The purpose of this study was to examine the effects of flicker stimulation of varying frequencies upon the EEG patterns under 3 different conditions: eyes closed (EC) and eyes opened (EO) both in resting state and mental calculation with eyes closed (MC).
10 male and 10 female adults were individually introduced, into a sound-proofed and electrically shielded, dark room where the EEG was recorded monopolarly from the frontal, temporal, vertex, and occipital needle electrodes with reference to the right earlobe and was simultaneously frequency-analyzed by a Walter-type analyzer which permitted 10-sec epoch analyses of the occipital EEG through 10 band pass filters (Table 1). Flickering lights of varying frequencies (Table 1) were presented under the 3 different conditions (EC, MC and EO). For 5 Ss the procedure was repeated 3 times with an interval of about a week or more in order to assess the reliability of the cortical response (EEG) patterns.
The results were based on the cortical responses in terms of the integrated values per 10 sec expressed by analyzer pen deflection in mm through the 5 band pass filters covering alpha and beta ranges. The cortical responses in integrated values were highest under EC and lowest under EO, indicating a greater blocking effect under EO than under MC; in addition, in accordance with Motokizawa (1963), not only alpha but also beta responses were suppressed under EO. Fig. 2 indicates highly constant EEG patterns (band spectra) in 3 replications. Moreover, intrasubject correlations in band spectra were considerably high, especially under EC (mean r_s=0.80). When the Ss were classified into 3 types (R, P and M) of the alpha response following Walter (1953), the obtained distribution was about identical to his findings.
Photic driving has been variously defined by different authors. First, it was defined in terms of cortical responses under photic intermittent stimulation, and second in terms of the difference between cortical responses under the stimulation and those under no such stimulation. This second definition is evidently superior to the first since spontaneous responses are excluded but it still neglects nonspecific arousal effects (alpha blocking in alpha ranges) of the photic stimulation itself. Thus the third definition is cortical responses under frequency-specific stimulation minus those due to non-frequency specific stimulation. In order to obtain the latter measure, the present study utilized the lowest response of the band (one of the 5 frequency ranges) under stimulation of flickering lights which were not included in that band.
Band spectra under flicker and non-flicker conditions are shown in Figs. 4, 5 and 6 and the amount of photic driving in 3 different definitions in Table 3 and that in the 3rd definition in Fig. 6. Photic driving 1 or definition 1 was larger under both EC and MC than under EO and the difference between the first two conditions was negligible. Photic driving 2 was the least under EC for the 3 alpha ranges (bands) and a negative correlation was found between photic driving 2 and either spontaneous alpha responses under EC or the alpha increments from EO to EC conditions. Photic driving 3 was closer in trends to the first definition and mental activity was not effective. The results were explained in terms of the interactions between facilitative and inhibitory effects on alpha responsiveness in addition to its possible upper and lower limits.
As was expected, photic driving was quite different between the alpha and beta responses, which would probably indicate different underlying mechanisms.

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This paper is the first part of the report on an experiment with the three-person interpersonal choice game, conducted for the purpose of obtaining basic information concerning the dynamic aspects of the three-person game-playing processes, including the formation and the disintegration of coalitions.
The rules of this game, symmetric over its three players, ask each of them simultaneously to choose on every trial between the two players besides himself (under conditions A and A₊) or among the three players including himself (under conditions B, B₊, C, C₊). In this first report only the results with the conditions A and A₊ are reported. The payoff to players (in game points only, no monetary payment given) on each trial consists of three components: the gain for being chosen, the cost for making a choice, and the special bonus for the two players who choose each other (given only under conditions with the plus sign). For details, see Tables 1 and 2.
The Ss were college students, 7 triads each for conditions A and A₊, and they were encouraged to make as many points as possible through instruction. Each triad was run for more than 210 trials. The choices made by the three players were fed back to them on every trial.
In order to interpret the results we need to know the good strategies for playing this game, but the goodness of a strategy obviously depends on the motive each S may entertain for playing this game. We considered as the likely alternatives the motive of maximizing one's own gain and the motive of maximizing the difference in gain between his and the others'. Also, we thought it important to distinguish the span of strategies, between long-range strategies and short-range ones. As for the long-range strategy, it is undoubtedly recommendable under both motives to form a stable mutual choice relation (coalition) and to maintain it, although condition A₊ supplies a stronger incentive to this strategy than A. As for the short-range strategies only the motive of maximizing the difference practically counts, and it provides an incentive to desert the coalition partner by shifting one's choice. The changes in the gain and the difference following defection and the expected immediate retaliation (the former coalition partner also shifting his choice) are depicted in Fig. 2, showing that condition A₊ also provides a stronger incentive for defection. As a result, it is expected that the rate of coalition formation and disintegration will both be greater under condition A₊ than under A, and the result confirmed this expectation.
Other major results, obtained mostly by applying the analysis of covariation, a newly developed data analysis technique by Toda, are as follows: The longer a coalition is maintained, the greater the probability of its further continuation. The triad differences are large, but are fairly well represented by setting up four triad categories, α_I, α_II, β_I and β_II. Among triads belonging to α_I, α_II categories, the long range strategies appear popular, and β_II triads show a definite favor for the short range ones. The effect of the condition difference upon the overall behavior of triads is far less significant than that of the difference in categories, or strategies employed by each triad.

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