A diffusion model for the congruency sequence effect.

Two-choice reaction tasks for which stimuli differ on irrelevant and relevant dimensions (e.g., Simon, flanker, and Stroop tasks) show congruency effects. The diffusion model for conflict tasks (DMC) has provided a quantitative account of the mechanisms underlying decisions in such conflict tasks, but it has not been applied to the congruency sequence effect (CSE) for which the congruency on the prior trial influences performance on the current trial. The present study expands analysis of the reaction time (RT) distributions reflected by delta plots to the CSE, and then extends the DMC to simulate the results. With increasing RT: (1) the spatial Simon effect was almost unchanged following congruent trials but initially became smaller and finally reversed following incongruent trials; (2) the arrow-based Simon effects increased following both congruent and incongruent trials, but more so for the former than the latter; (3) the flanker congruency effect varied quadratically following congruent trials but increased linearly following incongruent trials. These results were modeled by the CSE-DMC, extended from the DMC with two additional assumptions: (1) feature integration influences only the controlled processes; (2) following incongruent trials, the automatic process is weakened. The results fit better with the CSE-DMC than with two variants that separately had only one of the two additional assumptions. These findings indicate that the CSEs for different conflict tasks have disparate RT distributions and that these disparities are likely due to the controlled and automatic processes being influenced differently for each trial sequence.

Word- and arrow-based Simon effects emerge for eccentrically presented location words and arrows.

Two experiments examined whether the location-based Simon effect and word- or arrow-based Simon effects, and their interaction, emerge in the same task situations by presenting location words and (left and right, Experiment 1) or single-headed arrows (left and right pointing, Experiment 2) in the left-right visual field. These tasks include two attributes of task-irrelevant location information, physical location and either location word (Experiment 1) or arrow direction (Experiment 2), when they vary jointly for a single stimulus. Moreover, the location-based Simon effect in these tasks was compared to that obtained in a pure location-based Simon task. Results showed that (1) the location-, word- and arrow-based Simon effects occurred on both mean RT and delta plots; (2) the word- and arrow-based Simon effects interacted with the location-based Simon effect on mean RT; (3) the Simon effect in the pure location-based Simon task differed little from the location-based Simon effect in the two joint Simon tasks. These results indicate that different task-irrelevant spatial attributes can influence responses in the same task, and that one of them can influence the effect of the other on responses. This latter result offers evidence that the different attributes do not provide separate sources of activation.

The location-based Simon effect: Reliability of ex-Gaussian analysis.

Task-irrelevant stimulus location can influence the response performance to task-relevant attributes, generating the location-based Simon effect. Using a Monte Carlo study and other methods, we examined whether the ex-Gaussian distribution provides a good fit to empirical reaction time (RT) distributions in the Simon task and whether reliable Simon effects occur on the ex-Gaussian parameters: (a) the mean (µ), (b) the standard deviation (σ) of the normal distribution, and (c) the tail (τ). Results showed that the ex-Gaussian function fits well to empirical RT distributions, and that these ex-Gaussian parameters are reliable between two trial blocks at the group level. At the individual level, correlation analysis showed that the Simon effect was reliable on the µ parameter but not on σ and τ. Moreover, a partial correlation analysis, with µs of the two blocks as controlling variables, showed that the Simon effect on τ was reliable. These results provide evidence that the ex-Gaussian function is a valuable tool for analyzing the Simon effect and can be considered as an alternative for analyzing RT distributions in Simon-type tasks.

Shared mechanisms underlying the location-, word- and arrow-based Simon effects.

A left or right keypress response to a relevant stimulus attribute (e.g., color) is faster when irrelevant left or right stimulus-location information corresponds with the correct response than when it does not. This phenomenon, known as the Simon effect, is obtained not only for physical locations, but also location words "left" and "right" and left- or right-pointing arrows. However, these location-, word-, and arrow-based Simon effects show different patterns in the reaction-time (RT) distributions, as evident in delta plots. In the present study, we employed procedures, analysis of survival curves and divergence point analysis, which have not previously been applied to the Simon effect, to investigate differences in time course of these various Simon effects in more detail. Also, we examined whether the diffusion model for conflict tasks (DMC), which assumes that automatic activation of task-irrelevant information occurs in a pulse-like function, can capture not only features of the RT distributions for the location-based Simon effect, to which it has been fit previously, but also features of the word- and arrow-based Simon effects, to which it has not. Results showed different survival curves and earliest, maximum, and latest divergence points for the three Simon effects, but DMC was able to capture the basic features of the RT distributions reflected by delta plot and survival curves for all effects. The results imply that the location-, word-, and arrow-based Simon effects have shared mechanisms, although they have different RT distributions.

