Second Phase Of Training Research Articles

Rescue and dissemination of ancestral knowledge of the Montuvio people to produce traditional soap

The work deals with the recovery of ancestral knowledge in the Montuvio Manabita people as an extension proposal to the community, for which the main objective was to disseminate ancestral knowledge through the planting of the traditional soap tree to produce natural liquid soap that can be used to wash clothes by hand, in a washing machine and even as a shampoo. The project was located in the El Limón commune of the Picoazá rural parish of the Portoviejo canton, in the Manabí province of the zone4. We worked with an intentional sample of 20 families, the technique of focus groups; The method to be used contemplates two phases, the first of planting the soap on the edges of the farms, preferably on the banks of the irrigation canals or the river, and the second phase of training on the production of soap using soap seeds. The result was that the dissemination of ancestral knowledge in the communities constitutes a practical application that can contribute as a way of reactivating the local post-covid-19 economy, applying ancestral techniques for the elaboration of various products from the Manabí field.

Optimized linear regression control of DC motor under various disturbances

Abstract In this study, an optimized linear regression controller is proposed for velocity control of DC motor. System is tested under disturbances of different types. Step, sinusoidal and trapezoidal functions are used as reference input. A linear single layer network of weights is used to calculate the necessary armature voltage by giving past measured velocity, past reference and certain amount of future reference as inputs. Training data are generated using Proportional Integral (PI) controller parameters which are optimized using particle swarm optimization (PSO). In this first phase of training, pseudo-inverse solution is used to find the coarse parameters of the network. These parameters give suboptimal results with low performance even lower than that of PSO-optimized PI controller. In the second phase of training, parameters of the network are fine-tuned using PSO algorithm again, this time for optimization of network parameters. Quite encouraging results including up to more than 1,500% increase in performance are obtained and reported.

EPortfolio in Teacher Education and Academic Further Education

Private and professional life is more and more shaped by rapid changes in society and technology. That’s why continuous further education is essential in order to meet the new requirements. In the context of lifelong learning, this article focuses primarily on “learning to learn” as a key competence (European Union, 2018). Therefore, it is essential to develop the ability to self-regulated learning (Zimmerman, 2000) in the first phase of academic training and beyond. Learners must be able to plan, carry out and evaluate their learning process. In order to monitor it successfully, it also requires the ability to reflect.
 One instrument that can help learners to regulate their learning process is the ePortfolio (McAllister et al., 2008). In an ePortfolio learners can set their goals individually, document and reflect on their progress with the help of artefacts and thus assess their learning strategies and adapt them, if necessary. Futhermore, outcomes of informal learning can be presented within an ePortfolio as well as outcomes of formal learning activities. For example, in the field of teacher education ePortfolios are used quite widely. The ability to reflect one’s actions is an important aspect of professionalism, which helps teachers to improve their teaching (Schön, 1983). Therefore, it is important, as a prospective teacher, to be able to realistically assess one's own abilities and to know how to acquire new competencies. Teachers have to question their actions constantly and adapt them if necessary. In the German State of Baden-Württemberg keeping an ePortfolio is obligatory for students during the practical phases and is continued in the second phase of training, during the internship. A second field, where ePortfolio is gaining importance, is the academic continuing education. The Academy of Advanced Studies at the University of Konstanz offers academic programmes for professionals. A pilot project will be launched next semester in the part-time bachelor study programme in “Motor Neurorehabilitation” for qualified professional therapists in healthcare. Primarily, the implementation of an ePortfolio in this context aims at giving learners the opportunity to manage and personalise their own digital archive (collection of documents). Secondly, it enables the students to reflect more consciously the inputs and outputs collected - particularly during the time they will be attending their practical internships. Thus, the participants should develop a stronger reflective and critical thinking with regard to the acquired new methods and the experiences collected. Furthermore, the ePortofolio should facilitate group work and encourage interaction with other colleagues (peer review) and/or instructors.
 This paper discusses the possibilities of using ePortfolios in teacher training and in academic further education. Based on a theoretical concept for learning and professionalizing with ePortolios in higher education and life long learning, as mentioned before, the potentials in the different fields of application will be presented. Furthermore, we will point out the difficulties and challenges associated with the introduction of an ePortfolio. Finally, an outlook on what is planned for the further development of ePortfolio at the University of Konstanz will be given.

