The effect of stimulus preexposure upon the context effect in taste-aversion learning in noradrenaline-depleted rats

The present investigation was designed to study the effect of preexposure to a saccharin plus noisy bottle stimulus compound, or to each element by itself, upon the extinction-dependent "context effects" (due to the presencelabsence of the noisy bottle contextual cue) in taste-aversion learning, following noradrenaline (NA) depletion via a single systemic DSP4 injection. Since contextual manipulations have provided a reliable means of studying selective attentional processes the current theorising on the role of noradrenaline can be effectively accommodated. It was found that, under the No Preexposure and Noisy Bottle Preexposure conditions, the "context effect" during the saccharin preference tests, after reinstatement of the noisy bottles for all groups, was totally absent for the NA-depleted rats; in the Saccharin plus Noisy Bottle Preexposure condition the "context effect" was partially blocked for the NA depleted rats and in the Saccharin Preexposure condition it was at least as strong as in the control condition, These findings may be interpreted as supporting our conclusions, concerning NA-depleted rats derived from several different investigations, i.e. that following NA loss rats fail to attend sufficiently to contextual cues in taste-neophobia and taste-aversion situations. Thus, the attentional deficit may be described as an inability to attend to all aspects of the taste stimulus plus exteroceptive context stimulus compound. Although the selective attentional hypothesis of noradrenaline function requires a good deal of alteration, it remains the most parsimonious account that can be described at present.     

The effect of context variability on motor learning

Although the practice schedule and variation in incidental context have been investigated together, it is not clear whether just variation in incidental context can beneficiate motor learning. Therefore, the present study aimed to investigate the effect of context variability on motor learning. We hypothesized the practice in a variable incidental context would enable learners to be more resistant to the effects of the contextual changes when compared to a constant incidental context practice. Twenty-four participants were assigned to one of the two groups: constant incidental context (G_CC) or variable incidental context (G_VC). During practice, the G_CC practiced a sequence keypressing task in one color and a position showed on the computer screen. The G_VC practiced the same sequence in four different combinations of color and position. Twenty four hours, the same contexts practiced on practice (SAME) was performed and immediately after, a new sequential movement in new color and new position (SWITCH) was performed. The results indicated that the G_VC showed better performance than the G_CC on the SWITCH condition, mainly in measures related to planning/selection process. The results were explained by degree of similarity among processing events engaged during different moments and by development of a filter of information based on attentional selection.     

Procedural learning in schizophrenia: further consideration on the deleterious effect of neuroleptics

Deficits in procedural learning remain a controversial issue in schizophrenia. This may be related to the nature of the neuroleptic treatment of schizophrenic patients as conventional neuroleptics may be more deleterious than new atypical neuroleptics. However, there is no comparative study on the effect of specific neuroleptics on procedural learning. In this study, three groups of patients treated with different neuroleptics were compared to normal controls on two procedural learning tasks. In a visuo-motor task, patients and controls showed similar learning rates, although schizophrenic patients showed generally lower performances than normal controls. However, patients treated with a conventional neuroleptic, but not those treated with the atypical neuroleptics, showed many fluctuations during the initial learning phase. In a problem-solving task, all groups were comparable in performance and learning fluctuations, but learning rates were lower in patients treated with the neuroleptic showing the higher incidence of extrapyramidal symptoms. This suggests that procedural learning abilities may be significantly affected by neuroleptics in schizophrenia, although the effect may differ between tasks and the specific neuroleptics. Fluctuations in the initial learning phase of the visuo-motor task probably results from a frontal dysfunction while reduced learning rates, such as those observed in the problem solving task, may be attributed to a striatal dysfunction. This is concordant with the differential pharmacological actions of the conventional and atypical neuroleptics in these two cerebral areas.     