How different direct association routes influence the indirect route in the same Simon-like task.

The location-, word-, and arrow-based Simon effects are usually attributed to the result of a direct route (the spatially corresponding stimulus-response association, activated automatically) that interferes with an indirect route (the association of task-relevant information and response, activated in accordance with the instructed stimulus-response mapping). We examined whether and how distinct direct routes (stimulus-location-response position and location word-response position or arrow direction-response position associations) affect responding on the basis of the same indirect route (a stimulus color-response association) in a Simon-like task. For this task, left-right keypresses were made to indicate the ink colors of location words or left- or right-pointing arrows, presented eccentrically in left or right locations. The location-based Simon effect occurred at the levels of mean reaction time (RT) and RT distribution in the word Simon-like task, whereas the word-based Simon effect only occurred at the level of RT distribution. In the arrow Simon-like task, the location-based Simon effect did not occur at the level of mean RT, but did at the level of RT distribution, whereas the opposite pattern occurred for the arrow-based Simon effect. These results could imply that one direct route influences the effects of the other direct route on the responses, depending on the task context.

Beyond the leftward limit of the perceptual span: Parafoveal processing to the left of fixation in Chinese reading.

During reading, Chinese readers have been found to obtain useful visual information from one character to the left to three characters to the right of fixation. The perceptual span is asymmetrical, and its leftward extent seems to be limited compared with the rightward extent. We conducted an experiment to investigate whether Chinese readers could process written information beyond the leftward extent of the perceptual span. We did this by using a variation of the gaze-contingent display change paradigm (Rayner, Cognitive Psychology, 81, 65-81, 1975) in order to manipulate the parafoveal "postview" that was available to the left of where readers were fixating. Each sentence contained an invisible boundary. Once the readers' eyes crossed the boundary, all of the characters to the left of the boundary except for one, two, or three characters directly to the left of the boundary were replaced with visually similar characters. The change lasted for only one single fixation, resulting in four different "postview" conditions including a control condition (n - 1, n - 2, n - 3, control). The results showed that, compared with the control condition, there were more regressions to the display change area immediately after readers' eyes crossed the boundary in the n - 1, n - 2, and n - 3 conditions, demonstrating that readers can acquire information from the three characters to the left of fixation at least.

The location-, word-, and arrow-based Simon effects: An ex-Gaussian analysis.

Task-irrelevant spatial information, conveyed by stimulus location, location word, or arrow direction, can influence the response to task-relevant attributes, generating the location-, word-, and arrow-based Simon effects. We examined whether different mechanisms are involved in the generation of these Simon effects by fitting a mathematical ex-Gaussian function to empirical response time (RT) distributions. Specifically, we tested whether which ex-Gaussian parameters (µ, σ, and τ) show Simon effects and whether the location-, word, and arrow-based effects are on different parameters. Results show that the location-based Simon effect occurred on mean RT and µ but not on τ, and a reverse Simon effect occurred on σ. In contrast, a positive word-based Simon effect was obtained on all these measures (including σ), and a positive arrow-based Simon effect was evident on mean RT, σ, and τ but not µ. The arrow-based Simon effect was not different from the word-based Simon effect on τ or σ but was on µ and mean RT. These distinct results on mean RT and ex-Gaussian parameters provide evidence that spatial information conveyed by the various location modes are different in the time-course of activation.

How different location modes influence responses in a Simon-like task.

Spatial information can be conveyed not only by stimulus position but by the meaning of a location word or direction of an arrow. We examined whether all the location-, arrow- and word-based Simon effects or some of them can be observed when a location word or an arrow is presented eccentrically and a left-right keypress is made to indicate its ink color. Results showed that only the location-based Simon effect was observed for location words, whereas an additional smaller arrow-based Simon effect, compared to the location-based Simon effect was observed, for arrows. These results showed spatial location, arrow direction, and location word stimulus dimensions affect response position codes in a spatial-to-verbal priority order, consistent with the possibility that they can activate mode-specific spatial representations.

Transfer of an implied incompatible spatial mapping to a Simon task.

