Do we compute the exact number of digits in the string when comparing different-length numbers?

Recent studies have shown that, when comparing multidigit numbers that differ in length (e.g., 2384-107), a decision is made considering length but also other attributes like the value of the initial digits (i.e., left-most digit/length congruity effect: faster responses to 2384-107 than to 2675-398). A non-solved issue is whether participants choose the number with more digits by exactly computing the number of digits in the string (e.g., 3 vs. 4) or whether they simply choose the perceptually larger item. In our first study participants were presented with pairs of different length numbers (3 vs. 4-digits) and were requested to decide which multidigit starts with a larger digit. Results showed more difficulties when the smaller digit was in the 4-digit length number, suggesting that length was automatically processed even although it was irrelevant for the task. In a second study, we presented participants with pairs of 3- and 4-digit-length numbers but obscured the processing of perceptual length by including a letter at the end of the 3-digit-length numbers (e.g., 8567-342M). Additionally, we manipulated the left-most-digit/length congruity effect and presented one string in each pair in a larger font than the other. Then we requested participants to do a physical size decision task. Together with an influence of the leftmost digit in the string, no effects of digit-length were observed, thus suggesting that the exact number of digits in the string is not processed automatically. It seems participants rely on perceptual information when comparing multidigit numbers that differ in length.Universidad de Málaga. Campus de Excelencia Internacional Andalucía Tech

Individual differences in arithmetic fluency

Este estudio contrasta la hipótesis de que las dificultades que tienen algunos sujetos en el dominio de las tablas de multiplicar se deban a su incapacidad para afrontar la interferencia. Los resultados no muestran diferencias en medidas de interferencia en un tarea de recuerdo serial entre sujetos con alta y baja habilidad en la resolución de multiplicaciones. Sin embargo, se encuentran diferencias asociadas a su dominio de las representaciones numéricas.Universidad de Málaga. Campus de Excelencia Internacional Andalucía Tech. Ministerio de Economía y Competitividad. Proyecto PSI-2012-38423

Struggling with single-digit multiplications: testing several hypotheses

Between 5-10% of children suffer big difficulties in learning single-digit multiplications (Geary, 2011). In accordance with previous studies, difficulties in learning multiplications would be related with interference-control problems. The more similar the multiplications are (e.g., 4x6=24; 4x7=28), the greater is the interference that occurs when remembering them. People who have interference-control problems, would not be able to adequately retrieve the solutions (e.g., De Visscher et al., 2014). Furthermore, evidences suggest that inhibition would be a key cognitive mechanism underlying numerical development (Nath & Szücs, 2016). Another point of view defends that difficulties with basic numerical representations, or their access from symbolic formats (e.g., Arabic, verbal), would be the cause of the multiplication learning difficulties. The footprint in the memory of multiplication problems would be weakened because of an imprecise representation of the numbers and the result which compose them (e.g., Buttwerworth, 2005). This study explored whether the differences in multiplication fluency in adults are due to numerical or non-numerical abilities. High Fluency (N=17; Age=18-32) & Low Fluency (N=17; Age=18-37) groups were created according to their performance in a multiplication fluency test (High= Fluency > P85, Low=Fluency < P15). We used two tasks to assess symbolic and non-symbolic numerical representations, and two memory tasks to assess proactive and retroactive interference. We assessed inhibitory control using the Attentional Network Task, and the interaction between numerical representations and inhibition using a numerical Stroop task. Results showed differences in numerical representation tasks between groups but not in interference-control measures. A reduced numerical Stroop effect in the Low Fluency group was also found. Taking together, we conclude that deficits in the numerical domain are in the basis of single-digit multiplication problems.Universidad de Málaga. Campus de Excelencia Internacional Andalucía Tech

Length is not all that matters: testing the role of number identity and the ratio of fillers in comparisons of multi-digits with different digit length