A Collaborative Training Program to Assess Mercury Pollution from Gold Shops in Guyana’s Artisanal and Small-Scale Gold Mining Sector

A three-phase, 11-day training program designed to monitor elemental mercury (Hg0) emissions originating from gold shops was conducted in Georgetown and Bartica, Guyana, during May of 2019. The first phase consisted of interactive lectures and discussions on mercury use in artisanal and small-scale gold mining throughout Guyana, the region, and the world. In addition, specific training in the theory and use of analytical instrumentation to quantify Hg0 pollution associated with the processing of amalgams and sponge gold occurred. Trainees participated in the mapping of smelting facilities in Georgetown where, outside of one gold shop, Hg0 concentrations exceeded 100,000 ng/m3. During the second phase of training, a subset of trainees traveled to Bartica, where they mapped the town center to identify point sources of Hg0 pollution, all of which corresponded to the location of shops where amalgams and sponge gold were heated and purchased. Once mapped, Hg0 concentrations were measured during the smelting of gold inside the Guyana Gold Board (GGB) facility and two privately-owned gold shops. Maximum Hg0 concentrations at the GGB facility did not exceed 98,700 ng/m3 during the measurement period, while maximum concentrations at the two privately owned shops were measured as 527,500 ng/m3 and 302,200 ng/m3. With guidance from the training team, trainees were responsible for the collection and interpretation of all data. The third phase of the training involved the collaborative production of a report summarizing the findings from the training. This work represents the first formal training opportunity for the assessment of Hg0 concentrations in and around gold shops in Guyana, and provides baseline data to assist the government of Guyana to generate air quality standards for Hg0 emissions.

Explaining learned predictiveness: Roles of attention and integration of associative structures.

In 3 experiments, participants were trained in an associative learning paradigm in which they learned the relation between consumption of certain foodstuffs and the type of allergic reaction shown by a fictional patient. Experiment 1 demonstrated the learned predictiveness effect, showing that cues that had served as good predictors of outcomes in an initial phase of training were especially effective in a test given after a second phase of training in which learning about the same cues, but with different outcomes, had been required. Experiment 2 showed that this effect could be obtained when the two phases of training occurred in reverse order, so that the critical cues were established as good or bad predictors only after the associations tested in the final test had been acquired. This learned predictiveness effect cannot be explained by an enhancement of the associability of the predictive cues that facilitated learning about them in phase two. This encouraged us to consider 2 alternatives to associability for explaining learned predictiveness: (a) that training a cue as a good predictor increases its effective salience, thus enhancing its power to evoke responding on test and (b) that learned predictiveness is the result of a nonattentional process in which subjects integrate information acquired in the separate phases of training. Support for the latter came from Experiment 3, which showed that a modified test procedure, designed to reduce the tendency to integrate across phases, eliminated the learned predictiveness effect. (PsycINFO Database Record (c) 2019 APA, all rights reserved).

Long-term outcome evaluation of faculty development program for dental educators: A questionnaire survey

Purpose: Faculty development programs (FDP) are essential to equip teachers with the knowledge and skills required to fulfil their multiple roles. In India, dental educators undergo minimal training in teaching and related responsibilities. Long-term outcomes of such programs are not reported in any literature. This questionnaire survey was conducted to analyze the long-term outcome of a FDP, conducted for dental educators, at four levels of Kirkpatrick's model of evaluation. Methods: Beginning in 2013, dental educators in a health-professions university underwent FDP in two phases. The topics covered were toward the instructional development of the faculty, such as education as system, teaching-learning principles/methods/media, assessment and evaluation principles/methods, and curriculum process. Medical educators of the university conducted the first phase of the training over an 8-month period. Subsequently, the Dental Education Unit was formed, which then conducted the second phase of training for the newly recruited faculty over 4 months. The immediate outcome was assessed with feedback and a posttest. Long-term outcome, at the end of the 3rd year, was evaluated using an online questionnaire that was sent to 56 dental educators who were trained in both phases. Results: A response rate of 100% was obtained. About 94% of the faculty reported satisfaction toward the workshop and a positive attitudinal change; 85% of them reported knowledge/skill gain and changes in their teaching practices; 78% of the faculty perceived changes in educational policies of the institution; and 70% of them perceived an improvement in students' performance. Conclusion: This 3-year follow-up evaluation showed acceptable changes in the dental educators' teaching competence, the institution's educational policies, and in the students' performance, as perceived by the study participants, after the FDP.

