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The effects of estradiol on avoidance learning in ovariectomized adult rats.

The present study examined the effects of ovariectomy and subsequent estradiol replacement on learning in young adult rats using a set of instrumental avoidance paradigms differing in the nature and extent of prior experience in the learning context. Thus, one group of animals was placed directly into avoidance learning (AV). A second group was trained on an appetitive task first, and then transferred into the aversive context (AP-AV). The third group was exposed to the training context without any specific appetitive response requirement, and then required to learn an active avoidance response (Context-AV). We found that estradiol (OVX+E) impaired avoidance acquisition in all cases relative ovariectomized controls (OVX). In contrast, while avoidance learning is improved following appetitive training or context exposure in both OVX+E and OVX animals, the OVX+E animals profit to a greater extent from the appetitive or context experience than do the OVX controls. We suggest that this difference may be due to enhanced attentional processes or improved hippocampal processing of contextual factors. Thus, estradiol negatively influences simple associative avoidance learning in ovariectomized rats, but appears to promote positive transfer.

Animals↗
PubMed1996

[Texture discrimination and visual search: development, learning and plasticity].

BACKGROUND: The abilities to segment coherent surfaces out of a discrepant background (texture segmentation) and to localize single objects out of a complex scene (visual search) are believed to occur at a peripheral level in the cortical visual pathway. AIM OF THE STUDY: Are texture segmentation and visual search innate or acquired? Can these abilities be improved in adulthood by learning? Does a disturbed early visual experience (strabismus, amblyopia) lead to a reduction of these abilities? RESULTS: Texture segmentation and visual search undergo a protracted development which continues well into adulthood. Even in adult observers, these abilities can be improved with practice. Learning is enduring, but not specific: It can be transferred from one task to another and between the two eyes of a given subject (including the two eyes of stereoblind subjects). DISCUSSION: We conclude that learning of texture segmentation and visual search does not involve the specific features of a visual scene, but rather reflects an improved strategy of localizing visual objects in a cluttered environment. This type of learning probably occurs at a very high level of cortical processing.

Adolescent↗
PubMed1995

Effects of lags on human operator transfer functions with head-coupled systems.

The effects of operator learning and target velocity on head tracking performance with and without lags has been studied. Five lags (0, 40, 80, 120, 160 ms) between head movement and target image movement, and three target velocities (2, 3.5, 5 degrees.s-1 r.m.s.) were investigated with eight male subjects and band-limited random target motions. Head tracking transfer functions, tracking error spectra, mean radial tracking error, and subjective difficulty ratings were obtained. Head tracking performance was significantly degraded by lags greater than, or equal to, 40 ms (in addition to a system lag of 40 ms). Both the input-correlated tracking error and the uncorrelated tracking error increased with increasing lag. No significant improvement in head tracking performance was found through practice with an 80-ms lag. As the lag increased, operators increased their gains at frequencies above about 0.5 Hz and reduced their phase lags at low frequencies (about 0.1 Hz) but failed to fully compensate for the increased display lag. The increased human operator gain was associated with increased operator phase lag at higher frequencies (above 0.5 Hz). To improve head tracking performance in the presence of lags, a lag compensation technique is needed to prevent undesirable changes in tracking strategy.

Aerospace Medicine↗
PubMed1985

Attention to multiple cues by severely mentally retarded adults: effects of single-component pretraining.

The present investigation examined whether the amount of compatible single-element training affected response accuracy for conditional-discrimination tasks requiring attention to multiple cues. Four severely mentally retarded adults participated, and a multiple baseline across subjects and reversal design was employed. Following acquisition of conditional discriminations by individually training each stimulus element, transfer tests were provided. In the first transfer condition, two intermixed conditional-discrimination tasks were presented containing identical stimuli to those individually trained. The second transfer condition consisted of two intermixed conditional-discrimination tasks composed of novel S- stimuli and pretrained S+ stimuli. Finally, a control procedure was administered in which conditional-discrimination tasks contained all untrained cues. The severely mentally retarded subjects did learn to respond to multiple cues. Establishing separate control by each component produced attention to two aspects of compound stimuli with few errors occurring. In addition, these broadened attentional skills generalized to multistimulus tasks containing all or some of the original pretrained stimuli. If single-element training was omitted, performance on conditional-discrimination tasks was greatly impaired.

Adult↗
PubMed1998

Assessing olfactory performance in an Old World primate, Macaca nemestrina.