When location words left and right are presented in left and right locations and mapped to left and right keypress responses in the Hedge and Marsh (1975) task (Arend & Wandmacher, 1987), a compatible mapping of words to responses yields a benefit for stimulus-response location correspondence (sometimes called the Simon effect), whereas an incompatible mapping yields a benefit for noncorrespondence (called the Hedge and Marsh reversal). Experiment 1 replicated the correspondence benefit and its reversal by using Chinese location words [symbol: see text] (left) and [symbol: see text] (right) in the Hedge and Marsh task. Experiments 2 and 3 examined whether the tendency to respond with the noncorresponding response when the mapping is incompatible transfers to the task version in which the mapping is compatible, and Experiment 4 examined whether transfer similarly occurs from the compatible mapping to the task version with incompatible mapping. Transfer of the incompatible relation was apparent in a lack of correspondence benefit when the mapping was changed to compatible, but transfer of the compatible relation to the incompatible mapping did not occur. The results suggest that an association between noncorresponding stimulus-response locations is acquired when the word-response mapping is incompatible, even though this relation is only implicit, regardless of whether through misapplication of a logical recoding rule or spatial representations shared by the locations and words. These associations then continue to affect processing of location when the mapping is compatible.

Perceptual grouping of objects occupied by target and flankers affects target-flanker interference.

We report four experiments that tested whether object-based attentional spreading can be modulated by the perceptual structure of objects occupied by target and flankers in a flanker task. The target and flankers were presented on a single object or three separate objects (of same or different shape), displayed at fixed, known locations. The flanker compatibility effect was larger when the target and flankers were on the same object or on three objects of the same shape than when they were on three objects of different shapes, indicating that perceptual grouping of background objects occupied by target and flankers can affect the target-flanker interference. These results imply that attention likely spreads across different objects occupied by target and flankers when these objects are separated by small gaps or have identical shapes, and attentional spreading is impeded when these objects have different shapes, suggesting that object-based attentional spreading can be modulated by the perceptual structure of objects.

Lack of visual field asymmetries for spatial cueing in reading parafoveal Chinese characters.

In two experiments, we investigated whether visual field (VF) asymmetries of spatial cueing are involved in reading parafoveal Chinese characters. These characters are different from linearly arranged alphabetic words in that they are logograms that are confined to a constant, square-shaped area and are composed of only a few radicals. We observed a cueing effect, but it did not vary with the VF in which the Chinese character was presented, regardless of whether the cue validity (the ratio of validly to invalidly cued targets) was 1:1 or 7:3. These results suggest that VF asymmetries of spatial cueing do not affect the reading of parafoveal Chinese characters, contrary to the reading of alphabetic words. The mechanisms of spatial attention in reading parafoveal English-like words and Chinese characters are discussed.

The theory-of-mind network in support of action verb comprehension: evidence from an fMRI study.

The theory-of-mind (ToM) network refers to a specific group of brain regions implicated in the thinking of people's mental states. It remains unclear how this network contributes to verb comprehension. In the present study, we compared brain activations evoked by verbs that refer to social actions, private actions, and nonhuman events. All classic regions of the ToM network, including the posterior superior temporal sulcus (pSTS) whose activation during word comprehension is typically interpreted as the processing of motion properties, showed stronger activations to social action verbs than the others. These findings indicate that the ToM network is involved in the processing of social/mental knowledge of verb meanings. Furthermore, the activation of the pSTS during word comprehension mainly reflects the processing of social/mental properties but not that of biological-motion properties.

A Stroop effect emerges in the processing of complex Chinese characters that contain a color-related radical.

Three experiments examined whether a Stroop effect emerges in the processing of complex Chinese characters that contain a color-related radical. In Experiment 1, a Stroop effect occurred when participants responded to the black or white color of the simple characters [Chinese character: see text] (black) and [Chinese character: see text] (white) by making a left or right keypress. For Experiment 2, in which the stimuli were complex characters whose meanings were unrelated to color but that contained [Chinese character: see text] or [Chinese character: see text] as a radical, a Stroop effect also occurred, although it was smaller than in Experiment 1. Furthermore, this Stroop effect as a function of radical meaning was shown again in Experiment 3 for low-frequency complex characters but not high-frequency ones. These results suggest that the semantic representations of the complex characters' color-related radicals are accessed in the context of a Stroop color word task, especially for low-frequency characters. Reduction of the Stroop effect in complex characters composed of one radical with color meaning and one without is similar to dilution of the Stroop effect that occurs when a color word is accompanied by a neutral word. Possible implications of the results for accounts of Stroop dilution are discussed.