Equilibrium Propagation: Bridging the Gap between Energy-Based Models and Backpropagation.

We introduce Equilibrium Propagation, a learning framework for energy-based models. It involves only one kind of neural computation, performed in both the first phase (when the prediction is made) and the second phase of training (after the target or prediction error is revealed). Although this algorithm computes the gradient of an objective function just like Backpropagation, it does not need a special computation or circuit for the second phase, where errors are implicitly propagated. Equilibrium Propagation shares similarities with Contrastive Hebbian Learning and Contrastive Divergence while solving the theoretical issues of both algorithms: our algorithm computes the gradient of a well-defined objective function. Because the objective function is defined in terms of local perturbations, the second phase of Equilibrium Propagation corresponds to only nudging the prediction (fixed point or stationary distribution) toward a configuration that reduces prediction error. In the case of a recurrent multi-layer supervised network, the output units are slightly nudged toward their target in the second phase, and the perturbation introduced at the output layer propagates backward in the hidden layers. We show that the signal “back-propagated” during this second phase corresponds to the propagation of error derivatives and encodes the gradient of the objective function, when the synaptic update corresponds to a standard form of spike-timing dependent plasticity. This work makes it more plausible that a mechanism similar to Backpropagation could be implemented by brains, since leaky integrator neural computation performs both inference and error back-propagation in our model. The only local difference between the two phases is whether synaptic changes are allowed or not. We also show experimentally that multi-layer recurrently connected networks with 1, 2, and 3 hidden layers can be trained by Equilibrium Propagation on the permutation-invariant MNIST task.

Effects of a structured 20-session slow-cortical-potential-based neurofeedback program on attentional performance in children and adolescents with attention-deficit hyperactivity disorder: retrospective analysis of an open-label pilot-approach and 6-month follow-up.

ObjectiveThe aim of this approach was to conduct a structured electroencephalography-based neurofeedback training program for children and adolescents with attention-deficit hyperactivity disorder (ADHD) using slow cortical potentials with an intensive first (almost daily sessions) and second phase of training (two sessions per week) and to assess aspects of attentional performance.Patients and methodsA total of 24 young patients with ADHD participated in the 20-session training program. During phase I of training (2 weeks, 10 sessions), participants were trained on weekdays. During phase II, neurofeedback training occurred twice per week (5 weeks). The patients’ inattention problems were measured at three assessment time points before (pre, T0) and after (post, T1) the training and at a 6-month follow-up (T2); the assessments included neuropsychological tests (Alertness and Divided Attention subtests of the Test for Attentional Performance; Sustained Attention Dots and Shifting Attentional Set subtests of the Amsterdam Neuropsychological Test) and questionnaire data (inattention subscales of the so-called Fremdbeurteilungsbogen für Hyperkinetische Störungen and Child Behavior Checklist/4–18 [CBCL/4–18]). All data were analyzed retrospectively.ResultsThe mean auditive reaction time in a Divided Attention task decreased significantly from T0 to T1 (medium effect), which was persistent over time and also found for a T0–T2 comparison (larger effects). In the Sustained Attention Dots task, the mean reaction time was reduced from T0–T1 and T1–T2 (small effects), whereas in the Shifting Attentional Set task, patients were able to increase the number of trials from T1–T2 and significantly diminished the number of errors (T1–T2 & T0–T2, large effects).ConclusionFirst positive but very small effects and preliminary results regarding different parameters of attentional performance were detected in young individuals with ADHD. The limitations of the obtained preliminary data are the rather small sample size, the lack of a control group/a placebo condition and the open-label approach because of the clinical setting and retrospective analysis. The value of the current approach lies in providing pilot data for future studies involving larger samples.

