General and specific factors in the intersensory transfer of form.
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In most response sequences auxiliary responses stop occurring as training increases. Auxiliary responses are precurrent responses that increase the likelihood of reinforcement for subsequent responding, are not required by the programmed contingencies, and occur in situations in which transfer of stimulus control is not prevented. For example, when someone is learning to solve arithmetic problems, some steps, such as writing down intermediate calculations, are skipped as training increases. A paired-associates task was used to investigate the decrease of auxiliary response, in which participants had to learn the second member (arbitrary characters) of each pair upon being presented with the first member (different shapes), and could look up an auxiliary screen (auxiliary response) in order to do so. Task complexity was varied by changing the average programmed frequency of reinforcement for individual responses (Experiment 1) and response sequences (Experiment 3), the programmed probability of reinforcement for responses given a position (PPRPos) with a fixed (Experiment 2) or variable number of associated pairs (Experiment 4), and the programmed probability of reinforcement for responses given a shape with fixed (Experiment 5) or variable (Experiment 6) number of characters per shape. Increases in these variables produced systematic decreases in the duration of auxiliary behavior necessary to learn the task. These results suggest that some aspects of task complexity can be measured based upon the quantification of the programmed contingencies of reinforcement.
Pigeons were trained on a modified three-key matching-to-sample procedure, in which only one comparison key (rather than two) was lighted after an observing response to the center-key standard. Pecks on keys of matching comparison hues were reinforced. When non-matching hues appeared as the initially lighted comparisons, the nonmatching hue terminated and the matching hue appeared on the other side key only if the pigeon did not peck the nonmatching comparison for 4.8 sec. Pecks to the nonmatching hue reset the 4.8-sec delay interval. Three hues were used during acquisition. During transfer tests, two novel hues were substituted individually or together for one or two of the training hues. Latencies to the novel side-key hue were shortest when a novel matching hue appeared as the standard on the center key, and were essentially identical to baseline matching latencies. In contrast, when a novel hue appeared as either a standard or comparison in a nonmatching combination, latencies increased with increasing separation between the noevel hue and the nonmatching hue. These transfer data demonstrate the concept of hue matching.
We investigated the effects of histidine on scopolamine-induced learning deficits in the elevated plus-maze test in mice. In this test, transfer latency (TL), the time mice took to move from the open arm to the enclosed arm, was used as an index of learning and memory. Intraperitoneal administration of scopolamine (0.5 mg/kg) prolonged the TL on day 2 compared with that in the saline-treated group. Histidine loading (500, 800 and 1600 mg/kg) reversed the prolongation of the TL induced by scopolamine. This ameliorating effect of histidine was abolished by alpha-fluoromethylhistidine, an inhibitor of histidine decarboxylase, suggesting that histidine itself has no such ameliorating effect. Moreover, the ameliorating effect of histidine was antagonized by a histamine H1 receptor antagonist, pyrilamine. However, zolantidine, a histamine H2 receptor antagonist, showed no antagonism of the effect of histidine. Thus, histamine, a decarboxylated product of histidine, elicited an ameliorating effect on scopolamine-induced learning deficit via histamine H1 receptors in mice. These findings clearly indicated that there is a close relationship between histaminergic and cholinergic systems in the brain, and that histamine may play certain important roles in learning and memory.
The specificity of practice hypothesis predicts the development of a sensorimotor representation specific to the afferent feedback available during skill acquisition (Proteau, 1992; Proteau, Marteniuk, Girouard, & Dugas, 1987). In the present investigation, we used the specificity of practice hypothesis to test whether skill acquisition through visual imagery would lead to the development of a sensory-specific movement representation similar to one resulting from actual practice. To accomplish this objective, participants practiced walking a 12-m linear path in one of three practice conditions, full-vision (FV), no-vision (NV), or visual imagery (VI), for either 10 or 100 trials. Knowledge of spatial and/or temporal results (KR) was provided to participants following each trial during this phase. Following acquisition, participants completed 10 NV trials without KR. An analysis of root-mean-squared-error (RMSE) indicated NV participants were more accurate than both FV and VI participants in the transfer condition. We believe the equivalence in transfer RMSE between FV and VI suggests that there are similarities between the movement representations attained by FV and VI practice.
