Reinstatement of postresponse stimuli prior to reward in delayed-reward discrimination learning by pigeons

Delayed-reward learning in pigeons was examined using a simultaneous red-green visual discrimination task in which the conditions during the delay interval were varied between groups. The nondifferential group received training in which the stimulus present during the 1-min delay was the same following a peck on the correct and incorrect colors. The other three groups received 1-min delay training in which different stimuli occurred in the delay interval following correct and incorrect choices. The differential group received continuous, differential stimuli during the delay. The reinstatement group received the differential stimuli in the 10 sec immediately following the choice and during the last 10 sec of the delay. The reversedcue group was treated in the same way, except that the 10-sec delay stimulus immediately following an incorrect response was also presented for 10 sec prior to reward on correct choices, and the stimulus following a correct response also occurred 10 sec before nonreward on incorrect choices. Nondifferential birds failed to learn the discrimination, while differential and reinstatement birds learned it readily. The reversed-cue birds learned to choose the incorrect stimulus. Differential and reinstatement birds showed no decrement in performance when the delay was increased to 2 min. These findings suggest that similarity of prereward and postresponse delay stimuli controls choice responding in long-delay learning, a finding compatible with both memorial and conditioned reinforcement interpretations.     

Contextual generality of roosttime restlessness in captive American robins (Turdus migratorius)

A series of experiments with captive American robins examined factors affecting roosttime restlessness, that is, the burst of locomotor activity that appears at dusk and is thought to be a correlate of the communal roosting habit of this species. First, the restlessness occurred earlier on cloudy days than on sunny ones, suggesting the importance of illumination level in initiating the activity burst. Second, in studies on social effects, the restlessness was greater when robins were totally isolated than when they had visual-auditory access to conspecifics; indeed, when a small flock of robins was housed together, restlessness at dusk was suppressed completely. Third, the birds were more restless when they could see a human observer than when they could not, implying an interaction of tearfulness with the roosting tendency. Finally, restlessness occurred in a large flight cage as well as in small cages, as long as the birds were not maintained in a flock. In sum, roosttime restlessness appears to be a robust phenomenon that occurs under a wide range of laboratory conditions, but which also can be substantially influenced by numerous environmental variables. Further experimental examination of these variables may advance present understanding of the survival value of communal roosting in this species.     

Distress calling induced by reductions in group size in ducklings reared with conspecifics or imprinting stimuli

Peking ducklings were reared for 1–2 weeks with either 9 or 12 companions, which were either conspecifics or imprinting stimuli (blocks of foam rubber). They were then tested for their tendency to distress call as the number of companions was reduced systematically. Consistent with prior research, ducklings reared with conspecifics modulated their distress calling as a function of both the number of companions with which they were reared and the number of companions with which they were tested. In contrast, ducklings reared with moving imprinting stimuli gave few if any distress calls, regardless of the number of stimuli with which they were reared or tested, as long as at least one imprinting stimulus was present. The difference in responding did not reflect just a lack of attachment to the imprinting stimuli, since when all stimuli were removed these ducklings gave as many distress calls as the ducklings that had all their conspecifics removed. Finally, ducklings reared with stationary imprinting stimuli displayed an erratic pattern of distress calling when the number of test stimuli was manipulated. These latter ducklings appeared to be less strongly imprinted than the ducklings reared with either conspecifics or moving imprinting stimuli. Implications for understanding duckling perception of brood size and thenature of sibling vs. filial imprinting are examined.     

The erasure of reinstated fear

Three experiments investigated the reinstatement of fear to a previously conditioned and extinguished CS as a result of separate presentation of the original US. That reinstatement was found to be sharply attenuated by nonreinforcement of a second fear elicitor between presentations of the US and testing of the CS. This “erasure” of reinstatement depended upon the fear-eliciting power of the intervening stimulus and, under some circumstances, was essentially complete. Moreover, erasure reduced not only the response to the CS but also the extinction it underwent as a result of subsequent nonreinforcement. It is argued that neither the conditioning of background stimuli nor stimulus generalization among explicit CSs provides an adequate account of these reinstatement and erasure results. Rather, they are interpreted in terms of the construction and destruction of a nonassociative representation of the US during conditioning, extinction, reinstatement, and erasure. In that context, some inferences can be made about the rules governing these nonassociative changes and the ways in which they interact with modifications in associations.     

