Coding strategies,perceptual grouping,and the “variability effect” in free recall

Three experiments examined the effects of constant vs. varied input of letter strings on recall, and then examined the effects of such training in the learning of new lists of letter strings. Letter strings were constructed from pairs of trigrams spatially grouped, and were presented either consistently or with different spatial groupings on successive presentations. In Experiments I and II, varied input produced substantially greater recall than constant input. When transferred to a new list of letter strings, containing either the same general structure or a new scrambled structure, recall of the second list was determined primarily by conditions of first-list input, and unaffected by second-list structure. Although the "variability effect" did not appear in the training phase of Experiment III, Varied input led subjects to regroup or integrate the letter sequences more frequently and produced similar transfer effects as in Experiments I and II.     

Implicit sequence learning in ring‐tailed lemurs (Lemur catta)

Implicit learning involves picking up information from the environment without explicit instruction or conscious awareness of the learning process. In nonhuman animals, conscious awareness is impossible to assess, so we define implicit learning as occurring when animals acquire information beyond what is required for successful task performance. While implicit learning has been documented in some nonhuman species, it has not been explored in prosimian primates. Here we ask whether ring‐tailed lemurs (Lemur catta) learn sequential information implicitly. We tested lemurs in a modified version of the serial reaction time task on a touch screen computer. Lemurs were required to respond to any picture within a 2 × 2 grid of pictures immediately after its surrounding border flickered. Over 20 training sessions, both the locations and the identities of the images remained constant and response times gradually decreased. Subsequently, the locations and/or the identities of the images were disrupted. Response times indicated that the lemurs had learned the physical location sequence required in original training but did not learn the identity of the images. Our results reveal that ring‐tailed lemurs can implicitly learn spatial sequences, and raise questions about which scenarios and evolutionary pressures give rise to perceptual versus motor‐implicit sequence learning.     

Visuospatial working memory influences the interaction between space and time

How do representations of space inform our perception of time? In language, spatial vocabulary is frequently used to describe temporal concepts, and spatial information biases temporal perception even in non-verbal tasks. In contrast, temporal information typically exerts little, if any, influence on the perception of spatial extent. Here, we used spatial and temporal reproduction tasks, both with and without verbal and spatial dual tasks, to investigate the mechanism underlying the asymmetric relation between space and time. Specifically, we tested whether the asymmetric interference between spatial and temporal stimulus attributes arises from interference in verbal or visuospatial working memory. We found that loading visuospatial working memory, but not verbal working memory, eliminated the asymmetric pattern of interference. This suggests that the interference between spatial and temporal representations arises due to processing constraints in visuospatial working memory. These findings are discussed in terms of the load theory of attention and the relative automaticity with which spatial and temporal information is processed.     

Lexical leverage: category knowledge boosts real‐time novel word recognition in 2‐year‐olds

Recent research suggests that infants tend to add words to their vocabulary that are semantically related to other known words, though it is not clear why this pattern emerges. In this paper, we explore whether infants leverage their existing vocabulary and semantic knowledge when interpreting novel label–object mappings in real time. We initially identified categorical domains for which individual 24‐month‐old infants have relatively higher and lower levels of knowledge, irrespective of overall vocabulary size. Next, we taught infants novel words in these higher and lower knowledge domains and then asked if their subsequent real‐time recognition of these items varied as a function of their category knowledge. While our participants successfully acquired the novel label–object mappings in our task, there were important differences in the way infants recognized these words in real time. Namely, infants showed more robust recognition of high (vs. low) domain knowledge words. These findings suggest that dense semantic structure facilitates early word learning and real‐time novel word recognition.     

Effects of contextual diversity on semantic decision and reading aloud: evidence from a word learning study in English as a second language / Efectos de la diversidad contextual en la decisión semántica y la lectura en voz alta: evidencia de un estudio de aprendizaje de palabras en inglés como segundo idioma

This experiment investigated contextual diversity effects on novel word learning in English as a second language (L2). A group of advanced English speakers, whose native language was Spanish, participated in the study. Participants learned the meaning of real but obscure words that were embedded in either two or 12 different sentences and learned over two days (frequency of exposure was kept constant). On day three, participants were tested using reading aloud and semantic decision tasks. The results showed that participants learned the meaning of words in both conditions fairly well as revealed by their accuracy in the semantic decision task. However, words experienced in 12 different contexts generated more accurate and faster reaction times (RTs), suggesting the acquisition of more robust semantic representations. Strikingly, reading latencies were also faster for the 12-sentence condition, which might imply that semantics has an effect on reading newly learned words in English as a second language. These results are discussed and accommodated in view of the DRC and the PDP models of single-word reading.