Performance of visuo-motor tasks requires the transfer of visual data to motor performance and depends highly on visual perception and cognitive processing, mainly during the learning phase. The primary aim of this study was to determine if the human middle temporal (MT)+/V5, an extrastriate visual area that is known to mediate motion processing, and the primary motor cortex are involved in learning of visuo-motor coordination tasks. To pursue this, we increased or decreased MT+/V5, primary contralateral motor (M1) and primary visual cortex excitability by 10 min of anodal or cathodal transcranial direct current stimulation in healthy human subjects during the learning phase of a visually guided tracking task. The percentage of correct tracking movements increased significantly in the early learning phase during anodal stimulation, but only when the left V5 or M1 was stimulated. Cathodal stimulation had no significant effect. Also, stimulation of the primary visual cortex was not effective for this kind of task. Our data suggest that the areas V5 and M1 are involved in the early phase of learning of visuo-motor coordination.
The present research examined the processes of schema formation in problem solving. In 4 experiments, participants experienced a series of tasks analogous to A. S. Luchins' (1942) water jar problems before attempting to solve isomorphic target problems. Juxtaposing illustrative source instances varying in procedural features along multiple dimensions promoted the construction of a general schema that facilitated solving an isomorphic problem requiring a novel procedure. Exposure to less variant problems led to faster initial learning, but narrower and fixed schemas (mental set), whereas exposure to variant procedures led to slower initial learning, but broader and more flexible schemas. The findings support the dimensional specificity hypothesis: Generalization along 1 dimension facilitates transfer to a target problem differing from the source problems in that dimension.
OBJECTIVE: To provide a standardized and scaleable mechanism for exchanging digital radiologic educational content between software systems that use disparate authoring, storage, and presentation technologies. MATERIALS/METHODS: Our institution uses two distinct software systems for creating educational content for radiology. Each system is used to create in-house educational content as well as commercial educational products. One system is an authoring and viewing application that facilitates the input and storage of hierarchical knowledge and associated imagery, and is capable of supporting a variety of entity relationships. This system is primarily used for the production and subsequent viewing of educational CD-ROMS. Another software system is primarily used for radiologic education on the world wide web. This system facilitates input and storage of interactive knowledge and associated imagery, delivering this content over the internet in a Socratic manner simulating in-person interaction with an expert. A subset of knowledge entities common to both systems was derived. An additional subset of knowledge entities that could be bidirectionally mapped via algorithmic transforms was also derived. An extensible markup language (XML) object model and associated lexicon were then created to represent these knowledge entities and their interactive behaviors. Forward-looking attention was exercised in the creation of the object model in order to facilitate straightforward future integration of other sources of educational content. XML generators and interpreters were written for both systems. RESULTS: Deriving the XML object model and lexicon was the most critical and time-consuming aspect of the project. The coding of the XML generators and interpreters required only a few hours for each environment. Subsequently, the transfer of hundreds of educational cases and thematic presentations between the systems can now be accomplished in a matter of minutes. The use of algorithmic transforms results in nearly 100% transfer of context as well as content, thus providing "presentation-ready" outcomes. CONCLUSION: The automation of knowledge exchange between dissimilar digital teaching environments magnifies the efforts of educators and enriches the learning experience for participants. XML is a powerful and useful mechanism for transfering educational content, as well as the context and interactive behaviors of such content, between disparate systems.
Pregnant rats on the eighth day of gestation (GD 8) received 2 intraperitoneal injections (0.015 ml/g body weight) spaced by an interval of 4 hours, of either 0, 6, 12 18, or 24% (v/v) alcohol solution. Brains of pups sacrificed 24 hours after delivery revealed a dose-related impairment in hemispheric and cerebellar length, width and weight. Statistically significant differences were also observed in body weights of culled pups during Post-partum Day 1. An open field test performed when offspring were 40-45 days old demonstrated a dose-dependent increase in ambulation and rearing scores for both males and females and in defecation scores for females only. Although behavioral studies revealed no effects on acquisition or retention of an active avoidance response, there was a dose-dependent impairment in transfer to passive avoidance conditioning. The present results demonstrate that in the rat, an alcohol insult during GD 8 is sufficient to induce morphological and behavioral alterations in the offspring.
Reinforcement of effortful performance in a given academic task has been found to increase the subsequent performance of other academic tasks. The learned-effort hypothesis assumes that individuals learn which dimensions of task performance are correlated with reinforcement of high effort, and generalize across tasks. Therefore, reinforcement of increased effort in a given dimension of one task should result in greater generalized effort in the same dimension of transfer performance than in another dimension. In accord with this view, preadolescent learning-disabled students who received points for high reading accuracy subsequently produced more accurate drawings and stories than did students whose points had been based upon high reading speed or upon mere completion of the reading task. Students who received points for high reading speed subsequently constructed stories more quickly than did children whose points had been based upon high reading accuracy or upon reading-task completion. Consistent with the more explicit and frequent feedback for accuracy than for speed in most academic tasks, generalized accuracy was much more durable than generalized speed.
