Constructing informative model priors using hierarchical methods

Despite their negative reputation, informative priors are very useful in inference. Priors that express psychologically meaningful intuitions damp out random fluctuations in the data due to sampling variability, without sacrificing flexibility. This article focuses on how an intuitively satisfying informative prior distribution can be constructed. In particular, it demonstrates how the hierarchical introduction of a parameterized generative account of the set of models under consideration naturally imposes a non-uniform prior distribution over the models, encoding existing intuitions about the models. The hierarchical approach for constructing informative model priors is made concrete using a worked example, the Varying Abstraction Model (VAM), a family of categorization models including and expanding the exemplar and prototype models. It is shown how psychological intuitions about the relative plausibilities of the models in the VAM can be formally captured in an informative prior distribution over these models, by specifying a theoretically informed process for generating the models in the VAM. The smoothing effect of the informative prior in estimation is demonstrated by considering ten previously published data sets from the category learning literature.     

Development of implicit and explicit category learning

We present two studies that examined developmental differences in the implicit and explicit acquisition of category knowledge. College-attending adults consistently outperformed school-age children on two separate information-integration paradigms due to children’s more frequent use of an explicit rule-based strategy. Accuracy rates were also higher for adults on a unidimensional rule-based task due to children’s more frequent use of the irrelevant dimension to guide their behavior. Results across these two studies suggest that the ability to learn categorization structures may be dependent on a child’s ability to inhibit output from the explicit system.     

Word fluency performance and strategies in children with cochlear implants: age‐dependent effects?

Löfkvist, U., Almkvist, O., Lyxell, B. & Tallberg, I.‐M. (2012). Word fluency performance and strategies in children with cochlear implants: age‐dependent effects? Scandinavian Journal of Psychology 53, 467–474. Word fluency was examined in 73 Swedish children aged 6–9 years divided into two age groups, 6–7 and 8–9 years; 34 deaf children with cochlear implants (CI) (15 girls/19 boys) and 39 age‐matched children with normal hearing (NH) (20 girls/19 boys). One purpose was to compare the ability to retrieve words in two different word fluency tasks; one phonemically based (FAS letter fluency) and one semantically based (animal fluency). A second purpose was to examine retrieval strategies in the two tasks by conducting an analysis of clustering and switching of word sequences. In general we found that age was an important factor for word fluency ability, in both the CI and the NH groups. It was also demonstrated that children with CI aged 8–9 years retrieved significantly fewer words and used less efficient strategies in the retrieval process, especially on the phonemically based task compared to children with NH of the same ages, whereas children 6–7 years performed similarly in both groups regarding number of retrieved words and use of strategies. The results are discussed with respect to factors such as age differences in performance for children with CI, especially for the phonemically based task.     

Functional near-infrared spectroscopy for the assessment of speech related tasks

Over the past years functional near-infrared spectroscopy (fNIRS) has substantially contributed to the understanding of language and its neural correlates. In contrast to other imaging techniques, fNIRS is well suited to study language function in healthy and psychiatric populations due to its cheap and easy application in a quiet and natural measurement setting. Its relative insensitivity for motion artifacts allows the use of overt speech tasks and the investigation of verbal conversation. The present review focuses on the numerous contributions of fNIRS to the field of language, its development, and related psychiatric disorders but also on its limitations and chances for the future.     

Neural correlates of acquired color category effects

Category training can induce category effects, whereby color discrimination of stimuli spanning a newly learned category boundary is enhanced relative to equivalently spaced stimuli from within the newly learned category (e.g., categorical perception). However, the underlying mechanisms of these acquired category effects are not fully understood. In the current study, Event-Related Potentials (ERPs) were recorded during a visual oddball task where standard and deviant colored stimuli from the same or different novel categories were presented. ERPs were recorded for a test group who were trained on these novel categories, and for an untrained control group. Category effects were only found for the test group on the trained region of color space, and only occurred during post-perceptual stages of processing. These findings provide new evidence for the involvement of cognitive mechanisms in acquired category effects and suggest that category effects of this kind can exist independent of early perceptual processes.     