Research in multi-digit number comparison usually considers stimuli with the same number of digits (e.g., 3452 vs. 7831). Surprisingly, there is almost no research on the comparison of numbers that differ in length (e.g., 995 vs. 1000), which demands a focus on the number of digits in each multi-digit, despite the fact that the role of number length has been explicitly acknowledged in componential models of multi-digit processing. Our study explores whether the comparison of pairs of natural numbers that differ in length is affected by the identity of the leftmost digit of each multi-digit, and asks what is the effect of having variable proportions of trials with pairs of numbers of the same-length in the task. Across three studies participants compared numbers in blocks with different proportions of same-length multi-digit pairs (Experiment 1 and 2: 25% vs. 50% vs. 75%; Experiment 3: 0% vs. 50%). Stimuli in the different-length condition were length-digit congruent (the number with more digits starting with a larger digit: 2384 vs. 107) or length-digit incongruent (the number with more digits starting with a smaller number: 2675 vs. 398). Response times were shorter in length-digit congruent pairs than in the incongruent pairs. Unexpectedly, this effect was only slightly modulated by the proportion of same-/different-length multi-digit pairs in the experimental set. Despite its perceptual saliency, length is not the only information considered when comparing different-length numbers. The leftmost-digit is also taken into account, with variable relevance here, depending on the characteristics of the stimuli set.IGC was funded by a Ph.D. scholarship from the Universidad de Málaga. Open Access funding provided thanks to the Universidad de Málaga-CBUA (CRUE-CSIC) agreement with Springer Nature. Funding for open access charge: Universidad de Málaga / CBU

Automatic processing of number identity and place-value in multi-digit numbers

The Arabic numerical system employs two dimensions to create multi-digit numbers: digits symbols and place-value. The present research explores in two numerical Stroop experiments to which extent number identity and number place-value processing is automatic in four-digit numbers. Whereas the automatic coding of place-value has been stated previously (see Kallai & Tzelgov, 2012), this has been studied in isolation using similar numbers (e.g., 0400-0040). Experiment 1 explored the access to numbers identity. Fifty-five volunteers were presented with pairs of four digit numbers that differed in one number (e.g., 0200-0400). They had to decide which number string was presented in bigger font size. Congruity between the physical size and the numerical value, distance between the numbers, and position of the discrepant numbers within the string, were manipulated. Results revealed congruity effects that were modulated by distance and position. Experiment 2 (N=90) jointly manipulated size congruity at the place-value (PV) and at the number identity (NI) dimensions (e.g., congruent NI & PV: 0100-5000; congruent NI & incongruent PV: 1000-0500; incongruent NI & congruent PV: 0500-1000; incongruent NI & incongruent PV: 5000-0100). Data analyses indicated an interaction between place-value and identity showing the automatic and simultaneous processing of both dimensions in four-digit numbers.Universidad de Málaga. Campus de Excelencia Internacional Andalucía Tech

Writing 1-to-3 digit numerals to dictation in Spanish: predictors and error analysis.

Mastering number transcoding demands from children the acquisition of the complexities of the Arabic place-value system and the specific rules of multi-digit numbers of their language. The present research explores the writing to dictation of 1-to-3-digit numerals in an initial sample of Spanish 1st (N = 208) and 2nd grade school children (N = 96). Language rules for multidigit numbers in Spanish are similar to those in other languages (e.g., Italian) with some variations: there are irregularities (e.g., inversion) between 11-15, but a regular pattern after this that involve both multiplicative and additive rules (432: cuatrocientos treinta y dos, literally: fourhundreds thirty and two”). Results indicated that 2nd grade children made anecdotical errors (< 2%), showing mostly digit substitution (lexical) errors (e.g., 167 instead of 567). First graders showed a more diverse pattern of errors (19%) with digit substitutions, syntactic errors and mixed errors. Qualitative analysis showed similar error rates for irregular and regular multidigits suggesting a non-syntactical treatment of these numbers. Within syntactic errors, we claim that transposition (107 instead of 170) and structural errors (10070 instead of 170) have different sources and involve different compensation mechanisms. Finally, in a subset of the data we also explored the role of non-symbolic comparison, number to mental line position and completion of numerical sequences in predicting number writing. Whereas completing Arabic numerical sequences arose as significant predictor, no role for variables related to the analogical representation of numbers was found. This seems to support asemantic models of transcoding.Universidad de Málaga. Campus de Excelencia Internacional Andalucía Tec

Treatment with tocilizumab or corticosteroids for COVID-19 patients with hyperinflammatory state: a multicentre cohort study (SAM-COVID-19)