This research's purpose was to contrast the representations resulting from learning of the same categories by either classifying instances or inferring instance features. Prior inference learning research, particularly T. Yamauchi and A. B. Markman (1998), has suggested that feature inference learning fosters prototype representation, whereas classification learning encourages exemplar representation. Experiment 1 supported this hypothesis. Averaged and individual participant data from transfer after inference training were better fit by a prototype than by an exemplar model. However, Experiment 2, with contrasting inference learning conditions, indicated that the prototype model was mimicking a set of label-based bidirectional rules, as determined by the inference learning task demands in Experiment 1. Only the set of rules model accounted for all the inference learning conditions in these experiments.
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The contextual interference effect (random practice yields better transfer and retention compared to blocked practice) detected in a study of 24 boys and 33 girls randomly selected (M age = 10.5 yr., SD = .6) performing a linear positioning motor task seemed to dissipate in extended transfer trials.
Greater feedback specificity is generally considered to be beneficial for performance and learning, but the evidence for this generalization is limited. The authors argue that increasing the specificity of feedback is beneficial for initial performance but discourages exploration and undermines the learning needed for later, more independent performance. The results of their transfer experiment demonstrate that increasing the specificity of feedback positively affected practice performance, but its benefits did not endure over time or modification of the task. In addition, feedback specificity negatively affected levels of exploration during practice and interacted with exploration strategies to affect learning. The results suggest that those who received feedback of varying specificity may have learned through different but equally beneficial mechanisms.
Selected theoretical and empirical educational literature relating to peer review were evaluated. The aim of the survey was to provide guidance with regard to the possible introduction of peer review within the author's place of work. The results of the survey highlighted the positive benefits peer review had in terms of professional development, the development of transferable graduate skills, and in more general terms with regard to learning strategies. The conclusions drawn from the survey highlight the importance of broadening the research to part-time students where difficulties with regard to the formation of groups might be encountered, as well as the positive benefit of peer review as a method of assessment.
Myoblast transfer therapy (MTT) was proposed in the 70's as a potential treatment for muscular dystrophies, based upon the early results obtained in mdx mice: dystrophin expression was restored in this model by intramuscular injections of normal myoblasts. These results were quickly followed by clinical trials for patients suffering from Duchenne Muscular Dystrophy (DMD) in the early 90's, based mainly upon intramuscular injections of allogenic myoblasts. The clinical benefits obtained from these trials were minimal, if any, and research programs concentrated then on the various pitfalls that hampered these clinical trials, leading to numerous failures. Several causes for these failures were identified in mouse models, including a massive cell death of myoblasts following their injection, adverse events involving the immune system and requiring immunosuppression and the adverse events linked to it, as well as a poor dispersion of the injected cells following their injection. It should be noted that these studies were conducted in mouse models, not taking into account the fundamental differences between mice and men. One of these differences concerns the regulation of proliferation, which is strictly limited by proliferative senescence in humans. Although this list is certainly not exhaustive, new therapeutic venues were then explored, such as the use of stem cells with myogenic potential, which have been described in various populations, including bone marrow, circulating blood or muscle itself. These stem cells presented the main advantage to be available and not exhausted by the numerous cycles of degeneration/regeneration which characterize muscle dystrophies. However, the different stem candidates have shown their limits in terms of efficiency to participate to the regeneration of the host. Another issue was raised by clinical trials involving the injection of autologous myoblasts in infacted hearts, which showed that limited targets could be aimed with autologous myoblasts, as long as enough spared muscle was available. This resulted in a clinical trial for the pharyngeal muscles of patients suffering from Oculo-Pharyngeal Muscular Dystrophy (OPMD). The results of this trial will not be available before 2 years, and a similar procedure is being studied for Fascio-Scapulo-Humeral muscular Dystrophy (FSHD). Concerning muscular dystrophies which leave very few muscles spared, such as DMD, other solutions must be found, which could include exon-skipping for the eligible patients, or even cell therapy using stem cells if some cell candidates with enough efficiency can be found. Recent results concerning mesoangioblasts or circulating AC133+ cells raise some reasonable hope, but still need further confirmations, since we have learned from the past to be cautious concerning a transfer of results from mice to humans.