Human postdiscrimination gradients: The effects of three-stimulus discrimination training

Young adult subjects were trained in a discrimination involving three pure tones varying in pitch, with two positive stimuli and a negative stimulus located midway between the two. Subjects in the control conditions were trained only with the two positive stimuli. Generalization gradients were bimodal in all cases, but for the control subjects, the modes were at the positive stimulus values, while postdiscrimination gradients were displaced away from the negative stimulus toward the extremes of the continuum. Since, with this procedure, the training and test adaptation levels were the same, the observed displacements are difficult to explain in terms of an adaptation-level account of peak shifts. The observed shifts are more consistent with the conditioning-extinction model which assumes interactions between inhibitory and excitatory gradients. However, overall response rates did not reflect the action of summation processes.     

Retrieval of memory in the pigeon by context manipulations

In Experiment 1, 12 pigeons were given eight sessions of VI single stimulus training with a color in a particular context followed by eight sessions of similar training with a line angle in another context. On the next day, half of the subjects were tested for wavelength and angularity generalization in each of the two contexts, a procedure that was thus consistent with training for one dimension and inconsistent for the other. The subjects made significantly more responses to each training stimulus under the consistent context condition, but there was no difference in absolute or relative generalization slopes. In Experiment 2, 12 pigeons were trained as in Experiment 1, but during generalization testing they were exposed to both contexts sequentially. Under the consistent context condition, the subjects responded more to the two training stimuli and yielded sharper absolute and relative wavelength generalization gradients: Under the inconsistent context condition, responding to the training wavelength was substantially disrupted. Thus, under appropriate testing conditions, contextual control over both the amount and the selectivity of responding can be demonstrated.     

Nondifferential training of pigeons retards acquisition of subsequent discriminations involving other stimuli

In Experiment 1, two groups of pigeons (n = 8) were given nondifferential (ND) training with a green keylight and a white vertical line on a dark surround nonsystematically alternated. Two groups (n = 8) received single stimulus (SS) training with the green light only. In Experiment 2, two groups of pigeons (n = 8) were given ND training with vertical and horizontal lines, while two other groups (n = 8) received SS training with only the vertical line. In both experiments, all groups were transferred to a green S+ (VI reinforced) and a red S? (extinguished) transfer problem. In each experiment, one ND and one SS group was tested in the same context as initial training (houselight off) and one ND and one SS group was tested in a changed context (houselight on). In both experiments and in both contexts, the ND groups performed less well on the transfer problem than did the SS groups. There was no evidence of greater control by the context in ND than in SS groups, which suggests that the observed difference in acquisition of the transfer task is not attributable to a purported difference in control by the context under the two conditions. The overall results favor the position that nondifferential training reduces attention to stimuli involved in the original training procedure and that this reduced attention transfers to stimuli subsequently experienced.     

Bilingualism in Southwest Louisiana

Abstract

The utility of signal detection theory as a framework for the interpretation of concept acquisition was studied in three experiments involving preschool children. In the first two experiments, one group was taught an unfamiliar line angle concept with an example sequence containing minimally different, juxtaposed positive and negative examples and the other group was taught the same concept with a sequence of positive examples. In both experiments, preschoolers taught with the sequence containing positive and negative examples correctly identified significantly more transfer items than the positive only group. In the third experiment, one group was taught an unfamiliar line angle concept with consistent wording from example to example. The other group was taught with instructions that changed from example to example. Subjects in the consistent group identified significantly more posttraining test items but did no better during transfer testing. The results are discussed in terms of signal strength and the signal-to-noise ratio of the instructional communication.     

Relative numerosity as a dimension of stimulus control: The peak shift

Pigeons were trained to discriminate between arrays containing equal numbers of two different elements as S+, and arrays which contained more elements of one kind than the other as S?. They were then tested with the full range of the proportions of the two elements. This resulted in behavioral contrast and peak shift, as the pigeons responded more to arrays containing more positive than negative elements than they did to the positive training arrays. These findings were obtained with elements that differed in color (blue vs. red dots) and with elements that differed in orientation (horizontal vs. vertical rectangles). The results indicate that the stimulus control exerted by the derived dimension of relative numerosity involves the same processes as the fundamental dimensions that characterize simple stimulus elements.     

