a statistical pattern of scorestha t correlate w ith th e ordinal pos it ion of the experim ental series in the opera-tor data sets. More specifically, it appears that early success in the first seriesis su b stan t ia l ly decreased in the next series or t w o , an d then recovers over th enex t few series, at least partially, to com par atively stable success levels.These im press ions are rem iniscent of v ar iou s a l lu s ion s to "decl ine ef fects ,""position effects," or "learning effects" in the parapsychological l i tera ture ,and to observations reported in the broader psychological dom ains of learn-

197


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198 B. J. D u n n e , Y. H. Dob yn s, R. G. Jahn , and R . D. Nelsoning, m em ory, attention, and v igilance (cf A ppen dix). For exam ple, Rhine andH u m p h r e y describe temporal effects in ESP experim ents wherein the scoringis more extreme at the ends of r un s than in the middle, leading to U-shapedscore patterns (Rhine & H u m p h r e y , 1944). Rhine later refers to "patterns of bitf requency that relate to the structure of the test," an d notes tha t adu l t s displaysuch pat terns more marked ly than chi ldren; that the effects are more pro-nounced in experim ents wh ere operators work withou t an observer an d wherethey are aware of their progress as the test progresses; and tha t these t rendsm ay be observed from the level of the trial up to that of the fu l l exper im ent(Rhine, 1969).In th e hope of clarifying such serial position effects, w e have undertaken amore detailed an d quanti tat ive analysis of possible correlations of REG scoreswith series order. The single operator, local, diode database em ployed for thispu rpose com prises som e 2.5 m ill ion total trials arrayed in 522 experim entalseries of varying sizes, generated by 91 i nd iv idua l operators. Since details ofthese experim ents have been reported elsewhere (Nelson & Dobyns , 1991;Nelson , Dun ne , & Jahn , 1984; J ah n , D u n n e , & Nelson, 1987; Jahn & D u n n e ,1987; Nelson, Bradish, & Dobyns, 1989; Jahn, Dobyns, & Dunne , 1991;D u n n e & Jahn, 1993), here w e will s imply summar i ze th e pertinent term s andconditions. A tripolar protocol requires operators to intersperse efforts to pro-duce count s higher or lower than the theoretical expectation, with baselineswhe re the m achine is operated w ithout any explicit inten tion. A trial consistsof 200 random binary digits, typically generated at 1000 per second, which arecom pared with a regularly alternating + - + - . . . sequence . Th e n u m b e r of con-forming bits is displayed v ia LEDs on the face of the device, and autom aticallyand redun dan t ly recorded in a com pu ter ized da ta m anagem ent sys tem. Trialsare generated in runs of 50, 100, or 1000, depending on operator preference orprotocol constraint. I n m ost cases, the trials are au tom atically sequenced aftera single but ton press, although they m ay also b e produced in a m a n u a l m o d ewhere each trial is independ ently initiated. A n experimental ser ies , which isth e basic statistical u n i t of these experim ents, constitutes an independent ex-periment of a predeterm ined n u m b e r of trials generated u n de r each of the threeintentions of "high," "low," "baseline" with all other conditions held constant.In one protocol ("vo lition al"), the intended d irections are selected b y the oper-ator, with a constraint on b alance, prior to the trials. In an alternative protocol("instructed"), th e intended d irections ar e im posed by a random ind icator. Dataare produced in sessions, typically about one hour in durat ion , consisting ofanywhere from a m i n i m u m of five 50-trial r u n s to one or m ore entire series,again depending on operator preference or protocol stru cture. All of the opera-tors are anonymous, uncompensated , adu l t volunteers , none of whom claimextraordin ary abilit ies. No training or incentives are provided, an d i nd iv idua lstyles vary widely from very casual to highly intens e. No attem pts are m a d e tocorrelate performance with any psychological or physiological param eters ,other than those im plicit in the protocol var ia t ions .


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Series Position Effects in Random Event Generator Exper im ents 199The database u n d e r s t udy includes series of 5000, 3000, 2500, an d 1000 tri-als per intention and com bines the results of three dist inct exper im ents , which

differ in term s of run length, series size, and a nu m ber of other optional sec-ondary param eters . However, all follow th e s ame tri-polar protocol and ad -dress the sam e pr imary correlate th e pre-recorded intent ion of the operatorto shift th e m e a n s of the output d is t r ibu t ions in a given direction. All are con-duc t ed u nde r tightly controlled condi t ions , with th e data redundan t ly recordedon-l ine in appropriately labeled c o m p u t e r files and on a paper tape pr in tou t .T h e operators are in the s a m e room as the dev ice d u r i ng its operation, and re-ceive visua l feedback dur ing th e course of each series, as well as su m m a ry sta-t istical feedback at i ts conclu sion . T h u s , for purposes of analysis, as wel l as forth e operator 's conceptual persp ective, each s eries can b e regarded as an i nde-pendent replication of the basic exper iment , standing as a com plete un i t of ef-fort in its ow n right.

