When Time Shifts the Boundaries: Isolating the Role of Forgetting in Children's Changing Category Representations.

In studies of children's categorization, researchers have typically studied how encoding characteristics of exemplars contribute to children's generalization. However, it is unclear whether children's internal cognitive processes alone, independent of new information, may also influence their generalization. Thus, we examined the role that one cognitive process, forgetting, plays in shaping children's category representations by conducting three experiments. In the first two experiments, participants (NExp1=37, Mage=4.02 years; NExp2=32, Mage=4.48 years) saw a novel object labeled by the experimenter and then saw five new objects with between one and five features changed from the learned exemplar. The experimenter asked whether each object was a member of the same category as the exemplar; children saw the five new objects either immediately or after a five-minute delay. Children endorsed category membership at higher rates at immediate test than at delayed test, suggesting that children's category representations became narrower over time. In Experiment 3, we investigated forgetting as a key mechanism underlying the narrowing found in Experiments 1 and 2. We showed participants (NExp3=34, Mage=4.20 years) the same exemplars used in Experiments 1 and 2; then, either immediately or after a five-minute delay, we showed children seven individual object features and asked if each one had been part of the exemplar. Children's accuracy was lower after the delay, showing that they did indeed forget individual features. Taken together, these results show that forgetting plays an important role in changing children's newly-learned categories over time.

Does the public know what researchers know? Perceived task difficulty impacts adults' intuitions about children's early word learning.

The present study examined adults' understanding of children's early word learning. Undergraduates, non-parents, parents, and Speech-Language Pathologists (N = 535, 74% female, 56% White) completed a survey with 11 word learning principles from the perspective of a preschooler. Questions tested key principles from early word learning research. For each question, participants were prompted to select an answer based on the perspective of a preschooler. Adults demonstrated aligned intuitions for all principles except those derived from domain-general theories, regardless of experience with language development (Experiment 1). Experiment 2 revealed that perceived difficulty of a task for a preschooler impacted adults' reasoning about word learning processes. Experiment 3 ruled out level of confidence and interest as mechanisms to explain the results. These results highlight disconnects in knowledge between the cognitive development research community and the general public. Therefore, efforts must be made to communicate scientific findings to the broader non-academic community, emphasizing children's ability to excel at word learning in the face of task difficulty.

Not all is forgotten: Children's associative matrices for features of a word learning episode.

Word learning studies traditionally examine the narrow link between words and objects, indifferent to the rich contextual information surrounding objects. This research examined whether children attend to this contextual information and construct an associative matrix of the words, objects, people, and environmental context during word learning. In Experiment 1, preschool-aged children (age: 3;2-5;11 years) were presented with novel words and objects in an animated storybook. Results revealed that children constructed associations beyond words and objects. Specifically, children attended to and had the strongest associations for features of the environmental context but failed to learn word-object associations. Experiment 2 demonstrated that children (age: 3;0-5;8 years) leveraged strong associations for the person and environmental context to support word-object mapping. This work demonstrates that children are especially sensitive to the word learning context and use associative matrices to support word mapping. Indeed, this research suggests associative matrices of the environment may be foundational for children's vocabulary development.

Western-style diet induces object recognition deficits and alters complexity of dendritic arborization in the hippocampus and entorhinal cortex of male rats.

OBJECTIVE: Research demonstrates a link between diet-induced obesity and cognitive impairments; however, no studies have utilized the Sholl analysis to assess changes in dendritic arborization as a possible cause of obesity-induced memory deficits. Therefore, the purpose of this study was to examine the effect of a Western-style diet (WSD) on memory and dendritic complexity of male Sprague-Dawley rats. METHODS: Male Sprague-Dawley rats (n = 18) were fed either a control or WSD. Spatial memory and episodic memory were assessed using the Morris Water Maze and novel object recognition (NOR) tasks, respectively. At termination, brains were removed and prepared with the Golgi-Cox method. Stained neurons in both the hippocampus and entorhinal cortex (EC) were imaged and digitally reconstructed. RESULTS: Results indicated significant differences in percent body fat and TNFα levels between dietary conditions. WSD males also experienced reduced NOR exploration ratios, but no deficits in spatial memory were observed. Analysis of dendritic length and number of branch points revealed no significant differences in either the EC or the hippocampus; however, the Sholl analysis indicated that a WSD increased neuronal complexity in the EC. DISCUSSION: Sholl analysis of the EC suggests a possible diet-induced dysfunction of pruning, which may contribute to reduced performance on the NOR task. Elevated TNFα levels indicate a putative role of inflammation in neuronal remodeling. The results demonstrate the importance of investigating mechanisms underlying obesity-related cognitive impairments.