Subword activation in reading Japanese single Kanji character words.

Kanji are categorized into four types based on the combination of "subword validity" (when the right phonemic radical represents the same On reading as the whole Kanji character) and "radical-neighbor consistency" (when the whole Kanji character represents the same On reading with all its neighbor characters). The study demonstrated that both subword validity and radical-neighbor consistency affect naming latencies and error rates for relatively high-frequency Kanji character words. Moreover, both analytic and holistic decoding processes, which correspond to subword and whole-character activation, are used in the naming of Japanese single Kanji character words. Accounts of the findings by dual-route and connectionist models are discussed.     

Rhythmic information in working memory: effects of concurrent articulation on reproduction of rhythms

The study addressed a previously neglected issue in the concept of working memory, namely whether or not rhythmical information is coded and maintained in a phonological loop. Thirty subjects engaged in a task which required them to reproduce the temporal sequence of rhythm. The results showed that the reproduction of rhythm was dramatically reduced by a concurrent articulation, and that the deterioration of rhythm reproduction was larger than that obtained with a concurrent spatial task which would not diminish the activity of the phonological loop directly. An articulatory component of the working memory apparently plays an important role in memorizing rhythms. Furthermore, the sparse-dense rhythm (a pattern which started with sparse temporal structure and ended with a dense one) allowed better memorization than a dense-sparse pattern. The sources of the sparse-dense superiority effect are discussed in terms of the working memory for rhythmic information.     

The homophone effect in semantic access tasks using kanji words: its relation to the articulatory suppression effect

The present study examined whether articulatory suppression influences homophone effects in semantic access tasks using Japanese kanji words. In Experiment 1, participants were required to decide whether visually presented word pairs were synonyms. This experiment replicated the homophone effect observed in previous research that showed more false positive errors in response to nonsynonym homophone pairs than to controls. The present study found that this homophone effect was also obtained under an articulatory suppression condition. In Experiment 2, participants performed a semantic decision task, in which they had to judge whether a visually presented target word was an exemplar of a definition that was shown immediately before presentation of the target word. The homophone effect observed in previous studies was replicated--that is, longer response times and more false positive errors were associated with homophones of correct exemplars than with nonhomophone control words. This homophone effect was also obtained under an articulatory suppression conditions. These results suggest that the phonological processing that produces the homophone effects in semantic access tasks using Japanese kanji words does not include articulatory mechanisms.     

Phase-dependent synaptic changes in the hippocampal CA1 field underlying extinction processes in freely moving rats

Recent studies focus on the functional significance of a novel form of synaptic plasticity, low-frequency stimulation (LFS)-induced synaptic potentiation in the hippocampal CA1 area. In the present study, we elucidated dynamic changes in synaptic function in the CA1 field during extinction processes associated with context-dependent fear memory in freely moving rats, with a focus on LFS-induced synaptic plasticity. Synaptic transmission in the CA1 field was transiently depressed during each extinction trial, but synaptic efficacy was gradually enhanced by repeated extinction trials, accompanied by decreases in freezing. On the day following the extinction training, synaptic transmission did not show further changes during extinction retrieval, suggesting that the hippocampal synaptic transmission that underlies extinction processes changes in a phase-dependent manner. The synaptic potentiation produced by extinction training was mimicked by synaptic changes induced by LFS (0.5 Hz) in the group that previously received footshock conditioning. Furthermore, the expression of freezing during re-exposure to footshock box was significantly reduced in the LFS application group in a manner similar to the extinction group. These results suggest that LFS-induced synaptic plasticity may be associated with the extinction processes that underlie context-dependent fear memory. This hypothesis was supported by the fact that synaptic potentiation induced by extinction training did not occur in a juvenile stress model that exhibited extinction deficits. Given the similarity between these electrophysiological and behavioral data, LFS-induced synaptic plasticity may be related to extinction learning, with some aspects of neuronal oscillations, during the acquisition and/or consolidation of extinction memory.     