Performance of rhesus monkeys on two-cue problems with cues separated

Relative performance on color and form dimensions during acquisition of two-cue problems by learning-set-sophisticated rhesus monkeys was evaluated with differential reinforcement. Six animals received 24 two-choice problems, each generated from three planometric stimuli, a reference stimulus, an alternate stimulus identical in color but differing in form, and one identical in form but differing in color. The reference stimulus appeared on every trial of a problem and was paired with one or the other alternate on a given trial On half of the problems, the reference stimulus was positive and on the remainder was negative. Acquisition was nearly equivalent on both cue dimensions with positive reference stimuli, but only one dimension was learned with negative reference stimuli. Results were interpreted as unfavorable to attention theory.     

Pre-service teachers' conceptions and beliefs about the role of real-world knowledge in mathematical modelling of school word problems

Recent research has documented that many pupils show a strong tendency to exclude real-world knowledge from their solutions of school arithmetic word problems. In the present study, a test consisting of 14 word problems—half of which were problematic from a realistic point of view—was administered to a large group of students from three different teacher training institutes in Flanders. For each word problem, the student-teachers were first asked to solve the problem themselves, and afterwards to evaluate four different answers given by pupils. The results revealed a strong tendency among student-teachers to exclude real-world knowledge from their own spontaneous solutions of school word problems as well as from their appreciations of the pupils' answers.     

论语义韵的语篇属性

语义韵不是节点词的属性,而是特定语境下语义共现关系所体现的一种语篇属性。语义韵受到一系列态度成分的渲染,呈动态性和功能性。积极（或消极）态度的词汇和表达可渲染、激发积极（或消极）的语篇语义韵,反之语义韵也可使其辐射范围内的成分具有同样的态度色彩。通过语料库数据的抽样统计,文章具体阐述了不同语境中语篇语义韵对“坚持”和“persist”的态度渲染,从而使其具有积极或消极的语义色彩。语义韵作为一种语篇属性,是构建语篇连贯性的重要手段之一。     

Repeated successive contrast in consummatory behavior with repeated shifts in sucrose concentration

Contrast in consummatory behavior was investigated following repeated shifts from 32% to 4% sucrose. In Experiment 1, contrast in licking and in open-field measures of activity occurred following the second and third downshifts. In Experiments 2a and 2b, equivalent contrast effects occurred following the first and second downshifts in sucrose. In Experiment 3, negative contrast remained unabated following nine downshifts in animals shifted between 32% and 4% sucrose on alternate days. Similar results were found for five downshifts in animals shifted every 2 days. In both of these latter conditions, positive contrast occurred over the first few shifts and was then lost as the 32% control group reached asymptote. These data show that repeated negative contrast effects in consummatory behavior are robust and enduring and occur under several different sets of experimental parameters. The results are discussed in terms of reinforcement level and emotional interpretations of contrast effects, and the possibility was suggested that the causal mechanism of contrast changes with repeated shifts.     

The recency effect in pigeons’ long-term memory

Four experiments are reported in which pigeons first learned one wavelength discrimination (green S+, yellow S?) and then the reversal; finally, after various delays, they were tested for wavelength generalization in extinction. In Experiment 1, the two problems were learned in different contexts; testing in Context 1 produced maximal responding to green in only half of the subjects, even when testing was delayed 30 days. In Experiment 2, testing of the subjects repeatedly in both contexts showed good control by each context after a 30-day delay. In Experiment 3, both problems were learned in the same context, and all gradients showed recency, peaking at yellow, even after 30 days. In Experiment 4, the subjects learned a series of reversals in the same context, terminating in yellow, S+, green, S?, and their gradients peaked at yellow, even after a 30-day delay. In Experiments 3 and 4, the gradients became flatter with increasing delays, and they were flatter in Experiment 4 (after three reversals) than in Experiment 3 (after one reversal). The location of the peak was not affected by delay, but only by testing in a context that had been uniquely associated with Problem 1 (Experiments 1 and 2). It is proposed that the location of gradient peaks indicates what is being remembered, whereas the slope of the obtained gradients indicates how well the target memory has been retrieved.     