Spatial Stroop interference occurs in the processing of radicals of ideogrammic compounds.

In this study, we investigated whether the meanings of radicals are involved in reading ideogrammic compounds in a spatial Stroop task. We found spatial Stroop effects of similar size for the simple characters [symbol: see text] ("up") and [symbol: see text] ("down") and for the complex characters [symbol: see text] ("nervous") and [symbol: see text] ("nervous"), which are ideogrammic compounds containing a radical [symbol: see text] or [symbol: see text], in Experiments 1 and 2. In Experiment 3, the spatial Stroop effects were also similar for the simple characters [symbol: see text] ("east") and [symbol: see text] ("west") and for the complex characters [symbol: see text] ("state") and [symbol: see text] ("spray"), which contain [symbol: see text] and [symbol: see text] as radicals. This outcome occurred regardless of whether the task was to identify the character (Exps. 1 and 3) or its location (Exp. 2). Thus, the spatial Stroop effect emerges in the processing of radicals just as it does for processing simple characters. This finding suggests that when reading ideogrammic compounds, (a) their radicals' meanings can be processed and (b) ideogrammic compounds have little or no influence on their radicals' semantic processing.

Determinants of breastfeeding at discharge in rural China.

This study aimed to investigate the rate of breastfeeding at discharge and associated influencing factors in rural China. A prospective cohort study of infant feeding practices was undertaken during 2010-2011 in Jiangyou city, Sichuan Province of China. Logistic regression analysis was performed to ascertain pertinent factors affecting the prevalence of any breastfeeding at discharge. The participants consisted of 695 mothers aged 18-44 years. The breastfeeding rate at discharge was 93.5% (95% CI: 91.7-95.3). Perceived paternal breastfeeding preference was positively associated with actual breastfeeding at discharge (OR=4.46, 95% CI: 2.15-9.28). Other significant determinants were 'receiving breastfeeding support' from staff during hospital stay (OR=3.41, 95% CI: 1.58-7.34) and making the decision on feeding method during pregnancy or after childbirth (OR=0.46, 95% CI: 0.22-0.93). In conclusion, provision of comprehensive breastfeeding support in hospital and education programs targeting expectant and future parents are recommended to further increase the rate of breastfeeding at discharge in rural areas of China.

Reduction of the spatial stroop effect by peripheral cueing as a function of the presence/absence of placeholders.

In a paradigm combining spatial Stroop with spatial cueing, the current study investigated the role of the presence vs. absence of placeholders on the reduction of the spatial Stroop effect by peripheral cueing. At a short cue-target interval, the modulation of peripheral cueing over the spatial Stroop effect was observed independently of the presence/absence of placeholders. At the long cue-target interval, however, this modulation over the spatial Stroop effect only occurred in the placeholders-present condition. These findings show that placeholders are modulators but not mediators of the reduction of the spatial Stroop effect by peripheral cueing, which further favor the cue-target integration account.

Asymmetry of congruency effects in spatial Stroop tasks can be eliminated.

Three experiments examined whether asymmetry in interference can be eliminated in spatial Stroop tasks. In Experiment 1, responding to arrows or location words written in Chinese and to their locations created spatial Stroop effects of similar sizes. In Experiment 2, responding to a location word embedded in an outline drawing of arrow did not yield a spatial Stroop effect, but responding to the arrow's direction did yield an effect. In Experiment 3, responding to a location word flanked by an arrow and to the arrow rather than the word produced similar sizes of spatial Stroop effects. These results show that asymmetry in spatial Stroop interference can be eliminated in some situations. Although aspects of the results are consistent with predictions of translation and dimensional overlap models, they are in closest agreement overall with an account in terms of the relative strengths of the relevant and irrelevant stimulus-response associations.

[Comparison of clinical characteristics between rifampin-dependent and rifampin- resistant patients with pulmonary tuberculosis].

OBJECTIVE: To compare the clinical characteristics of rifampin-dependent (R-dependent Mycobacterium tuberculosis) and rifampin-resistant (R-resistant Mycobacterium tuberculosis) patients with pulmonary tuberculosis. METHODS: The clinical data including the demographic data, age groups, course of disease, history of chemotherapy with anti-TB drugs, and results of drug susceptibility test were collected from 61 cases of R-dependent pulmonary tuberculosis and 148 cases of R-resistant pulmonary tuberculosis treated between October, 2008 and January, 2012. RESULTS: Most of the R-dependent and R-resistant patients were between 30 and 44 years of age. The R-dependent patients included 12 receiving the first treatment patients and 49 with previous treatments, and the R-resistant patients included 11 without and 137 with previous treatments. The multi-drug resistant rate was 80.3% in R-dependent group, as compared to 92.6% in R-resistant group. CONCLUSION: Most of the patients infected with R-dependent Mycobacterium tuberculosis are young or middle-aged, often having serious disease conditions. Detecting rifampin dependence is important for patients with initial treatment failure. Multi-drug resistance therapy guideline should be applied to patients infected with R-dependent Mycobacterium tuberculosis to improve the cure rate.