DatabaseT h e average m e a n shifts of the approxim ately 840,000 trials per intentioncompounded in this data set are statistically significant in both the high andlow directions. The high efforts produce an overall m e a n c o u n t of 100.026 (z =

3.369, p = 4 x 10 -4), and the low efforts a m ean of 99.984 (z = - 2 . 0 1 6 , p = .022).Th e probab ility of obtainin g this separation of m e a n s of .042 be tween the tw odirections of effort over a database of this size by chance is less than 7 x 10 -5 (z= 3.809). In contrast, the overall baseline mean of 100.013 is not statisticallydifferent from th e expected va lue of 100.000 (p = .096 two-tailed). Since ex-tens ive mach i ne calibrations confirm that the und i s tu rb ed behavior of the de-vice conforms wel l to theoretical chance expectations, with n o indications ofsecular t rends (Nelson, Bradish, & Dobyns , 1989), all compar i sons in thispaper are m ade against theoretical pred iction s.A n u nav o id ab le variable tha t m u s t be carried throu gh this serial posit ion as-ses smen t is the n u m b e r of series performed b y each of the 91 participating op-erators whi ch , for reasons of interest or availability, ranges from one to sixty-f ive. I t should be noted , however, that the i n d i v i dua l operator effect sizes,irrespective of their database sizes, distribute about the shifted m e a n s largelyas one w o u l d expect by chance , with no in dication beyond random f luctuationthat any operators are m ore "effective" than th e others (D u nne , et al, 1988).F or purposes of analysis th e entire database h as been div ided into j u s t five s u b -sets, name ly th e c o m p o u n d s of all first, all second, all th i rd , and all fourth se-ries, and all series n u m b e r e d five an d higher, henceforth denoted b y "5+", ass u m m a r i z e d in Table 1. Note that a l though the last subse t w as produced byonly 21 "prolific" operators, i t cons titu tes 280 series or 54% of the total data-base. It is t h u s possible to construct a m ore balanced set of data consist ing ofthe (1, 2, 3, 4, 5+) series resul t s of these prolific operators alone, for our firstat tempt to assess any possib le series order effects.


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200 B. J. D u n n e , Y. H. D obyns , R. G. J ah n , and R . D. NelsonTABL E 1

Distr ibut ion of Operators over Series N u m b e rSeries No. No. of Operators (% )

1 912 683 584 255678910

( 2120175+ 151313>10 J 12

(100%)(75%)(64%)(27%)(23%)(22%)(19%)(16%)(14%)(14%)(13%)

Prolific Operator ResultsFigure 1 displays the effect sizes for all the tripolar efforts of these 21 prolif-ic operators as a function of series n u m b e r 1 th rough 5+. The combined effectsizes of all of their data are indicated at the extreme right of the graph. Errorbars are 1.65 C T ( p = .05, on e-tailed) for the high-and low-effort data, and 1.96 a

(two-tailed) for the basel ine data. In the high efforts, a highly significant posi-t ive effect in the first series is followed b y a sharp decl ine to negat ive valu es inseries 2, 3, and 4, after which th e positive trend is recovered in the fifth seriesand beyond . The low efforts show a sl ightly different pattern, with first an dsecond series effects significant in the intended direction followed by a sharpreversal to an opposite effect in the third series. The data then revert to the in-tended direction in the fourth series an d beyond . The high-low differences inthese d ata reflect the com bined negative results of both intentions in the thirdseries to produ ce a distinct reversal in the positive effects established in all theother series, w here the separations betw een the high and low values are consis-tent with th e operators' directions of effort. Finally, the baselines interspersedwith these intent ional efforts show no statistical evidence of such a pattern.These series posit ion patterns can be su bm itted to regression analysis to de-term ine the statistical significance of the observed t rends. F or exam ple, th equadrat ic te rms of the regressions provide indications of the degree of curva-ture in the series sequences . Using an appropriate error term that i nc lud es m ea-su rem ent un certainty for the i nd iv idua l points , these coefficients can then b econv erted to standard z-scores, noted on the graphs as Z2. In the high-going ef-forts, th e one-tailed probability of the quadratic coefficient is 4x10

-4, attestingto a signif icant U-shaped trend; in the low efforts, despite th e str iking reversalof effect in the third series, the curv ature is actually non-s igni f icant (p = .290).Th e high-low d ifference cu rva t u r e is signif icant wi th a probab ility of .004, dr i -ven p r im ar i ly by the high- in tent ion results. There is no signif icant cu rva t u r e in


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Series Position Effects in Random Event Generator Experiments 201

Figure 1: Effect Size By Series for 21 Prolific Operators

th e baselines, at a prob ab ility of .604. (All bas eline prob ab ilit ies are calculatedon a two-tailed basis, since excessive excurs ion s in eithe r direction w o u l d con-stitute an anom aly.)Table 2 sum m arizes the effect sizes, or mean shifts , of each of these prolificoperator series subsets in nu mer i ca l form.


