SEARCH · PubMed Health

Results for “Learning Curve”

Explore indexed PubMed citations for clinical trials, systematic reviews and public health research. Read source abstracts and follow each citation to its original PubMed record.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 883 records · Page 49Linked to original sources

PubMed2002

A spatial memory task appropriate for electrophysiological recordings.

We developed a novel method for assessing spatial learning that is compatible with the requirements of electrophysiological recording of multiple single neurons. The behavioral task utilized a rectangular track with 8 reward boxes of which a subset contained available food (bait). Errors were scored whenever the rat investigated a non-baited box location (commission), failed to investigate a baited box location (omission), or hesitated in front of a non-baited box location (hesitation). Several controls encouraged the animal to solve the task through allocentric cues rather than through procedural strategies or simple local cue pairing. The learning curve for this task (3-5 d to criterion) was comparable to that of other spatial learning tasks when adequately motivated. The types of errors varied as the animal learned the task. Unlike other spatial learning tasks, the multi-box track allows many repeated samples of the same spatial coordinates within a short period of time to allow, for example, reliable determination of place fields while recording from hippocampal cells. Multiple trials per session also allow for high intensity training important for many learning assessments such as the timing and type of sleep involved in learning and memory.

Analysis of Variance↗

PubMed1982

Learning, memory, and transfer in profoundly, severely, and moderately mentally retarded persons.

Discrimination learning, memory, and transfer capacity were assessed in representative samples of institutionalized retarded persons in order to provide information on trainability. The 56 subjects were selected from moderately, severely, and two levels of profoundly retarded adults. They learned and relearned three successive two-choice discrimination problems. Generally, the higher functioning subjects, defined by IQ and adaptive behavior learned more rapidly than did the lower functioning subjects. Forgetting was related to IQ/adaptive behavior level. Interproblem transfer was negligible at all levels of retardation, but ceiling effects may have obscured positive transfer in the higher functioning groups. Backward learning curves revealed large differences between lower and higher functioning persons in the presolution trials, but once learning began even profoundly retarded subjects solved these problems as rapidly as did the moderately retarded subjects. Ten of the 56 subjects failed to learn all three problems.

Adult↗

PubMed2004

On-line learning through simple perceptron learning with a margin.

We analyze a learning method that uses a margin kappa a la Gardner for simple perceptron learning. This method corresponds to the perceptron learning when kappa = 0 and to the Hebbian learning when kappa = infinity. Nevertheless, we found that the generalization ability of the method was superior to that of the perceptron and the Hebbian methods at an early stage of learning. We analyzed the asymptotic property of the learning curve of this method through computer simulation and found that it was the same as for perceptron learning. We also investigated an adaptive margin control method.

Learning↗

PubMed1995

When encoding fails: instructions, feedback, and registration without learning.

Four experiments replicated and extended the registration-without-learning effect, in which there is little improvement in the ability to discriminate an old target (X) from a highly similar test item (Y) after the first few presentations of X, even though judgments of frequency continue to rise in an open-ended fashion. Forced-choice testing revealed the anomalous form of the learning curve for X-Y discrimination (faster and then slower than the exponential). Effects of several different learning instructions were compared, but these appeared to affect only the level of initial learning, and to do little to promote X-Y discrimination learning on later presentations. The opportunity for self-testing with feedback during study provided no benefits when responding was covert, but did when overt anticipation was required. The findings are discussed in relation to the roles of bottom-up and top-down processing in memory encoding, and to the importance of error-correcting feedback in further structural learning of materials, once the materials have become familiar.

Adult↗

PubMed2001

Of mice and men: virtual Hebb-Williams mazes permit comparison of spatial learning across species.

We developed a computer-generated virtual environment to test humans, for the first time, on the Hebb-Williams mazes. The goal was to provide a standardized test that could be used to directly compare human performance with that of C57BL/6J mice performing in real versions of the mazes. Such a comparison seems crucial if conclusions regarding genetic manipulations of rodents are to be mapped onto human cognitive disorders. The learning curves across species were strikingly similar, lending support to the rodent model of human spatial memory. Humans learned faster than rodents in both the acquisition and the test portions of the protocol, and females of both species were less efficient in solving these problems than males. These results represent the first modern comparison of human and rodent learning that uses the same test of spatial problem solving.

Adult↗

PubMed2007

The emergence of leadership in coordination-intensive groups.