Training on Ergonomic Risk Prevention for Telemarketing Operator: Methodological Aspects

The Ministry of Labor and Employment - MTE in 2007 approved an attachment on the Regulatory Standard 17 (NR17 - Ergonomics) for telemarketing activity. Thus, companies should adopt ergonomics in the workplace and train your operators on occupational hazards and preventive measures. After eight years of regulation, also points up the breach of the said rule and the lack of information by the workers about the occupational risks they face and the preventive measures. This article aims to present the methodology used in training on prevention of occupational risks, based on Annex II of NR17 to telemarketers. Methodology: The process starts with the visit and participant observation of the work environment. Then schedule to training with all the OT and managers. After occurs a 04hours clarifying trainning about occupational hazards and preventive measures using active methodology with case studies. Practical activities are carried out to learn to adjust the furniture, sanitize the equipment, voice preparation techniques, visual and mental relaxation and lengthening body. After 06 months as recommended by the NR, there is a second phase of training. Results: The research showed the importance of educating the worker about to occupational risks and the adoption of preventive measures. There was the training of 100% of the operators. In the end, 90% of workers considered the training important and will help in their day-to-day work. In the second phase, after 06 months, all remained at work and 100% participated in the training. In the end 85% considered the training important and will help in their day-to-day. 100% state that the adoption of preventive measures also depends on the company's commitment.

4WD mobile robot for autonomous steering using single camera based vision system

Purpose – The purpose of this paper is to demonstrate System-of-Systems (SoS) approach to design and development of unmanned robotic platform for greenhouse agricultural application. Design/methodology/approach – SoS design approach is important in developing engineering products. It was observed that while system integration considers designs in a multi-disciplinary level framework, SoS is viewed as a solution focussed approach. In this paper, the authors have demonstrated SoS approach to develop a mobile robot platform. The wheels of the platform are independently controlled by using brushless DC and stepper motors based on fieldbus type Distributed Control System scheme. Findings – The constraints for autonomous traveling were identified during the first phase followed by development of 12 distinct sub-routines during second phase of training. Optimal camera installation angle, driving speeds, steering angle per pixel were found to be valuable constraints for feed-forward parameters for real-time driving. The platform was field tested in a tomato planted greenhouse for yield and weed mapping. Research limitations/implications – The paper focusses on studying vision-based autonomous four-wheel-drive (4WD) constraints and their implementation limitations. Practical implications – The platform was field tested in a tomato planted greenhouse for yield and weed mapping. Social implications – The platform can be used for agricultural operations such as crop scouting, monitoring, spraying, and mapping in a medium to large-scale greenhouse setting. Originality/value – The research and presentation is original. Starting from its mechanical specification to wheel performance study, development of path patterns for training and global navigation algorithm for testing and validation were achieved. The platform can autonomously be driven without any manual intervention.

Attentional mechanisms in learned predictiveness.

Cues that reliably predict an outcome in an initial phase of training (Phase 1) are learned faster in a second phase of training (Phase 2) than cues that were unreliable in Phase 1. This result is observed despite objectively equal relationships between the cues and the outcomes in Phase 2, and consequently constitutes a nonnormative bias in learning. The present experiments sought to confirm that this learned predictiveness effect is the product of attentional processes (Experiment 1), and to test further whether these processes are under voluntary control or are automatic in nature (Experiment 2). In addition to the usual outcome prediction measure, eye-gaze behavior was also monitored. The results indicated an important role for top-down strategic attentional processes in the learned predictiveness task. In contrast, no evidence for an automatic attentional bias was found.