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202 B. J. D u n n e , Y. H. Dobyns , R. G. Jahn , and R . D. NelsonT A BLE 2

REG Effect Sizes b y Series Position(364 Series, 21 Prolif ic Operators)

Subset1st Series2nd Series3rd Series4th Series5th Series +A ll

H i gh0.093 *-0.032-0.053-0.0180.035 *0.025 *

Low-0.054 *-0.083 *0.034-0.049 *-0.024 *-0.029 *

d H i - L o0.143*0.051 *-0.0830.0310.059 *0.054 *

Baseline-0.015-0.0350.0120.0430.0080.005

*Signif icant in direction of effort at p < .05

Full Database ResultsAl though the prolific-operator subset provides the m ost balanced b asis forassessing series ord er patterns , it is ins t ruct ive to com p are those results withthose of the fu l l database to assess w hether the observed trend s can be general-ized across unbalanced data cells. Table 3 and Figu re 2 present su ch results forall 522 series com prising th e total REG local diode database, again by seriesorder. Despite th e fact that the i nd iv idua l contr ibut ions from each of the 91operators are qu ite disparate in terms of the nu m ber of series in each subset (cfTable 1), the patterns rem ain generally sim ilar to those s h ow n above. There isa m ore rapid recovery of the effect size in the high efforts, and the third seriesreversal is even more m arked in the low efforts than in the prolific operatorsubse t , bu t the overall t rends , l ike those of th e high-low differences, are essen-tially th e s ame . As before, the basel ines s how n o ev idence of a series order ef-fect. Regression analysis once again yields significant coefficients in the qu a-drat ic com ponen ts of the high efforts ( p = .019) and the high-low differences ( p= .016), w hile the low efforts remain non-s ign i f ican t (p = .154), as do the base-lines (p = .934).The graphs of Figures 3 and 4 present the preceding prolific operator an dtotal database serial position effects in another ins t ruct ive form at, nam ely asprogressions of the cum ulat ive m e a n s . In essence, these displays respond to

T A BLE 3REG Effect Sizes by Series Pos ition

A ll Local Data (522 Series, 91 Operators)Subset1st Series2nd Series-0.0193rd Series4th Series5th Series +A ll

H i g h0.046 *-0.033 *0.0180.0000.035 *0.026 *

Low-0.0090.0150.046-0.033 *-0.024 *-0.016 *

d H i - L o0.055 *0.006

-0.0260.0330.059 *0.042 *

Baseline0.0250.0250.0260.0080.013

* Significant in direction of effort at p < .05


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Series Posit ion Effects in Random Even t Generator Experim en t s 203

Figure 2: Effect Size By Series for All Operators

th e impor tant question: "If the exper im ent had b een term inated at the end ofthe nth series (n = 1, 2, 3 . . . ), wha t w o u l d have been the accumulated effectsize?" The salient in formation here is the rate at which these cumu la t i vem e a n s converge to stable asym ptotic values , and the indication is s o m e w h a tamb iva l en t . On the one h a n d , s o m e fou r to five series suff ice to s u b s u m e m o s tof the pathological variat ions of the early series m e a n s into relatively stable


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204 B. J. D u n n e , Y. H. Dob yn s, R. G. J a h n , and R. D. Nelson

Figure 3: Cumulative Effect Size By Series for 21 Prolific Operators

values , but even these differ somewha t from those u l tim ately achieved afteryet m a n y m o r e series are i nc l uded . These latter, s lower progressions in the cu -m u l a t i v e m e a n s to s ign i f ican t t e rmina l values are largely attributable to a fewextrem ely prolific operators w h o s e effect sizes persist t h rough m a n y tens ofseries ( D u n n e , D o b y n s , & J ah n , 1993).


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Series Position Effects in Rand om Even t Generator Exper imen t s 205

Figure 4: Cumulative Effect Size By Series for All Operators

Operator-Specific PatternsT h r o u g h o u t th e entire laboratory program , m o s t especially the REG class ofexperim en t s , the need to retain comp lemen t a ry perspect ives betw een globalresults averaged across large pools of operators, and operator-specific re su l t s


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206 B. J. D u n n e , Y. H. Dob yns , R. G. Jahn , and R. D. NelsonTAB LE 4RE G Effect Sizes By Experimen t

Experim entOldREGREMREGThouREGA ll

No Trialsper Intention

~300,000177,000360,000837,000

H i g h.035*.005.028*.026*

Low-.019.001-.020 *- .016*

dHi-Lo.054*.004.048*.042*

Baseline.007.018.016.013

* Significant in direction of effort at p < .05that reveal i n d i v i d u a l characteristics, h as been ev iden t . This complementar i tyi s equ al ly im portant in these serial posit ion stud ies. So far w e h av e displayedth e global results of tw o groups of operators, and h ave extracted therefrom th estatistical charac teristics of those representative groups . Next w e turn to indi-v idua l operator data to assess th e degree of variability em bodied there that isbeing s ub su m ed in the global results . For this pu rpose , the in d i v i du a l operatorserial posit ion patterns, per se, are diff icul t to interpret, given th e large errorbars that unavo idab ly at tend the relatively sm all samp le sizes for each seriesm e a n data point . However , th e cumu la t i ve m e a n representations are m uch be t-ter b ehaved and show clear sim ilari t ies to the glob al results in the sam e format .In fact, to good statistical generality, each of the individual operators is foun dto contr ibu te m arginal ly bu t system atically to the global serial position pat-terns, wi t h few if any stark aberrat ions therefrom. In other word s , as is the casefor overall effect sizes, th e global serial position effects appear to be generic,rather than accidental com bin at ions of w idely varying ind ivid u al perfor-mances . I t t h u s seem s reasonab le to expect that s im i la r global effects would b edisplayed by totally di f ferent operator pools. (Cum u la tive e f fect size graphsfor each of the 21 prolific operators are a ssem bled in Dun ne , D obyns , & Jahn(1993), Appendix A .)

