侧脑室注射东莨菪碱对条件反射及对海马神经元自发放电的影响

本工作采用食物性运动,条件反射方法和慢性微电极记录技术。条件反射实验在9只兔上进行,海马自发放电的实验在22只兔上进行。在9次实验中,30μg的东莨菪碱注入一侧脑室后,条件反射均受到抑制,而吃食则不受影响。注射剂量为45μg时,注射后3—5分,条件反射完全消失,而吃食行为在了次实验中不受影响,在2次实验中稍有减弱,注射后20分钟左右条件反射开始恢复;侧脑室注射40μg的东莨菪碱后,海马神经元的自发活动无明显改变。文中并对抗胆碱药作用于海马抑制条件反射的可能方式进行了讨论。     

汉语语义记忆提取的初步研究

对汉语语义记忆的提取进行了两个实验。实验1是自由联想实验,从十三个句子中选出二十三个词作为刺激词。结果表明,以两词间所保持的常识关系来定义的语义距离,对预测自由联想的作业是有效的。实验2采用反应时技术,对真假命题判断及信息提取的时间进行了考查。实验结果与A.M.Collins等人的结果一致,说明了存储于网络不同水平上的句子其提取时间不同这一事实。结果还表明,在信息提取阶段上,汉字字形的作用不是一个重要的因素。     

On the discriminability of stimulus duration.

The performance of pigeons trained to detect differences in the duration of stimuli was analysed using a matching model of signal detection. Two white stimuli, S1 and S2, differing in duration, were arranged with equal probability on the center key of a three-key chamber. S1 was systematically varied from 5 seconds to 25 seconds while S2 remained constant at 30 seconds. On completion of the center-key stimulus, a peck on the center key turned on the two red side keys. A left-key response was "correct" when S1 had been in effect on the center key and a right-key response was "correct" on S2 trials. A correct response produced a 3-second magazine light accompanied intermittently by food. Incorrect responses produced 3-second blackouts. Detection performance was measured under two procedures. In the first, the obtained reinforcement ratio was uncontrolled by allowing the number of food reinforcements obtained for correct left- and right-key responses to vary as the stimuli were changed. In the second procedure, the presentation of food reinforcement was controlled by holding the obtained reinforcement ratio constant. Discriminability changed as a function of stimulus differences under both procedures. No such trend was found in response bias.     

An investigation of peak shift and behavioral contrast for autoshaped and operant behavior.

Instrumental treadle press and nonreinforced key peck responses were monitored during discrimination training and generalization testing in pigeons on positive and negative reinforcement schedules. In Experiment 1, six pigeons pressed a treadle for food on a multiple variable-interval extinction schedule. In Experiment 2, three pigeons pressed a treadle to avoid shock on a multiple free-operant avoidance extinction schedule. Different color keylights signaled S+ and S- components. Some positive behavioral contrast occurred during discrimination training, but the effect was small. Pecking occurred to the S+ keylight in Experiment 1 but not in Experiment 2. On stimulus generalization tests, all subjects displayed a positive peak shift when pressing the treadle for food or to avoid shock. However, peak shift was not found for nonreinforced "autopecks" on the stimulus key, although an area shift was observed in Experiment 1. This is the first demonstration of peak shift for pigeons pressing treadles and the only reliable demonstration of peak shift when negative reinforcement maintained responding. These results, in combination with previous demonstrations of peak shift for rats pressing levers and pigeons pecking keys, indicate that peak shift is a general by-product of operant discrimination learning, since it occurs across a variety of the organisms, responses, and reinforcers.     

Context dependent changes in the reinforcing strength of schedule-induced drinking.

Previous experiments show that the opportunity to engage in schedule-induced responding is reinforcing. In this experiment, the reinforcing strength of schedule-induced drinking was measured. Four rats were trained on a concurrent-chain schedule. The two terminal links provided food pellets on identical fixed-time schedules. In addition, one terminal link also provided the opportunity to press a button that operated a water dipper. In this link, the rats showed polydipsic drinking. Button-pressing rate for polydipsic drinking was a bitonic function of pellet rate, and it was possible to describe the relationship with a slightly modified version of the matching equation for primary reinforcement. This equation also closely fit the data from other studies. Initial-link response rates, however, did not appear to be influenced by the availability of water in the terminal links. Control conditions suggested that the reinforcing strength of polydipsia was strongly bound to the context provided by periodic food reinforcement.     

Local contrast and maintained generalization.

Pigeons received variable-interval reinforcement for key pecking during presentations of horizontal and vertical line-orientation stimuli, while pecks during five intermediate orientations were extinguished. Lowest peck rates were observed during presentations of negative stimuli adjacent to the positive orientations while peck rate during 45 degrees (the intermediate negative orientation) was relatively high, i.e., there were negative contrast shoulders. When peck rates were manipulated in the positive orientations, peck rate in neithboring orientations changed in the opposite direction. Contrast shoulders faded after prolonged training. A second type of contrast, local contrast, was correlated with similarity of preceding stimulus and different average peck rates during different stages of the discrimination process. The data suggest that sequential local contrast accompanying the formation of a discrimination contributes to the form of generalization gradients. Blough's model of stimulus control predicts the changes in gradient form described here, but may not accurately depict the underlying process responsible for gradient form.     

Gender typing of game choices and qualities of boys' play behavior

Relationships between gender choices and both movement patterns and social behavior were studied in first- and second-grade boys. Three-child, structured play groups were each composed of a boy whose mother saw him as high masculine in play preference on the Games Inventory, one seen as average, and one low masculine. Behaviors rated from videotapes included gender presentation variables, (e.g., leg separation), indicators of dominance and personal comfort (e.g.,range of movements), and indicators of social skill and peer response (e.g., interaction initiations). The low masculine boys were found to be the most feminine in their gender presentation, least dominant and aggressive, and the least socially successful of the boys. The greatest difference was between the low and the high masculine boys. The average masculine boys' scores were generally intermediate,but more similar to the low masculine boys on some variables and more similar to the high masculine boys on others. These conclusions apply to a group interaction play task, but not to an initial noninteractive play task. A secondary study in which girls played with low and average masculine boys is also reported. Here it was found that low masculine boys were generally intermediate between average boys and girls on gender presentation and dominance variables, but lowest of the groups on social interaction variables. The authors appreciate the comments of Peter Bentler and Spencer Thompson on a draft of this paper, the assistance of Laura McCain in running subjects and scoring tapes, and the expertise of Shu-Yeng Wong for computer programming.     

Accessibility of the voicing distinction for learning phonological rules

In three experiments a series of nonsense syllables ending in consonants was presented to adult subjects who had to discover or learn a rule classifying the syllables into two groups. The rule was based either on the voicing of the final consonants or on an arbitrary division of them. Subjects performed better with the voicing than with the arbitrary rule only when there was a straightforward relationship between the voicing rule and the plural formation rule in English or, more generally, when voicing assimilation with an added consonant was involved and attention was focused on the sound and articulation of the syllables. We conclude that the voicing distinction is not ordinarily accessible and that individuals easily learn and use phonological rules involving voicing assimilation because of articulatory constraints on the production of consonant clusters.