An Infinite Mixture Model of Context-dependent Learning and Extinction

Event Abstract Back to Event An Infinite Mixture Model of Context-dependent Learning and Extinction Dominant theories of human and animal learning posit that in classical conditioning, one of the most basic forms of learning, animals learn to make associations between different stimuli in the environment. These associations are then used to predict future events based on current observations. Although this framework is powerful, we argue that a wealth of behavioral evidence is more consistent with an account of learning in which animals make more complex inferences about the environment. Most notably, responding to a conditioned stimulus appears to depend not only on the reinforcement history of the stimulus but also on its relationship to contextual stimuli (such as the experimental chamber). We thus model learning as inference over latent causes of observed stimuli, rather than of direct causal relationships between them. We focus on two extensively-studied animal conditioning paradigms, latent inhibition and renewal. In latent inhibition, the acquisition of a conditioned response to a cue that is paired with reinforcement is retarded if the cue was previously presented without reinforcement. A change of context between the initial exposure to the unreinforced cue and the subsequent training reduces this retardation. In renewal, the cue is first presented paired with reinforcement (conditioning) in one context and then presented without reinforcement (extinction) in another context, leading to loss of conditioned responding. Returning the animal to the conditioning context renews conditioned responding. Renewal also occurs when the animal is tested in a completely novel context. In both latent inhibition and renewal, lesioning the hippocampus prior to the second phase of training eliminates context-dependence. A similar pattern is observed in infant rats, whose behavior seems to not be sensitive to context. We suggest that these and other context-dependent learning phenomena can be explained by a normative statistical model in which the animal performs inference of latent causes in an infinite mixture model. In contrast to classical associative theories, the infinite mixture model assumes that each observation (trial) is generated by a single latent cause, selected from an unbounded set of latent causes. This identifies the computational problem being solved by the animal as that of how to assign observations to discrete latent causes (ie, clustering) and use these to predict reinforcement. The infinite capacity of the model enables the animal to infer new clusters as it collects observations. Our simulations show that the model predicts the context-dependence of latent inhibition and renewal. We also show how restricting the model's ability to infer new clusters explains developmental changes in learning as well as the effects of hippocampal damage. The key difference between the infinite mixture model and previous models is the explanation of learning as inference over latent causes rather than the formation of associations between observed stimuli, giving rise to novel predictions regarding the effects of training length on learning and context effects, and suggesting manipulations that could reverse behavioral phenomena that were previously regarded as fixed constraints on learning. The model also has implications for understanding context-dependent relaspe in drug addiction and anxiety disorders. Conference: Computational and systems neuroscience 2009, Salt Lake City, UT, United States, 26 Feb - 3 Mar, 2009. Presentation Type: Oral Presentation Topic: Oral Presentations Citation: (2009). An Infinite Mixture Model of Context-dependent Learning and Extinction. Front. Syst. Neurosci. Conference Abstract: Computational and systems neuroscience 2009. doi: 10.3389/conf.neuro.06.2009.03.323 Copyright: The abstracts in this collection have not been subject to any Frontiers peer review or checks, and are not endorsed by Frontiers. They are made available through the Frontiers publishing platform as a service to conference organizers and presenters. The copyright in the individual abstracts is owned by the author of each abstract or his/her employer unless otherwise stated. Each abstract, as well as the collection of abstracts, are published under a Creative Commons CC-BY 4.0 (attribution) licence (https://creativecommons.org/licenses/by/4.0/) and may thus be reproduced, translated, adapted and be the subject of derivative works provided the authors and Frontiers are attributed. For Frontiers’ terms and conditions please see https://www.frontiersin.org/legal/terms-and-conditions. Received: 04 Feb 2009; Published Online: 04 Feb 2009. 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Successive positive contrast in one-way avoidance behavior with Roman low-avoidance rats

The inbred Roman High - (RHA-I) and Roman Low-Avoidance (RLA-I) rats, psychogenetically selected for rapid (RHA-I) vs. extremely poor (RLA-I) acquisition of two-way active avoidance, exhibit a lower or a higher level of fearfulness, respectively, that can be observed in many laboratory anxiety models. The present study analyzed the performance of female RLA-I and RHA-I rats in a successive positive contrast situation induced during one-way avoidance learning. Three groups of RLA-I and three of RHA-I rats (1–30, 30–30 and 1–1 groups, the numbers stand for the time spent in the safe compartment during the first and second phase of training) were trained to avoid an electric foot-shock administered in a “danger” compartment, by running from this compartment to a “safe” one. Only RLA-I rats showed a significant positive contrast effect, in such a way that the reinforcement increase from the lower (1 s spent in safety) to the higher reward (30 s) led to a response enhancement, surpassing the performance of rats trained with the low (1–1 s) or the high (30–30 s) reward from the beginning of training. The results are discussed in the context of an opponent process theory based upon the interaction between the motivational strength of fear and the incentive value of relief taking place during one-way avoidance learning.