Protocol DependenceA s ment ioned earlier, the local REG database is itself a com pos it e of three

dist inct eras of exper im entat ion. Whi l e the basic tripolar protocol rem ainedconstant throughout , th ree major var ia t ions w ere explored over the program'seleven-year his tory , inv olvin g m anipu lation of certain secondary exper im entalparam eters , m o s t notably ru n length an d series size (Nelson & Dobyns , 1991).The first era of investigation, termed OLDREG, consisted of 103 series, m o s tof which required 2500 trials per in tent ion , a l though 18 of the earliest seriesconsisted of 5000 trials per in tent ion , all generated in r u n s of 50 trials each.Th e second era, te rm ed REMREG, consisted of 59 series of 3000 trials per in-tent ion, generated in r u n s of 1000trials each. Th e third era, calledTHOUREG, produced 360 series of 1000 trials per in tent ion , w hich were gen-erated in r u n s of 50, 100, or 1000 trials, depending on operator preference.


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Series Posit ion Effects in Rand om Event Generator Experim ents 207

Figure 5: Effect Size By Experiment Order

Table 4 s u m m a r i z e s th e com posi te effect sizes for each of these databases b yintent ion, and F igu re 5 displays these in graphic fo rm .T h e progression of final scores across these three exper im en t s cou ld be con-strued to display a pattern of initial achievem ent-decline-recovery s o m e w h a ts im i lar to the series position effects described earlier. T h e HI-LO differencepattern has a curvature s ignif icant at p = .014, dr iven b y a "High" cu rva tu re at


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208 B. J. D u n n e , Y. H. Dobyns , R. G. Jah n , and R. D. N elsonTABLE 5REG Rem ote Database Sub sets

Ind icat ing Sequ ence of Operator SeriesSeries No. No. of Operators (% )

1 272 213 194 165678910

1098+5 { 888>10 J 7

(100%)(78%)(70%)(59%)(37%)(33%)(30%)(30%)(30%)(30%)(26%)

p = .033 and a "Low" at p = .100. In con trast, the bas eline trend shows n o evi-dence of curv ature (p = .922). Although identif ication of t rend cu rvatures fromthree-point data is risky, th e possibil i ty of "protocol-position effects" super-imposed on the series position effects cannot be totally ruled out, either as aconfound on the latter, or as evidence of a self-sim ilar character of the effect,as Rhine h ad proposed (Rhine , 1969). Fur the r i llum inat ion of this aspect migh talso follow from searches for position effects at th e levels of experim ental r u n sor even i nd iv idua l trials, bu t in its present architecture, ou r da ta m anagem entsystem does not allow sufficiently convenient access to this level of data struc-ture to m ake such assessm ents feasible.

Remote REG DatabaseAnoth e r large d atabase w as generated on this s ame device u n d e r a "remote"protocol, whe re th e operators were physically separated from th e mach ine b yconsiderable distances, up to several t hou sand miles (Dunne & Jahn , 1992).A ll of the rem ote operators had also served as local operators, and the rem oteprotocol followed th e same tri-polar structure, b u t experientially it certainlyqualifies as a distinct experim ent. For this reason, an independent exam ination

of the remote REG database by series order w as also undertaken. A total of184 remote series, totaling 396,000 trials per intent ion, were produced on thediode device by 27 operators. A ll were generated in 1000-trial r un s , initiated atprearranged t im es by exper im enters w ho w ere bl ind to the sequence of opera-tors' in tent ions . A s in the local database, th e i nd iv idua l operator cont r ibu t ionsw ere som ewh at un ba lanced , with only ten operators produc ing five or m o r e se-ries. The series subsets by operator contr ibut ion are sum m ar ized in Table 5,an d th e effect sizes for the variou s intentions presented in series order in Table6 and Figure 6.These rem ote REG data show effect sizes comparab le to the local data, withs imi la r serial order t rend s, bu t only the high-low differences produce a m argin -


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Series Position Effects in Rand om Even t Generator Experim ents 209T A B L E 6REG Effect Sizes by Series OrderAll Rem ote Data (184 Series, 27 Operators)

Subset1st Series2n d Series3rd Series4th Series5th Series +A ll Data

H i g h0.027-0.0010.009-0.0020.0350.022 *

Low-0.0130.0250.025-0.016-0.0250.001

d H i - L o0.040-0.026-0.0160.0130.0600.032 *

Baseline0.0040.041-0.0000.0130.0070.013

* Significant at p< .05ally significant quadrat ic term ( p = .048). Both th e high and low efforts showslight curv atures in the sam e d i rections as the local data (p = .139 and p = .105,respectively), and the baselines show none at all (p - .730). It is perhaps note-wor thy that the recovery levels in the 5+ subset are actually somewhat largerthan the first series values, in some contrast to the local patterns whe re the re-covery is less com plete. The fact that th e remote operators had had prior expe-rience in the local protocol m ay possibly confound these results s o m e w h a t ,bu t their general consistency with th e local values nevertheless reinforces bothbodies of evidence.