Transfer of visual identity matching-to-sample in two california sea lions (zalophus californianus)

In order to assess the abilities of two California sea lions to generalize an identity concept, both animals were taught a two-choice, visual matching-to-sample task. We hypothesized that initial identity-matching problems would be learned as conditional (if...then) discriminations but that an identity concept would emerge after training numerous exemplars of identity matching. After training with 15 two-stimulus identity matching-to-sample problems, transfer tests consisting of 15 novel problems were given to the animals. Pass-fail criteria were defined in terms of performance on Trial 1 of each test problem, performance on test trials compared with baseline trials, and performance on four-trial problem blocks. One sea lion passed on the second transfer test and the other passed on the third; both demonstrated successful generalization of an identity concept by all criteria used. A second experiment consisted of presentation of stimuli previously learned in a different context (arbitrary matching-to-sample). Both subjects immediately applied an identity concept to accurately solve these new problems. These tests conclusively demonstrate transfer of an identity matching rule in California sea lions.     

Fading procedure effects on a visual pattern discrimination reversal in the albino rat

Two groups of albino rats were trained on a simultaneous pattern discrimination task, one with a classical procedure in which the discriminanda remained invariant throughout training, and the other with a fading procedure in which the final task was approached through a series of graduated steps. In a subsequent reversal stage, during which the initial positive stimulus became negative and vice versa, each group was subdivided so that half of the subjects in each original group received reversal training with the same procedure as during acquisition and the other half with the other method. Fading procedures yielded a more proficient performance on every occasion, independently of experimental stage or previous learning history. Results are analyzed in terms of favorable conditions offered by the procedure itself and of beneficial influences exerted over subsequent learning.     

谈新世纪版教材对"有理数及其运算"引入的处理

学生初次接触到负数的概念时 ,对理解负数的意义及有理数的运算法则都会产生困难。北师大新世纪版实验教材对解决这些问题的设计思路有这样几个特点 :借助问题情境、从数不够用了的角度引出“负数” ;渗透正负数是“具有相反意义的量”的数学模型的思想 ;从不同的角度表示正负数 ;经过三个层次、借助不同的素材得出正负整数的加法运算法则 ;在应用中体会有理数的作用、熟练有理数的运算 ,以及降低笔算的难度等。这将有助于帮助学生在理解的基础上掌握相关的内容。     

论技能迁移理论在体操教学中的运用

在体操教学和训练中，运动技能迁移现象普遍存在，合理运用一系列手段来促进技能同的积极性迁移，同时防止或减少消极性迁移的影响，以提高体操教学效果。     

Attention shifts during matching-to-sample performance in pigeons

Two pigeons performed a matching-to-sample task in which a color, a line orientation, or both, might appear on the sample. Stimulus control by (attention to) the color and line components of a compound sample was measured when (a) either component might be relevant (i.e., appear as a comparison stimulus on that trial), and (b) when only one component was relevant. Degree of stimulus control by a given component of the compound sample was higher when only it was relevant than when either component might be relevant. Because the matching-to-sample task separated sample inspection from response choice, interpretation of the results in terms of response competition was ruled out. Because the training procedure led to shifts in stimulus control by the components of the compound sample, explanation of previous matching-to-sample results in terms of reduced perceptual clarity of compound samples was also ruled out. Thus, variations in stimulus control by components of the compound sample were interpreted as showing shifts in attention to the components of the compound sample.     