Objectives: The objective of this study was to estimate the association between tocilizumab or corticosteroids and the risk of intubation or death in patients with coronavirus disease 19 (COVID-19) with a hyperinflammatory state according to clinical and laboratory parameters. Methods: A cohort study was performed in 60 Spanish hospitals including 778 patients with COVID-19 and clinical and laboratory data indicative of a hyperinflammatory state. Treatment was mainly with tocilizumab, an intermediate-high dose of corticosteroids (IHDC), a pulse dose of corticosteroids (PDC), combination therapy, or no treatment. Primary outcome was intubation or death; follow-up was 21 days. Propensity score-adjusted estimations using Cox regression (logistic regression if needed) were calculated. Propensity scores were used as confounders, matching variables and for the inverse probability of treatment weights (IPTWs). Results: In all, 88, 117, 78 and 151 patients treated with tocilizumab, IHDC, PDC, and combination therapy, respectively, were compared with 344 untreated patients. The primary endpoint occurred in 10 (11.4%), 27 (23.1%), 12 (15.4%), 40 (25.6%) and 69 (21.1%), respectively. The IPTW-based hazard ratios (odds ratio for combination therapy) for the primary endpoint were 0.32 (95%CI 0.22-0.47; p < 0.001) for tocilizumab, 0.82 (0.71-1.30; p 0.82) for IHDC, 0.61 (0.43-0.86; p 0.006) for PDC, and 1.17 (0.86-1.58; p 0.30) for combination therapy. Other applications of the propensity score provided similar results, but were not significant for PDC. Tocilizumab was also associated with lower hazard of death alone in IPTW analysis (0.07; 0.02-0.17; p < 0.001). Conclusions: Tocilizumab might be useful in COVID-19 patients with a hyperinflammatory state and should be prioritized for randomized trials in this situatio

A922 Sequential measurement of 1 hour creatinine clearance (1-CRCL) in critically ill patients at risk of acute kidney injury (AKI)

Meeting abstrac

Time to Switch to Second-line Antiretroviral Therapy in Children With Human Immunodeficiency Virus in Europe and Thailand.

Background: Data on durability of first-line antiretroviral therapy (ART) in children with human immunodeficiency virus (HIV) are limited. We assessed time to switch to second-line therapy in 16 European countries and Thailand. Methods: Children aged <18 years initiating combination ART (≥2 nucleoside reverse transcriptase inhibitors [NRTIs] plus nonnucleoside reverse transcriptase inhibitor [NNRTI] or boosted protease inhibitor [PI]) were included. Switch to second-line was defined as (i) change across drug class (PI to NNRTI or vice versa) or within PI class plus change of ≥1 NRTI; (ii) change from single to dual PI; or (iii) addition of a new drug class. Cumulative incidence of switch was calculated with death and loss to follow-up as competing risks. Results: Of 3668 children included, median age at ART initiation was 6.1 (interquartile range (IQR), 1.7-10.5) years. Initial regimens were 32% PI based, 34% nevirapine (NVP) based, and 33% efavirenz based. Median duration of follow-up was 5.4 (IQR, 2.9-8.3) years. Cumulative incidence of switch at 5 years was 21% (95% confidence interval, 20%-23%), with significant regional variations. Median time to switch was 30 (IQR, 16-58) months; two-thirds of switches were related to treatment failure. In multivariable analysis, older age, severe immunosuppression and higher viral load (VL) at ART start, and NVP-based initial regimens were associated with increased risk of switch. Conclusions: One in 5 children switched to a second-line regimen by 5 years of ART, with two-thirds failure related. Advanced HIV, older age, and NVP-based regimens were associated with increased risk of switch

Psicología educativa : revista de los psicólogos de la educación

Resumen basado en el de la publicaciónTítulo, resumen y palabras clave en español e inglésSe explora el efecto de dos métodos de enseñanza de la multiplicación simple en alumnos de primaria con diferentes niveles de habilidades matemáticas. Un método se basa en el enfoque convencional para el aprendizaje de las multiplicaciones que enfatiza la memorización de todas ellas, mientras que el otro se basa en principios psicológicos y combina: la memorización multiplicaciones auxiliadas con claves de color y una tabla portátil con las multiplicaciones con el uso de reglas de un solo paso (M&R: método de memorización y reglas). Participaron 160 niños y niñas de segundo de primaria, durante 6 meses. Se reveló que los niños con habilidades matemáticas bajas en el grupo convencional obtuvieron puntuaciones significativamente mejores que sus pares en el grupo M&R, mientras que se observó una ventaja significativa en el grupo M&R para aquellos niños con altas habilidades matemáticas.ES