SummaryLike so m u c h of the em pirical data acquired in research on consciousn ess-related anom alies, th e persistent patterns of serial decline and recovery dis-played in the REG databases, both local an d rem ote , are too p r o m i n e n t to beignored, yet too enigm atic and complex to support any obvious s imple inter-pretation. Since no such patterns appear in any of the basel ine data or m a c h i n ecalibration s, it can b e reasonably assumed that these t rends reflect s o m e char-acteristic of the operators, rather than some artifact of machine performance,

and thu s they could conceivably provide some ins igh t into the psychologicaldimens ion of these hu m an/m ach ine in te rac tions . Th is laboratory has tradition -ally eschewed an y assessm en ts of psycho logical or ph ysiological characteris-tics of its operators, for a n u m b e r of reasons. This , along with th e statistical n a-ture of the data and the lack of any system atic record of the operators 'subjective responses to the series order param eter t h u s precludes pur su i t ofspecific psychological correlates at this t ime. However, there is an extensiveliterature on serial position effects associated with learning, memory, andother psych ological/cognit ive processes, as wel l as repeated reference to thisphenomenon in parapsych ological pu blications , some of which is sum m arizedin th e following A ppend ix . The broad sim ilari ties of the patterns in our data tothose reported therein su ggest that some f u n d a m e n t a l attribute of the h u m a npsyche m ay be involved in all of these.On e other in t r iguing, if highly speculative, analogy can b e fo und in a totallydifferent sector, n a m e l y th e u b i q u i t o u s patterns of dam ped per iodic oscilla-


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210 B. J. D u n n e , Y. H. Dobyns , R. G. J a h n , and R . D. Nelson

Figure 6: Effect Size By Series In Remote Data

t ions fo und in a hos t of m echanical an d electrom agnetic physical systems, inn u m e r o u s forms of free w a v e propagat ions , and in var ious biological func-t ions. A ll of these featu re an ini tial m axim u m s ignal excurs ion , followed suc-cessively by a reverse phase, a lesser recovery to the initial polarity, and even -tual stabilization at s o m e steady-state v a l u e . T h e we l l -known requisites forsuch behav io r are an initial i m p u l s e or pertu rb at ion, a restoring force, a natura lresonant f requency, and a d i s sipat ive com ponen t or d am ping agent . Fu r t he r


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Series Position Effects in RandomEven t GeneratorExper imen t s 211scrutiny of experimentssuch as those reported here migh t lead to identif ica-tion of psychological analoguesof these physical variables, thereby enabl ingprogress toward a more quant i ta t ive science of the psyche and its role in thephysical wor l d .

AcknowledgementsThe Princeton Engineering Anomal ies Research program is indebted to theMcDonnel l Foundation, th e Fetzer In st i tu te , Mr. LauranceS. Rockefeller, Mr.D. C. Webster,and the Ohrstrom Foundationfor theircont inued supportof thisresearch. We are also deeply appreciative of the enormous cont r ibu t ions oft ime and en ergy by the var ious operators w h o contributed to this database.

ReferencesD u n n e , B. J., Dob yn s, Y. H., & Ja hn , R. G. (1993). Series Position Effects in Random Even t Gen-

erator E x pe r im e n t s , Technical Note PEAR 93002, Princeton Engineering Anomalies Research,Princeton University, Schoolof Engineering/Applied Science.Du nn e, B. J. & Jahn, R. G. (1992). Experim ents in remote human/machine interact ion, Journal ofScientific Exploration, 6 , 3 1 1 .D u n n e , B. J. & J ah n , R. G. (1993 ). Consciousness, Random ness , and Information, Technical NoteP E A R 93001, Princeton Engineering Anomal ies Research, Princeton Univers i ty, School ofEngineer ing/Applied Science.D u n n e , B. J., Nelson, R. D., D o b y n s , Y. H., & Jahn, R. G. (1988). I n d i v i d ua l Operator C o n t r i b u -t ions in Large Data Base Anomal ies Exper imen ts , Technical Note PEAR 88002, Princeton En-gineer ing Anomalies Research, Princeton Univers i ty, School of Engineer ing/Applied Science.J a h n , R. G., Dobyns, Y. H., & Dunne, B. J. (1991). Count population profiles in engineeringanomalies experiments , Journal of Scientific Exploration, 5 , 2, 205.Jahn , R. G. & Dun n e , B. J. (1987). Margins of Reality: T he Role of C o n s c i o u s n e s s in the PhysicalWorld. San Diego, N ew York, London: Harcourt Brace Jovanovich.J a hn , R. G., Du nne , B. J., & Nelson , R. D. (1987). Engineering anom alies research, Journal of Sci-entific Exploration, 1, 21.Nelson , R. D., Bradish , G. J., & Dobyns, Y. H. (1989). Rand om Even t Generator: Quali f icat ionand Calibration an d Analys i s , Technical Note PEAR 89001, Princeton Engineering A noma l i e sResearch, Princeton Univers i ty , School of Engineer ing/Applied Science.Nelson , R. D. & Dobyns, Y. H. (1991). Analys i s of Variance of REG Experiments: Operator In -tent ion, Secondary Param eters, Database Structure, Technical Note PEAR 91004, PrincetonEngineer ing Anomalies Research, Princeton Univers i ty , School of Engineer ing/Ap plied Sci-ence.Nelson , R. D., D u n n e , B. J., & J a h n , R. G. (1984). An REG Exper iment wi th Large Data Base Ca-pability, III: Operator Related Anomal ie s , Technical Note PEAR 84003, Princeton Engineer ingAnomal ie s Research , Princeton Univers i ty , School of Engineering/Applied Science.Rhine , J. B. (1969).Position effects in Psi test results , Journal of Parapsychology. 33 , 136.Rhine , J. B. & Hu mp h r ey , B. M. (1944). The PK effect with sixty dice per throw, Journal of Pa r a -psychology, 8, 139.

