IS DIGIT SUPERIORITY INDISPENSABLE WITH REGARD TO SHORT TERM MEMORY SPAN?

It is known that digits have a positive effect on the performance of short term memory (STM) span and it is called the digit superiority effect. This study aims to examine the effect of familiar stimuli (digits, colors, digit names, color names, and words) on STM span. In order to measure STM capacity, a memory span task was used including the digit, word, and color span lists. 91 participants (44 female, 47 male) aged between 18-27 (M = 21,43, SD = 1.50) participated in the study that consisted of three different experiments. Results of Experiment 1 revealed that there was a significant difference between the digit name and word with regard to span size and total span. In Experiment 2 and 3, the main effect of familiar stimulus type on total span and span size was significant, and also the difference between all types of stimuli was significant (Experiment II, digit name>word=color name; Experiment III, digit>digit name>color name>color). The common result obtained from all experiments is that digits are superior with regard to STM span than other familiar stimuli types such as words, color names, colors. This study confirmed that digit superiority effect is indispensable on verbal and visual STM span. Keywords Digit superiority, short term memory, memory span

Lateralization of Color Discrimination Performance and Lexical Effects in Patients With Chronic Schizophrenia

Introduction: Patients with schizophrenia experience various visual disturbances. However, information regarding color perception in these patients is rare. In this study, we used a lateralized color search task to investigate whether difference in color name affects color recognition in patients with schizophrenia.Methods: In a color search task, we controlled the position of the target that emerged from the left visual field (LVF) or right visual field (RVF) as well as the color category. In this task, both the target and the distractors had the same or different color name (e.g., blue or green).Results: Patients with schizophrenia showed faster performance in the color search task with different color names for target-distractors when the target emerged from the LVF than when it emerged from the RVF. However, the same laterality was not observed in healthy controls. This finding indicates that semantic processing for color name differences influenced visual discrimination performance in patients with schizophrenia more profoundly in the LVF than in the RVF.Conclusion: This lateralized performance could imply the failure of the left hemisphere language processing dominance in schizophrenia. A search paradigm combining target position and category may indicate that automatic language processing depends on imbalanced hemispheric function in schizophrenia.

Response competition better explains Stroop interference than does response exclusion

Researchers debate whether Stroop interference from an incongruent word in color-naming response time is caused by response competition or by response exclusion. According to the former account, the interference reflects competition in lexical response selection during color name planning, whereas according to the latter, the interference reflects the removal of a motor program for the incongruent word from an articulatory buffer after planning. Here, numerical predictions about the magnitude of Stroop interference as a function of stimulus onset asynchrony were derived from these accounts. These predictions were then tested on representative data in the literature. Measures of goodness-of-fit showed that the numerical predictions of a response competition account are closer to the empirical data than those of the response exclusion account. These results indicate that response competition provides a better explanation of interference in naming than does response exclusion.

Richer color vocabulary is associated with better color memory but not color perception

The potential interaction between color naming and psychophysical color recognition has been historically debated. To study this interaction, here we utilized two approaches based on individual differences in color naming and variation of color name density along the color wheel. We tested a pool of Persian speaking subjects with a simple color matching task under two conditions: perceptual and memory-based matching. We also asked subjects to freely name 100 evenly sampled hues along the color wheel. We found that, individuals who possess more names to describe the color wheel have a strong edge in color memorization over those with fewer names. Nevertheless, having more or fewer color names was not related to the subjects’ performance in perceptual color matching. We also calculated the density of color names along the color wheel and observed that parts of the color wheel with higher density of color names are held in memory more accurately. However, similar to the case of individual differences, the density of color names along the wheel did not show any correlation with perceptual color matching performance. Our results demonstrate a strong link between color naming and color memorization both across different individuals and different parts of the color wheel. These results also show that low-level perceptual color matching is not related to color naming, suggesting that the variation in color naming—among the individuals and across the color wheel—is neither the cause nor the effect of variation in low-level color perception.

Rainbows Revisited: Modeling Effective Colormap Design for Graphical Inference

Color mapping is a foundational technique for visualizing scalar data. Prior literature offers guidelines for effective colormap design, such as emphasizing luminance variation while limiting changes in hue. However, empirical studies of color are largely focused on perceptual tasks. This narrow focus inhibits our understanding of how generalizable these guidelines are, particularly to tasks like visual inference that require synthesis and judgement across multiple percepts. Furthermore, the emphasis on traditional ramp designs (e.g., sequential or diverging) may sideline other key metrics or design strategies. We study how a cognitive metric---color name variation---impacts people's ability to make model-based judgments. In two graphical inference experiments, participants saw a series of color-coded scalar fields sampled from different models and assessed the relationships between these models. Contrary to conventional guidelines, participants were more accurate when viewing colormaps that cross a variety of uniquely nameable colors. We modeled participants' performance using this metric and found that it provides a better fit to the experimental data than do existing design principles. Our findings indicate cognitive advantages for colorful maps like rainbow, which exhibit high color categorization, despite their traditionally undesirable perceptual properties. We also found no evidence that color categorization would lead observers to infer false data features. Our results provide empirically grounded metrics for predicting a colormap's performance and suggest alternative guidelines for designing new quantitative colormaps to support inference. The data and materials for this paper are available at: https://osf.io/tck2r/

SSR Markers Based Genetic Diversity in Nepalese Maize Landraces

Knowledge on genetic diversity is necessary for developing new varieties and managing diversity for future use. Five SSR markers were used to develop the DNA finger prints and to assess the diversity of 23 Nepalese maize landraces. Five locus-based DNA finger prints have distinguished majority of the landraces. The average number of alleles was 2 per locus. Umc1333 marker had shown the highest gene diversity, heterozygosity and polymorphism information content (PIC). At landrace level, the highest gene diversity, heterozygosity and PIC values were found in Seto Local and Seti Makai-3. 23 maize landraces formed four clusters and these clusters were related with seed color. Name of landraces also reflected genetic similarity. Genetically similar landraces can be pooled for conservation and creating dynamic diversity rich population. Distantly related landraces (Bhirkaule, Local Seto Makai, Seto Makai-1, Makai Makai-1761) can be used in breeding program. Detection of low genetic diversity might be due to bottleneck effects during the collection of these landraces from farmers. Therefore, collection strategy needs to be revised for capturing maximum diversity. SAARC J. Agri., 18(1): 23-37 (2020)