Perception of degraded vocalizations by budgerigars (Melopsittacus undulatus)

Three budgerigars were trained with operant techniques to discriminate examples of species-specific contact calls. Once the birds learned the discrimination among a large set of calls, they were tested with the calls altered in various ways. The birds’ performance on altered calls was compared with performance on normal calls. Results show that the birds could tolerate large spectral and temporal alterations in the calls with little or no decrement in performance. A comparison of the birds’ performance across conditions shows clear evidence of a redundancy in information contained in the calls. The birds were equally adept at discriminating among the calls when given only high-frequency information and when given only low-frequency information. The birds also performed just as well when presented with only the short beginning portions of the calls as they did when presented with somewhat longer portions near the end of the calls. This ability of budgerigars to discriminate among species-specific vocal signals that are highly distorted is reminiscent of the ability of humans to discriminate and recognize highly distorted speech sounds.     

Prolonged exposure to conspecific and predator odors reduces fear reactions to these odors during subsequent prod-shock tests

In Experiment 1, four groups of male rats were given a session as an intruder in either aggressive (i.e., alpha) or nonaggressive colonies of conspecifics and later received either a 2-h exposure to the odors of the alpha colonies or an exposure-control session with the odors of a nonalpha colony. Two additional groups of rats that had been attacked and defeated by alpha residents were later given a 12-h exposure session with alpha-colony odors or nonaipha-control odors. Twenty-four h after the colony-intruder session, all subjects were given a single 6.5-mA shock from a prod with alpha-colony odors present in the bedding of the test chamber. Attacked rats that had been given exposure-control sessions showed significantly less prod burying and greater freezing than nondefeated subjects. This implies that the alpha-colony odors elicited conditioned fear. In contrast, the attacked subjects that had been given a pretest exposure session with alpha-colony odors showed significantly more prod burying and significantly less freezing. This suggests that the alpha-odor exposure resulted in the extinction of fear to these odors. Furthermore, the 12-h exposure to alpha-colony odors was found to be more effective in reducing fear-mediated responses than was the 2-h exposure. In Experiment 2, three groups of rats were exposed to a cat while they were in a protective cage; later they were given a 12-h exposure session with cat odors, a 12-h exposure-control session with no cat odors, or no exposure treatment. Compared with the two control groups, the subjects that were exposed to cat odors showed less freezing during subsequent prod-shock tests in the presence of cat odors, but they did not show prod burying. The reported changes in fear-mediated reactions to the odors of conspecifics and a predator are discussed in terms of both associative and nonassociative processes.     

如何治理新的逃避增值税行为

增值税是我国现行税收体系中的核心税种,历来就是逃避税与反逃避税的主要较量场所.对增值税缴纳中不断翻新的偷逃税手法进行关注并提出治理对策,于国于民有百益而无一害.     

Conspecific individual recognition between starlings after toxicant-induced sickness

After feeding in the presence of a cagemate (Group S, n = 16), food-deprived starlings were intubated with the toxicant methiocarb (Group E, n = 8) or its nontoxic carrier, propylene glycol (Group C, n = 8). During the 4 days after intubation, the birds in Groups E and C were presented on 2 days with the Group S bird that was present during gavage (S+ bird) and on the other 2 days with another Group S bird (S? bird). Group E (but not Group C) birds were more agonistic toward S+ birds than S? birds, fed less in their presence, and were less likely to enter and perch in the same cage quadrant with them. A second experiment suggested that such differential behavior was probably not the result of behaviors exhibited by the S+ birds. Few calls were recorded in either experiment. Although acoustic signals might have been involved, we suggest that the starlings might have used visual cues to recognize individual conspecifics that were present during aversion learning.     

Recognition of moving video images of conspecifics by pigeons: Effects of individuals, static and dynamic motion cues, and movement

Two groups of pigeons were trained with a go/no-go procedure to discriminate video images of conspecifics based on the individuals or else on their actions. Both groups showed rapid acquisition, and the discrimination transferred to new scenes in Experiment 1 and to static scenes in Experiment 2. In Experiment 3, experimentally naive pigeons were trained to discriminate video images of particular birds showing different actions. Transfer to novel scenes, including a new bird and a new motion, revealed the dominance of motion as a cue to discriminate video images. In Experiment 4, the pigeons trained to discriminate video scenes of 2 pigeons showing a variety of activities successfully recognized these stimuli regardless of whether the video was played forward or backward, and transferred the discrimination to still scenes. The findings suggest that pigeons’ discrimination of video images is primarily based on information that is invariant across static and dynamic conditions.     