Although group coordination was introduced to psychology in the early 1990s, it was not until the advent of nonlinear dynamical systems (NDS) that it was possible to gain an understanding of how the process of implicit learning and self-organization take place in conditions where no hierarchical (management) influences are involved. This experimental study examined how leaders might emerge from coordination-intensive task groups where verbal interaction is not possible. NDS and game-theoretical research indicate that the presence of leaders is not required to produce coordination. Thus the question remains as to whether leaders would emerge from coordination-intensive task groups in the similar manner to how they emerge from other types of groups. In the experiment, 13 4-person groups were allowed to discuss the coordination (card game) task while performing it; 13 other groups worked nonverbally. Split-plot ANOVA showed that verbalizing groups performed better than nonverbalizing groups overall and showed more acute coordination learning curves. Nonlinear regression for temporal dynamics within verbalizing and nonverbalizing groups showed asymptotic stability for initial coordination learning and transfer to a coordination rule of equal difficulty, but a chaotic function was observed when the teams switched to a more difficult coordination rule. A questionnaire measured leadership emergence at the end of the game along with other social contributions to the groups' efforts. The average level of leadership emergence for individuals did not differ between verbal and nonverbal conditions, although differences in other social contributions were observed. This experiment illustrates, furthermore, how the nonlinear science paradigm produces new hypotheses concerning verbalization that would not have been formulated otherwise. New avenues of study concerning coordination, leadership, and hierarchies are also discussed.

Adult↗

PubMedDate not supplied

A growth curve model of learning acquisition among cognitively normal older adults.

The objective of this study was to model recall and learning on the Auditory Verbal Learning Test using latent growth curve techniques. Participants were older adults recruited for the ACTIVE cognitive intervention pilot. A series of nested models revealed that an approximately logarithmic growth curve model provided optimal fit to the data. Although recall and learning factors were statistically uncorrelated, a fitted multivariate model suggested that initial recall was significantly associated with demographic characteristics but unrelated to health factors and cognitive abilities. Individual differences in learning were related to race/ethnicity, speed of processing, verbal knowledge, and global cognitive function level. These results suggest that failing to recognize initial recall and learning as distinct constructs clouds the interpretation of supraspan memory tasks.

Aged↗

PubMed2003

[Manual skills in anaesthesiology].

Assessment in anaesthesia traditionally takes the form of written papers and oral examinations. These are important for assessing trainee's knowledge and judgement, but do not test for competency in practical skills, which is essential for successful clinical practice. The presence of learning curves for practical skills in anaesthesia is now well recognized and they are useful tools to monitor a learning process. From these, estimates of the number of procedures that must be performed by trainees in order to reach an acceptable success rate can be produced. It is clear that these figures give some help for the rational design of training programs, however, numbers alone do not provide a sufficient basis to declare a trainee competent for a given procedure. Not only technical skills need to be taught, but also decision-making and even more important behavioral skills. In clinical practice there are often problems in providing all the necessary training on patients and by this reorganization of residency programs may be necessary. However, the role of medical simulation in the assessment of anesthetists in training is still unclear, and the introduction of simulator-based tests may be premature.

Anesthesia, Conduction↗

PubMed2002

Laparoscopic and robot assisted radical prostatectomy: establishment of a structured program and preliminary analysis of outcomes.

PURPOSE: The technique of laparoscopic radical prostatectomy is difficult to master and is associated with a steep learning curve. We hypothesized that a structured approach to establishing a laparoscopic prostatectomy program would diminish complications during the learning process and that robotic technology would be useful in learning the operation. MATERIALS AND METHODS: A structured laparoscopic radical prostatectomy program was introduced at the Vattikuti Urology Institute on October 23, 2000. One of 2 surgeons with a combined experience of more than 500 laparoscopic radical prostatectomies performed or supervised the first prostatectomies, training a third surgeon with extensive "open" surgical skills but no laparoscopic experience. The "trained" surgeon then started performing the operation independently with robotic assistance. The results of this approach were analyzed at the end of 12 months. RESULTS: We performed 48 laparoscopic radical prostatectomies and 50 robot assisted prostatectomies within the 12-month period. The preoperative and intraoperative demographical variables were comparable in both groups as were the operative times, changes in hemoglobin concentrations, durations of hospitalization, positive margin rates and overall complication rates. All measured parameters were comparable to the "best-in-class" values for laparoscopic radical prostatectomy reported in the literature. CONCLUSIONS: A structured approach minimizes complications during the establishment of laparoscopic radical prostatectomy program. Robotic assistance helps skilled "open" surgeons learn the technique of laparoscopic radical prostatectomy.

Humans↗

PubMed2005

Team working to improve outcome in vestibular schwannoma surgery.