AppendixSerial PositionEffects in the Psychological Literature

A N G E L A T H O M P S O NMany of the earliest accounts of serial position effects occur in pub l i shedworks devoted to memory and learning (Crowder, 1976; Hunte r , 1976). In the


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212 B. J. D u n n e , Y. H. Dob yns , R. G. J a h n , and R . D. Nelsonlate 1800's, Eb b i n gh a u s found t ha t word lists were learned and r emembered se-rially, and that the position of the word s in the list contr ibu ted to their level ofrecall (Hunter , 1976):

A s the person proceeds from on e m e m o r i z i n g trial to the next , cer-tain items in the list are learned more rapidly than others. Thei t ems which are memor ized soones t are those w h i c h occur at thebeginn ing of the list, and the item s w hich are memor ized slowestare those in the m iddle . In other w ords , the readiness with whichan y item is memor i zed depends not only on the item itself bu t alsoon the posit ion it occupies in the list as a w ho le : wh e the r it comesn ear the start of the list, or the m i d d l e , to the end. This is k n o w n asthe 'serial-posit ion effect ' , (p . 135)Crowde r felt that seriality was one of the properties of thought i tself , an dpoints out the orderliness of sequential thought as an explanation for the ef-fect. C o m m e n t i n g on the work of Koriat and Fischhoff (1972), who thoughtthat serial effects h ad the i r origins in semant ic memory , Crowder (1976) con-c luded :

W e have seen serial-posit ion effects extending all the w ay from th emos t t rans ien t measu res o f episodic m e m o r y to the m o s t wel l -learned k nowledge people carry a round with them . (p . 460)He proposed two possible cont r ibu tory effects to such tend encies: the pri-macy an d recency effects:

In j u s t about any learning task in which th e ordering of i t ems is re-qu i red , and in m a n y w h e r e it is not, there is better performance atth e beginning and end of the series than elsewhere , with th e hard-est position occurr ing s o m e w h e r e j u s t b eyond the m idd le . The ad -vantage of the early i tems is called the pr im acy effect and the ad-van tage of the last i tems is called th e recency effect. (p . 445)b u t then w e n t on to admit that whether these prim acy and recency effects arel inked b y a single causa t ive factor still needed to be determ ined :

. . . . th e theoretical analysis of the serial-position effect in a stateof un t i d i nes s that is alm ost em bar rass ing in view of the ext reme re-liability an d pervasiveness of the phenom enon , (p . 477)

More recen t research h as been condu c ted in spatial m e m o r y tasks of prever-b al children (Cornell & Bergs t rom, 1983) an d adu l t h u m a n m e m o r y research(Proctor & Healy, 1987; Ley & Long, 1988;Au d a y , S u l l i van , & Cross, 1988;Penney & Blackwood , 1989;Jahnke , Davi s , & Bower, 1989; Wagner &Pfautz , 1978; Kresner, M e a s o m , & For sman , 1984). These effects have evenbeen noted in n o n - h um a n a n i m a l s tud ies of spatial m e m o r y ( Jahnke , Davis, &Bower , 1989; Wagner & Pfau t z , 1978; Kresner, M e a s o m , & F o r s m a n , 1984;Santiago & Wright, 1984;Wright , Sant iago, & Sands , 1984;Wright , 1985;


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Series Position Effects in Random E ven t Generator Exper imen ts 213Dale, 1987). Serial-position effects have also been em ployed as a m e a n s of in-vestigating and improv ing learning skills in handicapped students (Glidden,Pawlewski , Mar, & Zigm an , 1979; Laufenberg & Scruggs, 1986), with deafs tuden t s (Bonvi l l ian , 1983; Krakow & H anso n , 1985), an d wi th disabled read-er s (Manis & Morrison, 1982). Declines in the product ion of serial-position ef-fects h a v e been noted i n memo ry tasks perform ed by Alzh eim er pat ients(Pepin & Eslinger, 1989), in pat ients wi th brain dam age caused b y solvent in -toxication (Laufenberg & Scruggs, 1986; Stollery & Fl ind t , 1988), and in pa-t ients wi th surgery to the right h ippocampa l region of the brain (Jones-Got-m a n , 1986). Serial position effects have also been generally em ployed as aclinical diagnostic test of m e m o r y funct ion (Frith, 1984; Dinges & White -house , 1985).Burdick and Kelly noted a similar class of non-random occurrences in thestatistical distributions of scoring in parapsychological expe rim en t s , w h i c hthey termed linear and qu adratic trends (Burdick & Kelly, 1977). Th e latter de-scribe th e tendency for scoring to be more extrem e at the ends of the r u n s t h a nin t he midd le ( terminal sal ience) , leading to U-shaped or inverted-U-shapeddis t r ibut ions or scoring. Th e au tho rs r ecommended analysis of variance as aneffective tool to examine these types of trends in statistical data. They notedthat systematic cyclical or periodic t rend s m ay also mer i t attention, suggestingthat techniq u es of autocorrelation be u sed to extract any evidence of such peri-odicity in the scoring.