Social influences on the identification of toxic foods by Norway rats

In the present experiments, a naive “observer” rat first interacted with a “demonstrator” rat previously fed a diet unfamiliar to the observer. The observer then sampled two unfamiliar diets, one of which was the diet its demonstrator had eaten. The observer was then injected with LiCl and, following recovery from toxicosis, was offered a choice between the two diets it sampled prior to toxicosis induction. It was found that: (1) each observer rat formed an aversion to whichever diet its demonstrator had not eaten, (2) effects of demonstrators on aversion learning by observers were present even if there was a 7- or 8-day delay between interaction of a demonstrator and observer and diet sampling by the observer, and (3) observers interacting with 3 demonstrators, each fed a different diet, subsequently exhibited a reduced tendency to form an aversion to each of the diets eaten by their demonstrators. Taken together, the results indicate that information acquired from conspecifics as to the diets they have eaten can play an important role in determining the foods to which otherwise naive rats will learn aversions.     

Sources of age differences in speed of processing

3 experiments were conducted to study developmental change in the speed of cognitive processes. In Experiment 1, subjects ranging in age from 8 to 21 years were tested on a mental rotation task in which they judged whether pairs of letters presented at different orientations were identical or mirror images, and on a name retrieval task in which they judged if pairs of pictures were identical physically or had the same name. Increases with age in the speed of mental rotation and speed of name retrieval were both well described by exponential functions, and the rate of developmental change was comparable for the 2 tasks. Experiment 2 confirmed that age changes in rate of mental rotation are well described by an exponential function. Experiment 3 demonstrated, on a mental rotation task, a perfect correlation across conditions between children's mean response times and adults' mean response times for corresponding conditions. These results are interpreted as indicating that age differences in speed of processing are due, at least in part, to a central limiting mechanism that increases with age.     

The impact of system specifics on systems thinking

Present and future social and ecological challenges are complex both to understand and to attempt to solve. To comprehend the complex systems underlying these issues, students need systems thinking skills. However, in science education, a uniform delineation of systems thinking across contexts has yet to be established. While there seems to be consensus on a number of key skills from a theoretical perspective, it remains uncertain whether it is possible to distinguish levels of systems thinking, and if so, how they would be determined. In this study, we investigated the impact of the specifics of a system on the skills and levels of systems thinking. We administered a 36-item multiple-choice test to 196 Grade 5 and 6 students. For our analysis, we followed a quantitative approach, applying a systems thinking model that incorporates the latest insights on the levels and skills of systems thinking in geography to the context of ecology. By following an Item Response Theory approach, we confirmed a set of systems thinking skills that are necessary to understand complex systems in ecology: identifying system organization, analyzing system behavior, and system modeling. We examined whether individual skill levels can be distinguished to determine whether a system's general principle or system-specific features cause difficulty for students. Our results indicate that system specifics, such as type of relation within ecosystems (e.g., predator–prey), appear to determine the formation of levels. Students struggled most with the difference between basic, direct cause-and-effect relationships and indirect effects. Once they understood the relevance of indirect relationships in moderately complex systems, a further increase in complexity caused little additional difficulty. Accordingly, we suggest that systems thinking should be examined from a variety of perspectives. To promote interdisciplinary learning, a systems thinking model that defines key commonalities across fields while leaving space for system specifics is needed.     

Selective reinstatement of stimulus-outcome associations

In two experiments, the possibility of outcome-selective reinstatement of conditioned responding was examined. Evidence for outcome-selective reinstatement of previously extinguished appetitively conditioned magazine responses by rats was observed in both Pavlovian (Experiment 1) and discriminated instrumental conditioning (Experiment 2) procedures. In both experiments, stimulus-elicited magazine responses occurred more in the presence of a stimulus whose reinforcer was reinstated than they did in the presence of another stimulus whose reinforcer was not reinstated. This effect was observed after both brief and extensive amounts of extinction. Outcome-selective reinstatement of instrumental leverpressing, however, was not observed, although nonselective reinstatement of magazine responding and leverpressing was obtained in Experiment 2. Overall, the data from these studies challenge existing theories of reinstatement, and they provide additional evidence of the importance of outcome-specific processes in the control of learned performance.     

Focus of attention and choice of text modality in multimedia learning

The term ‘modality effect’ in multimedia learning means that students learn better from pictures combined with spoken rather than written text. The most prominent explanations refer to the split attention between visual text reading and picture observation which could affect transfer of information into working memory, maintenance of information in working memory or the effective size of working memory. The assumption of a continuous need for split attention is questionable, however. Learners can keep pictorial information in working memory, when they have seen the picture before, especially if they have higher prior knowledge. Instead of suffering from a permanent split attention, learners frequently show tendencies to simply ignore pictures. This suggests guiding learners towards picture analysis by picture-related text paragraphs. We assume that these paragraphs are associated with stronger modality effects than content-related paragraphs, especially if the pictures are new to learners. These assumptions were tested in an experiment with 120 students learning about volcanism from illustrated text consisting of segments each including a content-related paragraph followed by a picture-related paragraph describing the accompanying visualization. Content-related and picture-related paragraphs were presented as visual or auditory texts leading to 2x2 conditions of text presentation. Picture novelty was manipulated by presenting a picture throughout the whole segment or only when the picture-related paragraph was read. As expected, picture-related paragraphs were associated with stronger modality effects than content-related paragraphs if picture novelty is high. The distinction between different kinds of paragraphs seems to be important for the prediction of modality effects.     