The concept of the 'learning curve' in the early years of consultant appointment is no longer acceptable and yet, for most complex operations, learning is a career-long process. Sub-specialization offers part of the solution to this problem by concentrating expertise, but there remains the question of how to introduce new team members without adversely affecting patient outcome. Shortened training and an increasingly aware public, who are more questioning of the experience and outcomes of those treating them, has required the surgical profession to move away from individual consultant practice and embrace team-working. When, in 1997, a second neurosurgeon joined the skull base team at Addenbrooke's Hospital, his introduction to acoustic neuroma surgery was mentored and operative cases were carefully selected at first. In this article, we discuss our experience with consultant mentoring, and compare the results of the first 100 translabyrinthine acoustic neuroma operations performed under this system with the first cohort of a similar number of patients published from Cambridge in 1989.

Adolescent↗

PubMed1990

Performance on traditional matching to sample, non-matching to sample, and object discrimination tasks by 12- to 32-month-old children. A developmental progression.

Children 12 to 36 months old were tested on DMS, DNMS, and object discrimination tasks in a WGTA with procedures that closely followed those used previously with monkeys. Mastery of DNMS showed a clear developmental progression. The youngest children (12-15 months old) required extensive training, and they failed to reach criterion until they were 15-18 months old. The differentially slower learning of the youngest children cannot be attributed to "performance" deficits (perceptual, motivational, or associational inabilities) or the inability to make 2-part responses, because a test of object discrimination showed that even 12-month-old children can perform with accuracy in the WGTA testing situation. Analysis of learning curves along with additional tests of memory provided evidence that the youngest children are (1) less proficient in learning the novelty-reward rule and (2) less proficient in memory for a particular stimulus item. Furthermore, we found that a task that we think requires learning two rules, a DMS task, was even more difficult for children to master. These results together with data collected on brain-damaged humans and monkeys indicate that the DNMS and DMS tasks, when applied to children, may provide insight into the functional maturation of brain areas responsible for memory, rule-learning, and behavioral inhibition.

Aging↗

PubMedDate not supplied

The relationship between serum testosterone level and visuomotor learning in right-handed young men.

The relationship between serum testosterone level and visuomotor of learning of hand skill was studied in right-handed young men. Hand skill was assessed by a peg moving task. Peg moving times for the right and left hands linearly decreased at each successive trial (visuomotor learning). The peg moving times for the right and left hands were found to be negatively linearly related to serum testosterone levels: there was a direct relationship between hand skill and testosterone, which was more prominent for the right than the left hand. The slopes of the learning curves for the right hand were found to be equal in subjects with low, normal, and high testosterone. The intercepts of these curves exhibited a shift toward a better hand skill from low- to high-testosterone subjects. The visuomotor learning for the left hand was found to be better in subjects with normal and high testosterone than those with low testosterone. It was concluded that testosterone would favor the visuomotor development especially of the left cerebral hemisphere, probably at puberty; the motor learning of this hemisphere does not seem to be associated with testosterone. Testosterone seems to be advantageous for the visuomotor performance as well as for the motor learning of the right cerebral hemisphere.

Adolescent↗

PubMed2006

Angioplasty and stenting to treat occlusive vascular disease.

The advent of effective percutaneous treatment of occlusive vascular lesions by angioplasty and stenting is one of the most important contributions to medical care early in the 21st century. Evaluation of angioplasty and stenting procedures is still in a very early phase. New types of stents and other technologies and devices are being continuously developed and there is a definite learning curve. The experience, training, and number of procedures clearly relate to outcomes, and many different specialists are still learning and so far have not had optimal experience. This review provides an overview of studies that have examined the efficacy of stenting in conjunction with balloon angioplasty for carotid atherosclerosis compared with endarterectomy. Also discussed are angioplasty/stenting of other neck arteries and intracranial arteries and the key issues surrounding percutaneous intervention, including patient selection criteria, clinical assessment of lesions most suitable for treatment, the use of distal protective devices and drug-eluting stents, and recommendations for physician selection.

Angioplasty, Balloon↗

PubMed2004

Technique and considerations when using external fixation as a standard treatment of femoral fractures in children.