The present study demonstrates that an operant conditioning paradigm, originally designed for assessing olfactory performance in a small New World primate, the squirrel monkey, can successfully be adapted for use with a large Old World primate, the pigtail macaque. Using a task designed to simulate olfactory-guided foraging behavior, based on multiple discrimination of simultaneously presented odor stimuli, we could show that Macaca nemestrina is able to learn to discriminate between objects on the basis of odor cues. Moreover, they could readily transfer to new S+ and S- stimuli and could remember the significance of previously learned odor stimuli even after a 3-week break. Furthermore, we could show that this method is suitable for obtaining reliable measures of olfactory sensitivity. The few modifications of the original method employed here did not affect essential features such as the mode of stimulus presentation (odorized paper strips attached to manipulation objects) and the choice criterion (opening or rejecting the odorized manipulation objects), thus for the first time enabling valid interspecific comparisons of olfactory capabilities between a catarrhine and a platyrrhine primate species. Our results indicate that M. nemestrina and Saimiri sciureus are similar with regard to several measures of olfactory performance, such as speed of initial task acquisition and ability to master transfer tasks as well as their sensitivity to a food-related odorant.

Animals↗
PubMed1998

Concurrent administration of subeffective doses of scopolamine and MK-801 produces a short-term amnesia for the elevated plus-maze in mice.

Amnesic properties of scopolamine, a muscarinic receptor antagonist, and MK-801, a non-competitive N-methyl-D-aspartate (NMDA) receptor antagonist, were evaluated in mice by means of the elevated plus-maze test. In this test, transfer latency, the time mice took to move from the open arm to the enclosed arm, was used as an index of learning and memory. The 3-day pretreatment training dramatically decreased transfer latencies. On the 4th day, the retention trial was performed 30 min after the intraperitoneal injection of scopolamine (Experiment 1) or MK-801 (Experiment 2). The doses of 0.25 and 0.5 mg/kg of scopolamine as well as the doses of 0.1, 0.15, 0.2 and 0.4 mg/kg of MK-801 significantly prolonged the transfer latency as compared with both that in the saline-treated group and that measured on the 3rd day. In Experiment 3, subthreshold doses of these two drugs given in combination (which were ineffective when given alone: scopolamine 0.25 mg/kg, MK-801 0.075 mg/kg) significantly prolonged the transfer latency on the fourth day. However, an amnesic effect of scopolamine plus MK-801 was transient. On the 5th day, no differences in the transfer latency were found. This finding clearly indicates that there is a close relationship between cholinergic and glutamatergic systems and that both systems play an important role in a spatial orientation of mice on the elevated plus-maze.

Amnesia↗
PubMed2003

Successful acquisition of an olfactory discrimination paradigm by spider monkeys, Ateles geoffroyi.

The present study demonstrates that an operant conditioning paradigm-originally designed for assessing olfactory performance in an Old World primate, the pigtail macaque-can successfully be adapted for use with a New World primate, the spider monkey. Using a task based on a food-rewarded, two-choice discrimination of simultaneously presented odor stimuli, Ateles geoffroyi is capable of learning to discriminate between objects on the basis of odor cues. Moreover, animals could readily transfer to new S+ and S- stimuli, and could remember the significance of previously learned odor stimuli even after a 4-week break. We could also show that this method is suitable for obtaining reliable measures of olfactory sensitivity. Our results indicate that A. geoffroyi clearly outperforms Macaca nemestrina with regard to the speed of initial task acquisition and the ability to master transfer tasks, and shows a sensitivity to a food-related odorant which matches that of other primate species.

Animal Feed↗
PubMed1982

Interhemispheric transfer of visual pattern discriminations: evidence for a bilateral storage of the engram.

The present experiment was carried out to determine whether the memory trace of a pattern discrimination learned with one hemisphere is also transmitted to the second hemisphere via the corpus callosum or whether the trace is limited to the trained hemisphere and becomes accessible to the second during recall via this route. Split-chiasma cats learned two pattern discriminations with one eye (and hemisphere), then were subjected to a mid-sagittal transection of their corpus callosum, followed by learning with the other untrained eye (and hemisphere). Ten cats were separated into two groups: one group learned the discrimination to criterion (the non-overtrained group) while the other received 1600 overtraining trials over and beyond those needed to reach criterion (the overtrained group). Results indicated that there was little bilateral storage in the non-overtrained group (as determined by the number of trials needed to attain criterion with the second eye). Most subjects from the overtrained group showed chance performance during the first transfer session but learned the pattern discrimination much more rapidly with the second eye than with the first. These results are taken as indicating that memory transcription is possible through the callosum but that this route is slower and its readout is possibly contaminated by secondary non-specific factors which affect the initial utilization of the trace.