Retrospective revaluation effects in the conditioned suppression procedure

In four experiments using the conditioned suppression procedure, rats received initial reinforced training with two compound stimuli, AX and BY, each compound consisting of one auditory and one visual element. After a second phase of training consisting of nonreinforced presentations of A, the suppression governed by X and Y was tested. In Experiment 1 X evoked slightly less suppression than Y (a mediated extinction effect). This outcome was obtained when the auditory cues served as X and Y(Experiment 1a), when the visual cues served as X and Y(Experiment 1b), and when the number of nonreinforced presentations of A was increased (Experiment 1c) from 18 to 216. In Experiment 2, however, in which the initial training was given with serial compounds (i.e., A --> X and B --> Y) X evoked more suppression than Y (a recovery-from-overshadowing effect). It was argued that extinction of A engages two learning processes, one increasing the effective associative strength of its associate (X) and one reducing it, and that the balance between these two depends on the specific conditions of training.

Evaluation of the Relationship between Student Performance on the PACKRAT And PANCE Examinations

Purpose: The purpose of this study is to determine the relationship between student scores on the Physician Assistant Clinical Knowledge Rating and Assessment Tool (PACKRAT) and performance on the Physician Assistant National Certifying Examination (PANCE). Methods: PACKRAT scores from students enrolled in the Interservice Physician Assistant Program (IPAP) following their didactic year of training were compared to the PANCE scores by the same students. The PACKRAT examination was administered to students within the last few weeks of their first year of training, just prior to beginning their clinical rotations. The PANCE scores represent the first attempt by IPAP graduates to attain certification shortly following completion of their second phase of training (clinical rotations). The study included those students that began their training in May of 1999 through May 2001. The first didactic year is divided into three separate trimesters and a new class of students begins each four months. This represents students included in seven different classes (n = 375). The relationship between the scores was evaluated by determination of the correlation coefficient. Analysis of the predictive value of PACKRAT results with respect to passing the PANCE was accomplished using logistic regression. Results: Correlation between PACKRAT and PANCE scores showed a correlation coefficient of 0.668 (P<0.001). Logistic regression showed a significant relationship between PACKRAT scores and PANCE performance (P<0.001). A PACKRAT score of < 55% (raw score = 124) had a sensitivity of 77.2% and specificity of 83.3%. Conclusions: The scores obtained by the students on the PACKRAT examination correlated well with those obtained on the first administration of the PANCE. In addition, PACKRAT scores proved to have a strong predictive value of student pass/fail performance on the PANCE.

Two-way fuzzy adaptive identification and control of a flexible-joint robot arm

Abstract The objective in this paper is to apply our proposed two-way fuzzy adaptive system that makes use of intuitionistic fuzzy sets to the identification and model-based control of a flexible-joint robot arm. Uncertainty and inconsistency are modelled in the proposed system such as uncertainty is the width of the interval introduced by the independent assignment of membership and nonmembership functions of the intuitionistic fuzzy sets; and inconsistency is the violation of the consistency inequality in this assignment. We reduce uncertainty and inconsistency through a two phase training. The first phase is to reduce inconsistency introduced by the inconsistent assignment of membership and nonmembership functions. The resultant system is an almost consistent two-way fuzzy adaptive system. Thus, an evaluation of the degree of reduction of inconsistency is needed and is carried out at the end of this phase by forming the shadowed set patterns of the membership and nonmembership functions after first phase of training. The system is further trained for a second phase in order to reduce uncertainty. The system performance has shown that this second phase of training renders the system totally one-way fuzzy adaptive.

The role of mediated conditioning in acquired equivalence.