论企业产品的市场竞争与定位

产品策略是市场营销策略的核心,产品策略正确与否,是市场营销成败的关键所在。企业要使自己的产品能够有较高的市场占有率,就要在市场营销活动中准确地运用市场定位策略。市场定位主要有两种形式:潜在市场定位和显在市场定位。     

大专学生英语交际策略的应用特点研究

通过采用实验、观察和访谈的方法,利用交际策略的分类,研究107名非英语专业大专学生在英语学习过程“说”这一输出环节过程中对交际策略使用的频率和效果,分析他们利用交际策略的特点及存在的问题,并对交际策略的课堂教学进行了初步探讨。     

Behavioral momentum and relapse of extinguished operant responding

Previous experiments on behavioral momentum have shown that relative resistance to extinction of operant behavior in the presence of a stimulus depends on the rate of reinforcement associated with that stimulus, even if some of those reinforcers occur independently of the behavior. We present three experiments examining whether the rate of reinforcement in the presence of a stimulus similarly modulates the relative relapse of operant behavior produced by reinstatement, resurgence, and renewal paradigms. During baseline conditions, pigeons responded for food reinforcement on variable-interval 120-sec schedules in alternating periods of exposure to two stimuli arranged by a multiple schedule. Additional response-independent food presentations were also delivered in the presence of one of the multiple-schedule stimuli. Consistent with previous research, baseline response rates were lower in the presence of the stimulus with the added response-independent reinforcement, and relative resistance to extinction was greater in the presence of that stimulus. In addition, following extinction, the relative relapse of responding produced by reinstatement, resurgence, and renewal paradigms was greater in the presence of the stimulus associated with the higher rate of reinforcement. We suggest that a model of extinction from behavioral momentum theory may be useful for understanding these results.     

Prior knowledge moderates instructional effects on conceptual understanding of statistics

This study investigated the effects of different teaching and learning methods for statistics for 2 levels of prior knowledge on cognitive load, propositional knowledge, and conceptual understanding. Teaching methods were whether or not to provide students with propositional information, and learning strategies were self-explaining the learning material and explaining in pairs. The results indicate that prior knowledge facilitates propositional knowledge development and leads to differential effects of teaching and learning methods on conceptual understanding: Only low prior knowledge students profit from additional information in the learning task and/or explaining in pairs. An implication of these findings is that low prior knowledge students should be guided into the subject matter by means of working in pairs on learning tasks that comprise additional information. Once students have developed more knowledge of the subject matter, they should be stimulated to work individually on learning tasks that do not comprise additional information.     

学习策略及其教学

讨论了学习策略意义、学习策略与教法之间的关系和学习策略教学的相关问题,得出掌握学习策略既是学生学会学习、思考的重要保证,也是学生解决学习问题的有效手段和促进其认知发展的重要途径的结论。学习策略与知识基础和认知机制成正相关,具有明显的个体差异性,存在于教学内容之中;教法必须适合学习策略才能取得良好的教学效果,教法研究也必须以学习策略研究为条件才能深化;学习策略教学适宜在知识教学过程中交叉进行。     

Reinstatement-induced recovery of a taste-LiCl association following extinction

Water-deprived rats were given a single exposure to saccharin and LiCl, either paired or unpaired. Half the subjects then received three saccharin-only exposures (extinction) in the training enclosure, followed by a single LiCl-only presentation (unconditioned stimulus reinstatement) 8 days after conditioning. The remaining subjects received six saccharin-only exposures, followed by LiCl reinstatement 13 days after conditioning. In both cases LiCl reinstatement occurred outside the training/test context. Appreciable recovery from extinction was observed after the partial loss of taste aversion obtained with three extinction sessions and the 8-day conditioning-reinstatement interval, but not after the asymptotic loss of taste aversion obtained with six extinction sessions and the 13-day conditioning-reinstatement interval. Conditioned taste aversions appear to be similar to more traditional associations with respect to both extinction and reinstatement-induced recovery from extinction. The results are discussed with reference to the event-memory, contextual-conditioning, and facilitated-retrieval hypotheses of postextinction reinstatement effects.