Animals↗
PubMed1984

Structured experience: a risk-free approach to reality-based learning.

The structured experience facilitated learning in an emotionally charged situation by reducing risk factors and the participants' anxieties. It also facilitated discussing and sharing ideas and feelings. The simple format of the Land of Suria enabled not only health care deliverers or students but also experts to learn at their levels of awareness. The learners were able to transfer the knowledge gained from the structured experience to real-life situations. The writer believes that the structured experience can be utilized as a risk-free method of learning prior to potential anxiety-producing situations (i.e., C.C.U., acute psychiatric crises, transcultural situations, etc.) and that the resulting knowledge can be effectively transferred to anxiety-producing, real-life situations. The structured experience is not open-ended for the students to totally define out of their own experience. It is structured to include content and process which the instructor deems valuable. Specific nursing situations can be designed with outcomes predictable within a given range of behaviors. Many variables determine choices of nurses' behaviors, and the structured experience allows the student to bring past learning to the situation and examine what they did, how they did it, why they did it, and how they feel about it. Because the structured experience is learning that encompasses both the cognitive and affective domain, it has the potential of greater impact upon the learner and a greater potential for transfer and retention.(ABSTRACT TRUNCATED AT 250 WORDS)

Education, Nursing↗
PubMed1996

Adult auditory learning and training.

We describe a theoretical framework that distinguishes stimulus, procedural, and task aspects of learning, and we suggest that this framework may allow an improved understanding of acclimatization and late-onset auditory deprivation. We review the literature on learning after sensorineural hearing loss and after the provision of amplification. We then examine the possibility of using training to improve the speech-understanding skills of listeners with sensorineural hearing loss after provision of amplification. Here, we concentrate on techniques recently demonstrated to encourage the acquisition of non-native phonetic contrasts in second-language learners. We argue that there are three general principles associated with auditory learning and training: 1) the more complex the task, the longer the learning period required; 2) the greater the similarity between training and test tasks, the greater the transfer of training; and 3a) the more familiar the stimulus materials, the faster the subsequent learning. When training for speech identification in everyday life, maximizing the opportunity for the listener to cope with the acoustic variability found in natural speech, both within and between talkers, is important. We, therefore, argue that the third principle should be extended: 3b) the more the training set exemplifies the acoustic variability found within and between talkers, the greater the transfer to open-set speech identification in everyday life. Throughout the review, we show that individual differences in learning are observed in the rate of acquisition and in the level of asymptotic performance. We argue that it is possible to postulate modulators of learning that may account for some of these individual differences. Possible candidates for influential modulators are: 1) the history of hearing impairment--the longer the history, the longer the time taken to improve performance and, possibly, the lower the asymptotic level of performance; 2) the severity and pattern of hearing loss; 3) the degree of asymmetry in the hearing loss and its effect on the binaural organization of the hearing system; and 4) the level of patient adaptability and cognitive abilities, such as attentional control and short-term memory span.

Cognition↗
PubMed1996

The working self-concept in transference: significant-other activation and self change.

This research tested the hypothesis that changes in the working self-concept emerge in transference, defined as the activation and application of a significant-other representation to a new person and indexed by relevant inferences and memory (e.g., S. M. Andersen & A. Baum, 1994; S. M. Andersen, N. S. Glassman, S. Chen, & S. Cole, 1995). In an idiographic-nomothetic design, participants learned of a target person who resembled their own or a yoked participant's positively or negatively toned significant other. Results replicated the basic memory effect verifying transference. As predicted, the working self-concept changed in the transference condition. After learning about the new person, participants' freely listed self features shifted; the working self-concept became more infused with aspects of the self reflecting the self when with this significant other. Relevant changes in self evaluation were observed. Hence, changes in the working self-concept occurred in transference.

Analysis of Variance↗
PubMed2001

Predicting transfer from training performance.

The research in this paper was designed to examine the extent to which improvement on a training task can be used to predict performance on a transfer task. This aim involved evaluating the proposition that when old skills are executed in the context of new tasks, they continue to improve as if stimulus conditions have not changed. That is, power functions that describe improvement on old skills during their initial acquisition should predict further improvement on these skills during their execution in new tasks. Three experiments were performed to achieve the aim of testing this proposition. Experiment 1 revealed that old skills were executed slower in the context of a new task than was predicted on the basis of training performance. Hence improvement in the old skills appeared to be disrupted by performance of the new task. Experiment 2 was designed to examine whether this disruption was due to an increase in complexity in the task from training to transfer, or simply due to any change in task. The results suggested that any change may cause some disruption, but this disruption was greatest with an increase in task complexity. Experiment 3 was designed to examine two variables that may affect the magnitude of this effect: the relative change in task complexity from training to transfer, and the amount of practice on a task prior to a change in task. The results indicated that only the former variable had any effect. In all three experiments no effects on performance accuracy were noted, and response times in the transfer tasks eventually returned to levels predicted by training learning functions. These results were interpreted as indicating that old skills do continue to improve in new tasks as if conditions are not altered, but that disruptions caused by transfer are related to performance overheads associated with reconceptualising the task.