The beginning of the rpoB gene in addition to the rifampin resistance determination region might be needed for identifying rifampin/rifabutin cross-resistance in multidrug-resistant Mycobacterium tuberculosis isolates from Southern China.

We aimed to study the distribution and contribution of mutations in the rpoB whole gene in rifampin-resistant/rifabutin-resistant (RIF(r)/Rfb(r)) (or RIF/Rfb cross-resistant) clinical Mycobacterium tuberculosis isolates. One standard M. tuberculosis strain (H37Rv) and 392 other clinical M. tuberculosis isolates mainly from Guangdong Province of China whose susceptibilities to rifampin (RIF), rifabutin (Rfb), streptomycin (SM), ethambutol (EMB), and isoniazid (INH) were previously determined were subjected to DNA sequencing of their rpoB whole genes. H37Rv and the 30 drug-susceptible clinical isolates had no mutations in rpoB whole genes. In 43 rifampin-resistant/rifabutin-susceptible (RIF(r)/Rfb(s)) isolates, the most frequent mutation codons were 516 (62.80%), 526 (14.0%), and 533 (6.98%), but codon 531 had no mutation. Twenty-one of the 43 isolates (48.84%) had single mutations of H526L, H526S, D516V, D516Y, and D516F. In 319 RIF(r)/Rfb(r) isolates, the most frequent mutation codons were 531 (73.7%) and 526 (18.8%); the mutation frequency for codon 516 was 2.5%, and that for codon 533 was only 0.31%. A total of 82.8% (264/319) of them had single mutations of S531L, S531W, H526D, H526Y, H526R, Q513K, Q513P, Q510H, V176F, P206(T)R, Y314(T)C, and H323(T)Y (the superscript T indicates M. tuberculosis numbering; the remaining codons use the E. coli numbering), among which V176F, P206(T)R, Y314(T)C, and H323(T)Y were located in the beginning of rpoB, and all of them were present in 1.9% (6/319) of RIF(r)/Rfb(r) isolates. The multiple mutations in RIF(r)/Rfb(r) isolates and in RIF(r)/Rfb(s) isolates were also different from each other either in mutation positions or in types of mutation combinations. In conclusion, the mutations of rpoB in RIF-R/Rfb(s) and in RIF-R/Rfb-R isolates differ significantly from each other not only in the most frequent mutation codons (516, 531, and 533) but also in the most frequent single mutations (S531L, H526L, D516V, D516Y, and D516F), and the beginning of rpoB may confer a RIF/Rfb cross-resistance phenotype in M. tuberculosis. Molecular assays for identifying RIF/Rfb cross-resistance in M. tuberculosis might be improved in terms of accuracy by including this region, in addition to the rifampin resistance determination region.

The modulation of spatial congruency by object-based attention: analysing the "locus" of the modulation.

Earlier studies have demonstrated that spatial cueing differentially reduces stimulus-stimulus congruency (e.g., spatial Stroop) interference but not stimulus-response congruency (e.g., Simon; e.g., Lupiáñez & Funes, 2005). This spatial cueing modulation over spatial Stroop seems to be entirely attributable to object-based attention (e.g., Luo, Lupiáñez, Funes, & Fu, 2010). In the present study, two experiments were conducted to further explore whether the cueing modulation of spatial Stroop is object based and/or space based and to analyse the "locus" of this modulation. In Experiment 1, we found that the cueing modulation over spatial Stroop is entirely object based, independent of stimulus-response congruency. In Experiment 2, we observed that the modulation of object-based attention over the spatial Stroop only occurred at a short cue-target interval (i.e., stimulus onset asynchrony; SOA), whereas the stimulus-response congruency effect was not modulated either by object-based or by location-based attentional cueing. The overall pattern of results suggests that the spatial cueing modulation over spatial Stroop arises from object-based attention and occurs at the perceptual stage of processing.