Some developmental processes of timing behavior have been observed as the modification of a series of operant responses and some other collateral responses under several temporal reinforcement schedules, partic-ulary under DRL and DRO schedules (2, 7, 11, 12).
The present study was designed to investigate such processes of timing behavior under the mult FR DRL and the mult FR DRO schedules, respectively. the Ss were 16 male rats of the in-bred Wister strain. They were experimentally naive and approximately 150 days old at the start of the experiment, weighing from 225g with a mean of 253g. After a feeding schedule of 7 days in which food intake was limited to maintain their body weights at about 85% of that in the ad-lib feeding condition, rats were adapted to a standard Skinner box having a response bar and a food tray, within a sound-attenuating room. The next day they were shaped to barpress for a 45mg food pellet for every bar pressing, and trained on a typical CRF schedule for the following 2 days. Thereafter, they were divided into two homogeneous groups of 8 rats. One group was trained with mult FR 5 DRL 8, and the other with mult FR 5 DRO 8. In these procedures, every session was composed of the same 3 replications having an FR component of 3 min, a TO of lmin, a DRL or DRO of 7 min, and a TO of 1 min, respectively. Therefore, every session time was 35min. The turning of a signal lamp and the presenting of a tone were used as the discriminative stimuli between the FR component and the DRL or the DRO component. The following day, each group was divided again into two homogeneous subgroups; the mult FR 5 DRL 8 group was divided into the mult FR 10 DRL 8 and the mult FR 10 DRL 20 groups, the mult FR 5 DRO 8 group into the mult FR 10 DRO 8 and the mult FR 10 DRO 20 groups. The training sessions for these four groups were continued once a day for 30 consecutive days.
The main findings were as follows. The number of responses in each FR component, was gradually increased through the training sessions, but without significant group differences (Fig. 1). The distribution of pause time after the reinforced responses in FR 10 components did not show very many distinctive differences between groups or training sessions (Fig. 2). Fig. 3 indicates the number of responses in the DRL or the DRO components. The differences between groups were not so clear, although all groups decreased their responses with the lapse of the training course. The number of reinforced responses in the DRL or the DRO components was differed significantly in DRL or DRO time used, in the training sessions, and also in the reinforcement schedules applied. Furthermore, some interactions were found (Fig. 4). Fig. 5 and Fig. 6 show the IRT distributions obtained by the most typical individuals in the DRL and the DRO components. According to the training sessions carried out, the distributions of post S^R intervals in DRO 8 and DRO 20 changed gradually to a more suitable direction for those reinforcement schedules (Fig. 7). The differences and the similarities of timing behavior between DRL and DRO schedules were discussed, and some advantages of experiments using the mult schedules to investigate timing behavior were suggested.

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Keio University Pigeons were monocularly trained on an interdimensional excitatory discrimination in which a tilted line stimulus was S^D, and an interdimensional inhibitory discrimination in which a tilted line stimulus was S^Δ. The mirror image reversal effect was observed after the excitatory training (Fig. 1). The mirror image reversal effect in inhibitory dimensional control was obtained by a resistance-to-reinforcement procedure (Fig. 3), but not by a resistanceto-extinction procedure (Fig. 2). The excitatory generalization gradients showed a bimodal shape with peaks at S^D and its mirror image, however, the inhibitory generalization gradients did not clearly show a W-shape with minima at S^Δ and its mirror image.

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幼体期における母-子分離による社会的隔離の結果, 多くの種について幼体のその後の行動に顕著な影響を与えることは, これまでの数多くの実験で証明されてきたが, 特に霊長類において, その影響は著しいように思われる。
隔離により生じる主要な行動障害として順位成立の不安定性 (4, 5), 性行動および養育行動などにみられる不適切性 (1, 3, 8, 9), といったような社会的行動の逸脱があげられる。特に雄ザルの性行動はしばしば統制のとれないものであったことから, 性行動に関しては雌よりも雄にとって幼体期における社会的経験が重要であることを示している。一方, 養育行動に関しては, 野生ザルと比較して隔離飼育雌ザルが養育行動の基本的パターンで適切さを欠くことが多いうえ, こうした雌ザルに育てられた幼体の社会的行動もまた障害を示した (1) 。雌ザルにおけるこの養育行動の発現不全は, 雄ザルにおける性行動の不適切さと対応するものであり, 性により隔離飼育個体の受ける影響の種が異なってくることを示している。
このように初期の社会的隔離の影響は多大であり, 幼体の発達過程における母ザルの積極的役割とともに (2), 種々の社会的経験あるいは社会的学習の重要性が指適されてきた (5) 。
しかしながら, 隔離飼育個体の長期にわたる発達過程において社会的な行動障害がどのような変化を示してくるかの実験は数少なく, わずかに隔離飼育個体と比較的若い正常飼育個体との出合せにより, 隔離飼育個体の社会的行動が改善されたという報告があるにすぎない (7, 10, 11) 。
本実験では母ザルからの隔離時期が異なる2群, すなわち早期隔離群と後期隔離群をそれぞれ生後1年目に集団生活させることにより, 隔離飼育個体の社会的関係の成立過程がいかなるものであり, そうした社会化の過程で隔離飼育個体に特有な社会的欠損がどのような変容を示してくるかを検討した。
早期および後期隔離群における社会的関係の成立過程について, 更に社会化の過程における行動変容について検討した結果, 次のような結果が得られた。
1) 順位成立過程に関しては, 早期隔離群は不安定であり, F, 1という条件下で逆転を示したが, 後期隔離群は成立も早く, かつ安定性を示した。この相違は両群の成育条件における経験の関与性の有無および情動的安定性に求められる。
2) 長期の集団生活の結果, 両群ともにdominant behaviorは減少し, 各個体の行動は平均化すると同時に, 高次のintimate behaviorが発現し社会性の高まりを示してきた。この社会性の高まりは, 隔離時期よりむしろ集団内における個体の順位と高い相関を不した。
3) SUOMI, S.J.らは隔離ザルの社会性を高めるためには, 比較的年令の若い正常飼育ザルとの出合せが効果的であるとしているが, 必ずしも若い正常個体である必要はないように思われる。
4) 順位とenvironmental contactとの間には高い相関が認められ, 生活環境へ働らきかけることの多い幼体ザルは, 順位も高くなるという予測が可能であるように思われる。

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