Training in phonemic segmentation: The effects of visual support

Two experimental studies examined the effects of different types of phonemic segmentation training on phonemic segmentation, reading and spelling. Children with learning disabilities, who were weak in phonemic segmentation, were trained with the use of diagrams and alphabet letters, with alphabet letters only, or with no visual support at all (the control condition). For this purpose three computer-assisted training programs were developed. In the first experiment, 48 children were assigned to one of the three programs. The training period lasted five weeks. Although in each training program the children improved their phonemic segmentation skill, there were no significant differences among the three training programs. This result may have been influenced by the different types of feedback that were provided in the three training programs. In a second experiment, therefore, these differences in feedback were eliminated and 49 different children were trained with the same three programs. The results of this experiment, however, were the same as those of the first experiment. The finding that visual support had no beneficial effects could therefore not be attributed to differences in explicit feedback. It was concluded that with these children, in contrast to preschoolers, phonemic segmentation training using visual support does not have any advantage over auditory training alone. The results of this study indicate that preschoolers and children with reading and spelling problems cannot be treated in the same way. It underlines the importance of further examination of the problems that poor readers and poor spellers encounter in grasping the structure of spoken language.     

The Role of Initial Learning,Problem Features,Prior Knowledge,and Pattern Recognition on Transfer Success

The purpose of this study was to demonstrate that transfer ability (positive and negative) varies depending on the nature of the problems, using the knowledge transfer matrix, as well as being dependent on the individual differences of the learner. A total of 178 participants from the United States and New Zealand completed measures of prior knowledge, pattern recognition, a positive transfer problem, and a negative transfer problem. Nearly 11% of participants could not successfully solve the base problem after the initial learning phase. The problem condition was a significant predictor of positive transfer success, while no significant differences were found for negative transfer, although, there was ample evidence of negative transfer. Furthermore, prior knowledge was only a significant predictor for problems in which the structural features between the problems were different. Future directions are discussed in regard to the initial learning phase, differences in transfer success, and the need for measures of negative transfer.     

Learning in honeybees as a function of amount of reward: Tests of the equal-asymptote assumption

In Experiments 1 and 2, honeybee foragers visiting the laboratory were fed on targets of two different colors, one containing 5 μl and the other containing 20 μl of 50% sucrose solution. The targets were presented singly in quasi-random sequences on the training visits, after which preference was measured in an unrewarded choice test. In Experiment 1, 16 differentially rewarded training trials with each color were followed by the same number of trials with the color-amount relation reversed; no preference for either color was found in the subsequent choice test. In Experiment 2, 20 differentially rewarded training trials with each color—enough to produce a clear preference for the 20-μl color when given directly after pretraining—were given after 10 feedings to repletion on each color that were calculated to generate near-asymptotic associative strength; no preference for either color was found in the subsequent choice test. In Experiment 3, there were 12 feedings to repletion on one color and, on the other, 12 feedings to repletion followed by 15 trials with a small (5 μl) reward; no preference was found in a subsequent choice test. The results of all three experiments support a nonrepresentational interpretation of the role of amount of reward in the learning of honeybees.     

Sample and comparison location as factors in matching acquisition,transfer, and acquired equivalence

Pigeons learned symbolic matching with samples appearing equally often on left and right keys. For a location-relevant group, the reinforced comparison choice for each sample reversed across sample locations; for a location-irrelevant group, the reinforced choices were the same. Consistent with the hypothesis that samples at different locations are functionally different for pigeons, Experiment 1 showed that matching acquisition was comparable in these two groups. Nevertheless, the location-irrelevant group eventually ignored sample location, given that their performances subsequently transferred to a novel (center-key) sample location. This transfer was not simply due to sample familiarity at different training locations; rather, it required that left- and right-key samples occasion the same reinforced choices in training. Acquired equivalence between those samples was then assessed in Experiment 2. The location-irrelevant group showed the predicted equivalence effects, but the location-relevant group did not—in fact, its results were the opposite of those predicted by equivalence. Their results indicate that the functional comparison stimuli are also defined in terms of their locations.