Analysis of the perceptual learning effect in flavour aversion learning: Evidence for stimulus differentiation

Rats received exposure to two compound flavours, AX and BX, where A and B were sucrose and saline and X was acid. For group intermixed (I), exposure consisted of alternating trials with AX and BX; group blocked (B) received a block of AX trials and a separate block of BX trials. Experiment 1 showed that generalization to BX after conditioning with AX was less profound in group I than in group B. Separate examination of the elements of the compound showed that the source of this difference lay in the strength acquired by the X element. X acquired less strength in group I than in group B (Experiments 1 and 2), whereas for the A element (Experiments 3 and 4) the reverse pattern was obtained. These results support the proposal that the perceptual learning effect (restricted generalization from AX to BX in group I) depends on a process that enhances the effectiveness of unique stimulus elements (A and B) and reduces that of common elements (such as X).     

Intertrial interval as a contextual stimulus: further analysis of a novel asymmetry in temporal discrimination learning

Four experiments investigated discrimination learning when the duration of the intertrial interval (ITI) signaled whether or not the next conditional stimulus (CS) would be paired with food pellets. Rats received presentations of a 10-s CS separated half the time by long ITIs and half the time by short ITIs. When the long ITI signaled that the CS would be reinforced and the short interval signaled that it would not be (Long+/Short-), rats learned the discrimination readily. However, when the short ITI signaled that the CS would be reinforced and the long interval signaled that it would not (Short+/Long-), discrimination learning was much slower. Experiment 1 compared Long+/Short- and Short+/Long- discrimination learning with 16-min/4-min or 4-min/1-min ITI combinations. Experiment 2 found no evidence that Short+/Long- learning is inferior because the temporal cue corresponding to the short interval is ambiguous. Experiment 3 found no evidence that Short+/Long- learning is poor because the end of a long ITI signals a substantial reduction in delay to the next reinforcer. Long+/Short- learning may be faster than Short+/Long-because elapsing time involves exposure to a sequence of hypothetical stimulus elements (e.g., A then B), and feature-positive discriminations (AB+/A-) are learned quicker than feature-negative discriminations (A+/AB-). Consistent with this view, Experiment 4 found a robust feature-positive effect when sequentially presented CSs played the role of elements A and B.     

The genetic context of perceptual imprinting: Canalization by stimulus preference

Recent data from various sources converge in pointing to constitutional constraints and genetic influences in behavioral development. What are the mechanisms that mediate such constraints and influences? Are they expressed through mechanisms of behavior acquisition and learning? Or are they expressed through genetically determined perceptual capacities and response propensities that guide behavior along species-typical and ontogenetically adaptive developmental trajectories? These alternatives are examined in the context of genetically and environmentally manipulated stimulus preferences and perceptual imprinting in Japanese quail chicks (Coturnix coturnix japonica). Data indicate that the genotype is a source of variation in unconditional stimulus preferences and that there are inhibitory and facilitative interactions between different unconditional preferences and also between unconditional and acquired preferences. Variations in stimulus-specific and stimulus-general learning may guide behavioral development in ways that are genetically preadapted, yet individually variable, and ontogenetically adaptive. Interpretation of data favors a synthesis of earlier psychological and biological concepts of canalization.     

The effect of category learning on the representation of shape: dimensions can be biased but not differentiated

Recent studies have suggested a profound influence of category learning on visual perception, resulting in independent processing of previously integral dimensions. The authors reinvestigate this issue for shape dimensions. They first extend previous findings that some shape dimensions (aspect ratio and curvature) are processed in a separable way, whereas others (radial frequency components) are not. They then show that a category-learning phase improved the discrimination of a relevant with respect to an irrelevant dimension, but only for separable dimensions. No similar effect was found on the relative sensitivity for integral shape dimensions. Thus, category learning is capable of biasing separable shape dimensions but does not alter the status of dimensions in the visual system as either separable or integral.     