Femoral fractures in children can be treated effectively and with a low complication rate by using external fixation. However, as with most treatment modalities there is a learning curve to be considered. The aim of this paper is to report "tricks" and different considerations that we have learned to be of value based on experience gained during a prospective and consecutive study of 98 femoral fractures in children aged 3-15 years. Our experience is based on the use of a unilateral fixator with the option to apply axial dynamisation. Traction prior to operation is not needed if the child is operated on within 24h. During surgery a traction table will prevent significant malrotation and facilitate reduction prior to insertion of the pins. Four 4 or 5mm pins are sufficient for adequate stability in children. Transverse skin incisions are preferable for pin insertion as the scars become smaller and the soft tissue irritation during activity is less when compared with longitudinal incisions. Unrestricted weight-bearing can be allowed. A nihilistic approach to pin site care with daily showers is as effective as more aggressive treatment with local antiseptics. Pin infections can occur but are mild and can be treated locally or with a short period of antibiotics taken orally. Pin-loosening and deep infections are very uncommon. By using external fixation, malunion, overgrowth or delayed union can almost be avoided completely. Re-fractures are rare and occur only after significant trauma. Treatment time is relatively short. No physiotherapy or further protection of the leg is necessary during or after healing.

Adolescent↗

PubMed2004

The role of dopamine in learning, memory, and performance of a water escape task.

Dopamine-deficient (DD) mice have selective inactivation of the tyrosine hydroxylase gene in dopaminergic neurons, and they die of starvation and dehydration at 3-4 weeks of age. Daily injections of L-DOPA (50 mg/kg, i.p.) starting approximately 2 weeks after birth allow these animals to eat and drink enough for survival and growth. They are hyperactive for 6-9 h after receiving L-DOPA and become hypoactive thereafter. Because these animals can be tested in the presence or absence of DA, they were used to determine whether DA is necessary for learning to occur. DD mice were tested for learning to swim to an escape platform in a straight alley in the presence (30 min after an L-DOPA injection) or absence (22-24 h after an L-DOPA injection) of dopamine. The groups were split 24 h later and retested 30 min or 22-24 h after their last L-DOPA injection. In the initial test, DD mice without dopamine showed no evidence of learning, whereas those with dopamine had a learning curve similar in slope to controls but significantly slower. A retest after 24 h showed that DD mice can learn and remember in the absence of dopamine, leading to the inference that the lack of dopamine results in a performance/motivational decrement that masks their learning competence for this relatively simple task.

Analysis of Variance↗

PubMed2005

A new mathematical model for assessment of memorization dynamics.

A new memory model is proposed based on regression analysis and exponential- shaped learning curves. The efficacy of the model is tested with several types of experiments including food aversion in snails, maze learning in rats and memory tests for adults and children. The model is also tested on drug abusers and alcoholics. The results of goodness of fit tests indicate that our model can accurately be used to predict the memory dynamics of diverse experiments and populations. The model can also be used to predict both group and individual performance. The application of the model to detect memory impairment is discussed, as are limitations.

Adult↗

PubMed2006

Cued recall from image and sentence memory: a shift from episodic to identical elements representation.

The applicability of the identical elements (IE) model of arithmetic fact retrieval (T. C. Rickard, A. F. Healy, & L. E. Bourne, 1994) to cued recall from episodic (image and sentence) memory was explored in 3 transfer experiments. In agreement with results from arithmetic, speedup following even minimal practice recalling a missing word from an episodically bound word triplet did not transfer positively to other cued recall items involving the same triplet. The shape of the learning curve further supported a shift from episode-based to IE-based recall, extending some models of skill learning to cued recall practice. In contrast with previous findings, these results indicate that a form of representation that is independent of the original episodic memory underlies cued-recall performance following minimal practice.

Cues↗

PubMed2004

Regional brain activation during concurrent implicit and explicit sequence learning.

We used event-related fMRI to identify the brain regions engaged during explicit and implicit sequence learning (ESL and ISL, respectively). Twenty-four subjects performed a concurrent ESL and ISL task. Behavior showed learning in both conditions. Prefrontal (PFC), striatal, anterior cingulate cortex (ACC) and visual regions (V1, V2 and V3) were engaged during both ESL and ISL. With ESL there was increased activity in the visual regions on the predictable (i.e. learned pattern) trials. With ISL, however, there was a relative decrease in activity in visual regions. The opposite patterns in the visual regions highlight the different effects of ESL and ISL. The learning process was distinguished from the result of learning, by fitting subjects' functional magnetic resonance imaging data to their learning curve. This analysis revealed more extensive PFC activity during ESL and caudal ACC activity specific for the result of learning analysis, when the expected response was violated. Our results suggest a relative dissociation of the brain regions engaged during ESL and ISL, whereby ESL and ISL can be viewed as partially distinct but overlapping parallel processes.

Adolescent↗