Rhine and H u m p h r e y , reporting retrospectively on data accumula ted at theD u k e Unive rs i ty Parapsychology Laboratory, discovered an unequa l d i s t r i bu -tion of effects w hich followed a typical t em poral pattern (Rh ine & H u m p h r e y ,1944). They described t rends s imilar to quadra t ic and serial-posi t ion effects,wh ich they termed quarter-decline effects. In a later paper, Rhine noted s o m eof the characteristics of these position effects, defining t hem a s patterns of hitf requency that relate to the s t ructure of the test, an d noted tha t decl ines a n d U-curves were patterns m o s t f requen t ly observed (Rhine , 1969). These seemedmore marked ly demonstrated by adults than by children, and could be foundfrom the trial level up to the experim en tal level.Rhine also observed that the stricter the experimental controls, th e morepronounced were the position effects, be ing mos t preva len t in exper im entswhere a) single su bjects w orked alone and were aw are of their progress as theyrecorded the i r ow n results , or b) tw o people worked together , alternating rolesas subject an d recorder. Persistence of effort th rough long series seemed to em -phas ize the p h e n o m e n o n , an d close preoccupation with th e record sh eet to in-tensify th e effect. Position effects were found both in ESP and PK experi-men t s , and were t ho ug h t to be related to the s u b ject's reaction to the s t ruc tu reof th e test record. For example, spontaneity w as suggested as one relevant fac-tor. A sub jec t ' s first r u n , w here his or her expectations for an ou t come w o u l db e m o s t a m b i gu o u s , m ig h t b e most conduc ive to spon taneous performance .However , as the exper imen t con t inued , associative factors w o u l d take on anincreasing role i n m odu lat ing the subject ' s attitudes and expectancies th rough


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214 B. J. D u n n e , Y. H. Dobyns , R. G. J a h n , and R. D. Nelsonfeedback. Arr iv ing at the last trial cou ld p roduce a l iberating feeling, allowingsufficient spontaneity to re-em erge to elude the pattern association carriedalong to that point .

These observat ions from parapsychology research are consistent wi th f ind-ings in stud ies of v igilance and attention reported in the cogn it iv e science liter-ature, w here declines were f ou n d to relate to expectancy and su bjective proba-bility, signal probabil i ty, instruct ion, and feedback. C o l q u h o u n an d Baddeleyshowed tha t expectancies established during a training session could signifi-cantly in f luence th e course of a vigilance task in t e rms of score decrement(Colquhoun & Bad deley, 1964; Colquhoun & Bad deley, 1967). They found agreater decrement in hits over t ime for observ ers trained with an inappropriate-ly high sign al rate than those trained with a signal appropriate to that actuallyused in the task. Colquhoun suggested that a major part of the decrement ob-served in m a n y vigilance studies m ay be du e to inap propr iate expectancies d e-veloped in the pretask period (Colquhoun , 1975). However, as the subjectmatched h is expectancies with the task signal , recovery could take place.Bevan and Turner examined shift expectancies an d fo und t ha t a shift f rom aposit ive to a negative reinforcem ent, or in the converse , had a greater im pacton vigilance performance than con t inuous or negative reinforcem ent (Bevan& Turner, 1965). (This point m ay have particular relevance to the R EG experi-ment s described in the m ain body of this paper, w here operators receive alter-nating positive an d negative reinforcement as the m achine does its randomwa lk over the course of a run or series.)Serial position effects h ave also attracted the attention of the skeptical com-m un i ty , w i th som ewh at equ ivoca l conc lus ions . F or exam p l e, Girden an d Gird-en (1985) note:In th e m ore recent l i teratur e, d eclines are noted in s o m e studies, s o m e w h a tlike a passing remark , ra ther than th e result of a statistical test. In fact, moreoften than not , especially with a r a n do m - n u m b e r generator, it is noted thatthere w as no decline, which is usua l ly attribu ted to the trial-by-trial feedb ackof in form ation . Apparent ly , n o specific tests of declines have been recentlycarried out , and it is possible th at interest in th e decline effect m ay fu r the r d e-crease and vanish. (p . 138)Notwi th s t and ing this speculation, it is ou r v iew, based on the results report-ed in the bod y of this paper, that serial position effects wil l cont inue to provideimpor tan t indicators regarding the psychological aspects of anomaloushuman / mach i ne interactions, an d should be carefully stud ied accordingly.

Appendix ReferencesAuda y , B. C., Sul l i van , C., & Cross, H. A. (1988). T h e effects of const ra ined rehearsal on j u d g -me n t s of t empora l order, Bulletin of th e P s y c h o n o m i c Society, 26, 548.B e va n , W . & Turner , E. D. (1965). Vigi lance performance wi th a qual i tat ive sh i f t in reinforcers,Journal of Experim ental Psychology, 70. 83.Bonv i l l i an , J. D. (1983). Effects of signabil i ty an d imagery on word recall of deaf an d hearing s tu -dents , Perceptual and Motor Skills , 56 , 775.