The effect of statistical learning on internal stimulus representations: Predictable items are enhanced even when not predicted

Statistical learning is the automatic and unconscious learning of environmental regularities and is a basic mechanism of learning in a variety of human perceptual and cognitive domains. Previous studies have mainly focused on the associative mechanisms of statistical learning. However, an unexplored question is whether the internal representations of individual stimuli are altered as their associations are learned. Using a temporal statistical learning paradigm, we examine this question across three experiments and find clear evidence that the internal representations of individual stimuli are differentially altered according to their degree of temporal predictability. These findings complement previous accounts of statistical learning and reveal an enriched mechanism of human learning, such that learning to associate items also enhances the representations of certain items relative to others.     

The effect of experience on children's ability to show response and place learning

From a developmental perspective, it has been reasoned that over the course of development children make differential use of available landmarks in the surroundings to orient in space. The present study examined whether children can learn to apply different spatial strategies, focusing on different landmark cues. Children aged 7 and 10 years were tested on an object‐location memory task in which they learned a location relative to a direct cue or to indirect cues. Both age groups performed equally well on the direct test condition. However, children 7 years of age had difficulties with orienting relative to the indirect landmarks. Interestingly, their performance increased significantly with more relevant experience. Different explanations for these findings are discussed.     

情境对共情的影响

共情指的是个体在与人交往的过程中共享并理解他人的情绪状态的倾向, 包括认知共情和情绪共情两种成分。现实生活中的共情总是发生在一定的具体情境中, 受到情境因素的影响。其中, 情境的公开性或私密性、意义性等均在不同程度上影响了共情的产生或共情反应的强烈程度。共情对象在特定情境中与共情主体之间的群际关系、人际关系等也是重要的情境因素, 共情主体对于和自己属于同一群体或拥有较亲密人际关系的他人更容易产生共情。情境对共情的影响通过自上而下和自下而上两种方式实现。有关情境对共情的影响研究虽然取得了一定的成果, 但仍然有进一步拓展的空间, 未来的研究需要在情境因素的内涵上进行深入挖掘, 从认知加工的角度对情境影响共情的机制做更为细致、微观地解析, 还可以从共情主体的视角明确个体差异如何调节了情境对共情的影响作用。     

Context learning and the effect of context on memory retrieval in Lymnaea

Aerial respiratory behavior in Lymnaea was operantly conditioned so that the animals perform aerial respiration significantly less often. Using the standard training procedure (pond water made hypoxic by bubbling N₂ through it) both food-deprived and fed animals learned and exhibited long-term memory (LTM). However, food-deprived animals exhibited neither learning nor memory when trained under a condition in which the hypoxic pond water also contained a food odorant (carrot, the food-odorant procedure). Fed animals, however, learned and exhibited LTM with the food-odorant procedure. Thus, the presence of the food odorant per se did not prevent learning or the establishment of LTM. Further experimentation, however, revealed that the ability of the snails to have recall (i.e., memory) for the learned behavior was dependent on the context in which memory was tested. That is, if animals were trained with the food-odorant procedure they could only exhibit recall if tested in the food-odorant context and vice versa with the standard training procedure. Thus, although fed animals could learn and show LTM with either training and testing procedure, LTM could only be seen when they were tested in the context in which they were trained.     

The perception of number from the separability of the stimulus: The Stroop effect revisited

The literature on numerical perception is reviewed from the standpoint of research on selective attention, and predictions are made concerning the dimensional interaction between physical and numerical size of numerals. We manipulated stimulus differences to make the classification of numerical value slightly better (Experiment 1), substantially better (Experiment 2), or worse (Experiments 3–4) than classification of physical size. Garner, Stroop, and redundancy effects were used to gauge the degree of interactive processing. For nearly matched discriminability, both number and size appeared separable when the dimensions were varied orthogonally, but showed Stroop interference and redundancy gain when the dimensions were varied in a correlative fashion. When mismatched, asymmetric Garner and Stroop effects emerged in orthogonal contexts along with Stroop and redundancy gains in correlative contexts. These findings define a unique relation: Numerical value and physical size were optionally separable dimensions. We conclude that a magnitude representation is not mandatory for the perception of numerals. Our conclusions offer a new perspective for understanding both numerical perception and the Stroop phenomenon itself.