"Blue and seven phenomena" among Japanese students

To investigate color and number preferences in Japan, 586 university undergraduates (239 men and 347 women; M age = 20.9 yr.) were asked to name a color (Question 1), to name their preferred color (Question 2), and to name their preferred number between zero and nine (Question 3). The results showed that Japanese students chose blue (33.5%) or red (26.0%) when asked to name a color but that red was not chosen as frequently as blue as a preferred color (red: 11.1%, blue: 37.1%). Sex differences were found on both Questions 1 and 2 by chi-squared test. Black was chosen more by men, while pink was selected more by women. 22.5% subjects also selected the number seven, supporting Simon's observation of the "blue-seven phenomenon." The reasons given for the choice showed that seven was "a lucky number" and "represented happiness" among Japanese students. Four colors (blue, red, white, and black) accounted for 76.8% and 65.1% of responses to Questions 1 and 2, respectively, and odd numbers 68.4% for Question 3.     

Effects of response-stimulus interval manipulation and articulatory suppression on task switching

We conducted three experiments using a list paradigm to examine how articulatory suppression and response-stimulus interval (RSI) manipulation affected task switching. Experiments 1 and 2 tested task-switching performance under a short and long RSI and three concurrent task conditions (control, articulatory suppression, and tapping) without external task cues. The results indicated that alternation had a greater effect under articulatory suppression than under the control and tapping conditions, and that articulatory suppression costs were unrelated to the RSI. In Experiment 3, an external task cue was provided with each stimulus, and the negative effect of articulatory suppression on alternation cost was eliminated. These results indicated that articulatory suppression effects did not differ between conditions of short and long RSI and that the availability of verbal representations of task information was independent of RSI length. This paper discussed the possible roles played by the phonological loop in task-switching paradigms.     

Electron spin resonance of hydrogenated amorphous silicon-carbon alloy films prepared by magnetron sputtering

Abstract

New electron spin resonance (ESR) lines with g¹ = 2·0017 and g₂ and g₃ = 2·0006 have been found in the ESR spectra of as-deposited a-Si_1–x C_x:H films prepared by magnetron sputtering of silicon in the gas mixtures of methane and argon. Similarities between the observed spectra and those for the E′ centre in glassy SiO₂ are discussed.     

Cognitive load on working memory both encourages and discourages reasoning bias regarding the mental states of others

Theory of mind (ToM) refers to the ability to reason about the mental states of others. An increasing number of studies have revealed that working memory (WM) plays an important role in ToM. The present study applied WM loads to adults during a ToM task in order to investigate the impact on mental‐state reasoning performance. The task required participants to estimate the probabilities of several possible behaviours for a protagonist following the presentation of a ToM story. Participants were also required to maintain a meaningless two‐ (light WM load) or seven‐letter English alphabet string (heavy WM load) during story comprehension and mental‐state reasoning. The results show that the combination of light WM load applied during story comprehension with heavy WM load during mental‐state reasoning results in an overestimation of the probability that the protagonist's behaviour will accord with a participant's knowledge. Conversely, a heavy WM load applied during story comprehension, regardless of the type of WM load during mental‐state reasoning, did not result in this probability estimation bias. We discuss these findings from the perspective of a WM representation account.     

Breaking a habit: A further role of the phonological loop in action control

Recent research has suggested that keeping track of a task goal in rapid task switching may depend on the phonological loop component of working memory. In this study, we investigated whether the phonological loop plays a similar role when a single switch extending over several trials is required after many trials on which one has performed a competing task. Participants were shown pairs of digits varying in numerical and physical size, and they were required to decide which digit was numerically or physically larger. An experimental cycle consisted of four blocks of 24 trials. In Experiment 1, participants in the task change groups performed the numerical-size judgment task during the first three blocks, and then changed to the physical-size judgment task in the fourth. Participants in the continuation groups performed only the physical-size judgment task throughout all four blocks. We found negative effects of articulatory suppression on the fourth block, but only in the task change groups. Experiment 2 was a replication, with the modification that both groups received identical instructions and practice. Experiment 3 was a further replication using numerical-size judgment as the target task. The results showed a pattern similar to that from Experiment 1, with negative effects of articulatory suppression found only in the task change group. The congruity of numerical and physical size had a reliable effect on performance in all three experiments, but unlike the task change, it did not reliably interact with articulatory suppression. The results suggest that in addition to its well-established role in rapid task switching, the phonological loop also contributes to active goal maintenance in longer-term action control.