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Series Position Effects in Random E ven t Generator Experiments 215Burd ick , D. S. and Kelly, E. F. (1977). Statistical Methods in Parapsychological Research, in B. B.Wo lm a n (Ed.) Handbook of Parapsychology, New York: Van Nost rand .Co lq u h o u n , W. P. (1975). Evaluat ion of auditory, v i sua l and dua l -mode displays fo r prolongedsonar m oni tor ing in repeated sessions , H u m a n Factors, 17 , 425.Co lq u h o u n , W. P . & Badd eley, A. D. (1964). Role of pretest expectancy in vigilance sonar m o n i -toring in repeated sessions, H u m a n F a c to rs , 68 , 156.Co lq u h o u n , W . P. & Baddeley, A. D. (1967). I n f l uence of signal probabil i ty du r ing pretraining onvigilance dec remen t , Journal of Experim ental P syc hol ogy, 73, 153.Cornell, E. H. & Bergstrom , L. I. (1983). Serial-position effects in i n f an t s ' recognition m em or y ,Mem ory and C ogni t ion, 11, 494.Crowder, R. G. (1976). P rinciples of Learning and M e m o r y . Hillside, NJ: John Whiley.Dale, R. H. (1987). Sim ilarities be tween h u m a n an d a n im a l spatial m em ory: I tem an d order infor-mat ion , A n im a l Learning and Behavior, 15 , 293.Dinges, D. F., & W hitehou se, W. G. (1985). A dua l probe recogni t ion memory task for use d u r i n gsus ta ined operations, Behavior, R e s e a r c h Methods, Ins trum ents and C om pute rs , 17 , 656.Fri th , C. D. (1984). The effects of i n t r avenou s diazepam and hyosc ine upon th e h u m a n m em or y ,Q uarterly Journal of Experim ental P sychology H u m a n Experim ental P syc hol ogy, 36 , 133.Girden E. & Girden , E. (1985). Ps ychokin esis: Fifty years af terward, in P. Kur tz (Ed.) A Skeptic'sHandbook of P arapsyc hol ogy, Buffalo , NY: Pro me t he u s Books.Glidden, L. M., P aw lew ski, C. E., Mar, H., & Zigm an, W . (1979). Extended recency effect extend-ed : Blocking, presentation m o d e and retention interval , A m e r ic a n Journal of Mental Deficien-cy, 84, 74.Hunte r , I. M. L. (1976) M e m o r y . London , England : P engu in .Jahnke , J. C., Davis , S. T, & Bower, R. E. (1989). Posit ion and order information in recognitionmemory , Journal of Experim ental P sychology, Learning, M e m o r y an d C ogni t ion, 15 , 859.Jones-Gotman, M. (1986). Right h ippo c a m pa l excision impai rs learning and recall of a list of ab-stract designs , Neuropsychologia, 24, 659.Koriat, A . & Fischhoff , B . (1972). W h a t day is today? A n inqu iry in to th e process of t im e orienta-tion, M e m ory and C ogni t ion, 2, 201.Krakow, R. A,, & H a n s o n , V. L. (1985). Deaf signers and serial recall in the v i sua l modal i ty:Memory fo r signs, finger-spelling and pr int , Mem ory and C ogni t ion, 13 , 265.Kresner, R. P., Measom, M. O., & Forsman , S. L. (1984). Serial-position curves in rats: Orderm em or y for episodic spatial events , Anim al Learning and Behavior, 12 , 378.Laufenberg, R. & Scru ggs, T. E. (1986). Effects of a transform ational m nem onic strategy to facil-itate a digit span recall by mi ld ly handicapped students, Psychological Reports , 58, 811.Ley, R. & Long, K . (1988). A distractor-free test of recognition and false recognition, Bulletin ofth e P s y c ho no m i c Society, 25, 411.Manis , R. F. & Morrison, F. J. (1982). Processing of identity an d position inform ation in norm alan d disabled readers, Journal of Experim ental Child P syc hol ogy, 33, 74.Penney, C. G. & Blackwood, P. A. (1989). Recall mode an d recency in im m ediate serial recalls :Com pute r use rs beware, Bulletin of th e P s y c h on o m i c Society, 27, 545.Pepin, E. P. & Eslinger, P. J. (1989). Verbal memory decline in A l z h e i m e r ' s disease: A m u l t i -

process deficit, Neurology, 39 , 1477.Proctor, R. W. & Healy, A. F. (1987). Task-specific serial position effects in com parison of m u l t i -letter strings, P erception and Psychophysics, 42 , 180.Rhine , J. B. (1969). Posit ion effects in Psi test resul t s , Journal of Parapsychology, 33 , 136.Rhine , J. B. & H u m ph r e y , B. M. (1944). The PK effect with s ixty dice per th row , Journal of P a r a -psychology, 8, 139.Santiago, H. C. & W right, A. A. (1984). Pigeon me mo ry : Same/dif ferent concept learning, serialprobe recognition acquis i t ion , an d probe delay effects on the serial-position f unc t ion , Journalof Experim ental Ps ychology Anim al Behavior P r o c e s s e s , 10 , 498.Stollery, B. T. & Fl indt , M. L. (1988). M em or y sequelae of solvent intoxication, ScandinavianJournal of Work, Environm ent an d Health, 14, 45.Wagner, A. R. & Pfau tz , P. L. (1978). A bow ed serial-position func t ion in hab i tua t ion of sequen-tial s t im u l i , A n im a l Learning and Behavior, 6, 395.Wright, A. A. (1985). Memory processing of serial lists by pigeons , m onk eys an d people, Science,229, 287.Wright, A. A., Santiago, H. C., & Sands , S. F. (1984). Monkey m e m o r y : Same/dif ferent concep tlearning, serial probe acquis i t ion an d probe delay effects, Journal of Experim ental P sycholo-g y, 10,513.

brenda j. dunne et al- series position effects in random event generator experiments

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