“右好左坏”和“左好右坏”——利手与左右空间情感效价的关联性

人们会将“右”和“左”与积极或消极的事物相关联,这称为左右空间的情感效价.以具身认知理论和躯体特异性假设为基础的研究发现,右利手会将右侧空间与积极事物相关联,而左利手则会将左侧空间与积极事物相关连;左右空间情感效价是由利手与非利手的运动经验塑造的;利手与非利手运动经验的改变则会反转左右空间情感效价;趋近动机脑功能偏侧化与利手是一致的.未来的研究应进一步澄清利手运动与趋近动机在神经机制上的关联性,并探索文化因素与身体经验如何共同塑造左右空间情感效价.     

加工流畅性的作用机制：双系统模型及其应用

加工流畅性在近二十年来引发了大量的研究,这些研究对人们深入了解认知-情绪的相互作用机制很有价值,与决策、直觉、审美等领域的研究也有密切的关系。流畅性-归因模型和流畅性-情绪联结模型是解释加工流畅性效应的两个竞争模型,笔者分析与评价了这两个模型的观点与证据,提出了建立双系统模型的初步设想,并对未来如何根据双系统模型的观点进一步开展加工流畅性的作用机制研究进行了展望。     

Learning about the internal structure of categories through classification and feature inference

Previous research on category learning has found that classification tasks produce representations that are skewed toward diagnostic feature dimensions, whereas feature inference tasks lead to richer representations of within-category structure. Yet, prior studies often measure category knowledge through tasks that involve identifying only the typical features of a category. This neglects an important aspect of a category's internal structure: how typical and atypical features are distributed within a category. The present experiments tested the hypothesis that inference learning results in richer knowledge of internal category structure than classification learning. We introduced several new measures to probe learners' representations of within-category structure. Experiment 1 found that participants in the inference condition learned and used a wider range of feature dimensions than classification learners. Classification learners, however, were more sensitive to the presence of atypical features within categories. Experiment 2 provided converging evidence that classification learners were more likely to incorporate atypical features into their representations. Inference learners were less likely to encode atypical category features, even in a “partial inference” condition that focused learners' attention on the feature dimensions relevant to classification. Overall, these results are contrary to the hypothesis that inference learning produces superior knowledge of within-category structure. Although inference learning promoted representations that included a broad range of category-typical features, classification learning promoted greater sensitivity to the distribution of typical and atypical features within categories.     

Default spacing is the optimal spacing for word reading

Increased interletter spacing is thought to reduce crowding effects and to enhance fluent reading. Several studies have shown beneficial effects of increased interletter spacing on reading speed and accuracy, especially in poor readers. Therefore, increased interletter spacing appears to be a relatively easy way to enhance reading performance. However, in adult readers reading speed was shown to be impeded with increased interletter spacing. Thus, findings on interletter spacing are still inconclusive. In the current study we examined the effect of a range of interletter spacings (?0.5, default, 0.5, 1, 1.5, 2) on naming fluency of monosyllabic and bisyllabic words in beginning (Grade 2) and more advanced (Grade 4) readers. Additionally we tested the effects of spacing in a subsample of poor readers. In contrast to previous findings, neither beginning nor advanced readers benefited from an increase in interletter spacing. However, they did show reduced reading fluency when letter spacing was smaller than the default spacing, which may be indicative of a crowding effect. Poor readers showed a similar pattern. We conclude that an increase in interletter spacing has no effect on word naming fluency.     

The temporal locus of the categorical bias in spatial memories

People often use the region of a target's location to make judgements about its exact position. Although there is general agreement that this category-based effect is due to a blending of the specific coding of a target's location and the categorical coding of its region, there is little agreement on when the blending occurs. The current paper examines whether the systematic bias is the result of combining separate undistorted mental representations at the time of retrieval or a result of using a category-distorted mental representation. Participants studied a dot within a circle and reproduced its location from memory after a short or long delay, and new categorical information was introduced during target retrieval. The results showed a larger increase over time in the biases caused by the new category introduced at retrieval than in the biases caused by the originally encoded category. The findings are consistent with retrieval models, providing evidence that category biasing processes operate at the time of memory retrieval.