Adult↗
PubMed2006

Exemplar effects in the context of a categorization rule: Featural and holistic influences.

Brooks and colleagues (S. W. Allen & L. R. Brooks, 1991; G. Regehr & L. R. Brooks, 1993) have shown that the classification of transfer stimuli is influenced by their similarity to training stimuli, even when a perfect classification rule is available. It is argued that the original effect obtained by Brooks and colleagues might have resulted from two potential confounding variables. Once these confounds were controlled, the current authors did not replicate Brooks and colleagues' results in Experiment 1. Exemplar effects appeared in Experiment 2 when transfer stimuli were perceptually more similar to training stimuli than in Experiment 1. In Experiment 3, the authors obtained exemplar effects with separated stimuli, a finding that was not predicted by Brooks and colleagues' model. The authors suggest that a close perceptual match between training and transfer stimuli is necessary for the effect to occur, for both integrated and separated stimuli. The nature of this perceptual match, holistic or featural, is discussed.

Association Learning↗
PubMed2006

Human adaptation to interaction forces in visuo-motor coordination.

We tested whether humans can learn to sense and compensate for interaction forces in contact tasks. Many tasks, such as use of hand tools, involve significant interaction forces between hand and environment. One control strategy would be to use high hand impedance to reduce sensitivity to these forces. But an alternative would be to learn feedback compensation for the extrinsic dynamics and associated interaction forces, with the potential for lower control effort. We observed subjects as they learned control of a ball-and-beam system, a visuo-motor task where the goal was to quickly position a ball rolling atop a rotating beam, through manual rotation of the beam alone. We devised a ball-and-beam apparatus that could be operated in a real mode, where a physical ball was present; or in a virtual training mode, where the ball's dynamics were simulated in real time. The apparatus presented the same visual feedback in all cases, and optionally produced haptic feedback of the interaction forces associated with the ball's motion. Two healthy adult subject groups, vision-only and vision-haptics (each n= 10), both trained for 80 trials on the simulated system, and then were evaluated on the real system to test for skill transfer effects. If humans incorporate interaction forces in their learning, the vision-haptics group would be expected to exhibit a smoother transfer, as quantified by changes in completion time of a ball-positioning task. During training, both groups adapted well to the task, with reductions of 64%-70% in completion time. At skill transfer to the real system, the vision-only group had a significant 35% increase in completion time (p < 0.05). There was no significant change in the vision-haptics group, indicating that subjects had learned to compensate for interaction forces. These forces could potentially be incorporated in virtual environments to assist with motor training or rehabilitation.

Adaptation, Physiological↗
PubMed1982

Negative transfer abolished by REM sleep deprivation in rats.

Brief deprivation of REM sleep (REMD) immediately following inhibitory avoidance training abolished negative transfer in an active avoidance situation without impairing retention of the inhibitory avoidance response. REMD beginning 3 hr after inhibitory training had no effect. A reminder treatment (brief placement in the apparatus) between 30 min and 24 hr before active avoidance training counteracted the REMD impairment of negative transfer. The reminder treatment was not impaired by subsequent REMD.

Animals↗
PubMed1994

Discrimination of artificial polymorphous categories by rhesus monkeys (Macaca mulatta).

Monkeys (Macaca mulatta) were trained to discriminate between sets of artificial stimuli such as those used by Jitsumori (1993) for pigeons and humans. The stimuli were arrays of symbols differing along three two-valued (positive or negative) dimensions. The discrimination required was between polymorphous categories in which a positive stimulus was defined by possession of any 2 out of 3 positive features. Of the 5 monkeys, 3 learned the discrimination much faster than did pigeons, but transfer to novel stimuli was less impressive than had been shown in pigeons. The 3 monkeys showed high levels of transfer to the stimuli that contained either all 3 positive or all 3 negative features, but 2 of the 3 monkeys failed to show transfer to stimuli that had 1 of the 3 features replaced with a novel one. Analysis of the monkeys' performance raised doubts on the additive integration of features but supported learning of feature combinations as a basis for the discrimination of polymorphous categories by this species.

Animals↗