In Experiment 1 rats received initial training in which delivery of a sucrose pellet was signalled by an auditory cue. This cue was then paired with shock in a second phase of training. In a test the rats showed an unwillingness to perform an instrumental response that yielded the sucrose pellet. This was interpreted as indicating that the associatively activated representation of the pellet had acquired aversive properties during the shock-reinforced stage of training. Experiment 2 replicated this mediated conditioning effect making use of a Phase 1 training procedure, modelled on that used by Honey and Hall (1989) to demonstrate acquired equivalence of cues, in which two auditory cues were each used to signal sucrose pellets. A further test revealed that this training resulted in enhanced generalization between these two cues. It was argued that this effect is mediated by the conditioned aversive properties of the common associate of the two auditory cues.

Backward sensory preconditioning.

In Experiments 1 and 2, rats received initial training in which two neutral events were presented as a serial compound (A--~X). Subsequent training with A as a signal for shock was found to endow X with the ability to evoke the conditioned response of suppression. Experiment 2 also showed that responding to X was diminished if, prior to testing, Stimulus A underwent extinction. Two possible mechanisms for these findings are considered: (a) that X elicits responding through the associative chain X-A-shock, and (b) that A activates a representation of X that gains direct associative strength during conditioning with A and loses it during extinction of A. Experiment 3 demonstrated that an X-shock association established after initial A--~X training can be extinguished by nonreinforced presentations of A. These results suggest that associatively evoked representations of stimuli can enter into associations. In standard demonstrations of sensory preconditioning (e.g., Prewitt, 1967), subjects are given an initial phase of training with a serial compound event X-A, neither of the components of which has any marked motivational significance or response-eliciting power. In a second phase of training, one of the elements of the compound (A) undergoes standard Pavlovian training and, by virtue of its association with a motivationally significant unconditioned stimulus (US), comes to evoke an overt conditioned response (CR). In the final, test, phase of the procedure it is demonstrated that Stimulus X is also capable of evoking the CR. This result has been interpreted in terms of the formation of an association between X and A during the first phase of training. The second phase establishes an A-US association so that presentation of the X stimulus at test is able to contact the representation of the US (and thus evoke the CR) by way of the associative chain X-A-US. In addition, the effect can be found when A and X are presented as a simultaneous compound (e.g., Brogden, 1939; Rescorla & Freberg, 1978); in this case too, an excitatory X-A association could still be formed and might be responsible for the result observed. The remaining temporal arrangement (the backward case), in which A precedes the presentation of X, has been little studied; and to the extent that this procedure is less likely to generate the excitatory X-A association, it might be supposed that it would be unlikely to yield a sensory preconditioning effect. Indeed, with one exception, studies that have used backward pairings (i.e., A-X) in the first phase of training have failed to find any effect (Brown & King, 1969; Coppock, 1958; Tait, Marquis, Williams, Weinstein, & Suboski, 1969).

Successive Negative Contrast Effects for Activity-Conditioned Goldfish (Carassiusauratus) as a Function of Housing Conditions

Young goldfish were individually housed in large containers (Part 1), individually housed in small containers (Part 2), or housed in large containers in groups of five (Part 3). The fish were run in sets of five fish (five fish simultaneously in an activity-conditioning chamber). Thus, the fish had to compete for the large or small US that was dropped in the water following a 10-sec. CS (light). Fish in each part comprised groups LS (large US in the first phase of training and small US in the second phase of training), LL, SL and SS. All LS groups showed downward shifts in activity and negative contras effects (lower activity levels than SS control fish). None of the SL groups produced complete upward shifts in activity. Group-housed fish in Part 3 showed larger increases in activity to the CS than individually housed fish in Parts 1 and 2.

Loss of associability by a compound stimulus comprising excitatory and inhibitory elements.

In each of two experiments rats learned a discrimination between a stimulus (A) that signaled shock and a compound stimulus (AB) that signaled no shock. In Experiment 1 it was found that the AB compound acquired excitatory strength only slowly when, in a second phase of training, it was made to signal the occurrence of shock. In Experiment 2 the acquisition of inhibitory strength by the compound was similarly found to be retarded. This second experiment also replicated the results of Experiment 1. The relevance of these results to current theories of latent inhibition and attention is discussed.