Winnie Wai Lan Chan

Developmental dyscalculia and low numeracy in Chinese children

Children struggle with mathematics for different reasons. Developmental dyscalculia and low numeracy - two kinds of mathematical difficulties - may have their roots, respectively, in poor understanding of exact non-symbolic numerosities and of symbolic numerals. This study was the first to explore whether Chinese children, despite cultural and linguistic factors supporting their mathematical learning, also showed such mathematical difficulties and whether such difficulties have measurable impact on childrens early school mathematical performance. First-graders, classified as dyscalculia, low numeracy, or normal achievement, were compared for their performance in various school mathematical tasks requiring a grasp of non-symbolic numerosities (i.e., non-symbolic tasks) or an understanding of symbolic numerals (i.e., symbolic tasks). Children with dyscalculia showed poorer performance than their peers in non-symbolic tasks but not symbolic ones, whereas those with low numeracy showed poorer performance in symbolic tasks but not non-symbolic ones. As hypothesized, these findings suggested that dyscalculia and low numeracy were distinct deficits and caused by deficits in non-symbolic and symbolic processing, respectively. These findings went beyond prior research that only documented generally low mathematical achievements for these two groups of children. Moreover, these deficits appeared to be persistent and could not be remedied simply through day-to-day school mathematical learning. The present findings highlighted the importance of tailoring early learning support for children with these distinct deficits, and pointed to future directions for the screening of such mathematical difficulties among Chinese children.

Processing of configural and componential information in face-selective cortical areas

We investigated how face-selective cortical areas process configural and componential face information and how race of faces may influence these processes. Participants saw blurred (preserving configural information), scrambled (preserving componential information), and whole faces during fMRI scan, and performed a post-scan face recognition task using blurred or scrambled faces. The fusiform face area (FFA) showed stronger activation to blurred than to scrambled faces, and equivalent responses to blurred and whole faces. The occipital face area (OFA) showed stronger activation to whole than to blurred faces, which elicited similar responses to scrambled faces. Therefore, the FFA may be more tuned to process configural than componential information, whereas the OFA similarly participates in perception of both. Differences in recognizing own- and other-race blurred faces were correlated with differences in FFA activation to those faces, suggesting that configural processing within the FFA may underlie the other-race effect in face recognition.

Exploring the developmental changes in automatic two-digit number processing

Even when two-digit numbers are irrelevant to the task at hand, adults process them. Do children process numbers automatically, and if so, what kind of information is activated? In a novel dot-number Stroop task, children (Grades 1-5) and adults were shown two different two-digit numbers made up of dots. Participants were asked to select the number that contained the larger dots. If numbers are processed automatically, reaction time for dot size judgment should be affected by numerical characteristics. The results suggest that, like adults, children process two-digit numbers automatically. Based on the current findings, we propose a developmental trend for automatic two-digit number processing that goes from decomposed sequential (activation of decade digit followed by that of unit digit) to decomposed parallel processing (simultaneous activation of decade and unit digits).

The underlying number-space mapping among kindergarteners and its relation with early numerical abilities.

People map numbers onto space. The well-replicated SNARC (spatial-numerical association of response codes) effect indicates that people have a left-sided bias when responding to small numbers and a right-sided bias when responding to large numbers. This study examined whether such spatial codes were tagged to the ordinal or magnitude information of numbers among kindergarteners and whether it was related to early numerical abilities. Based on the traditional magnitude judgment task, we developed two variant tasks-namely the month judgment task and dot judgment task-to elicit ordinal and magnitude processing of numbers, respectively. Results showed that kindergarteners oriented small numbers toward the left side and large numbers toward the right side when processing the ordinal information of numbers in the month judgment task but not when processing the magnitude information in the number judgment task and dot judgment task, suggesting that the left-to-right spatial bias was probably tagged to the ordinal but not magnitude property of numbers. Moreover, the strength of the SNARC effect was not related to early numerical abilities. These findings have important implications for the early spatial representation of numbers and its role in numerical performance among kindergarteners.

Face transformation in recollection and familiarity

Three classical face recognition tasks (viewpoint, inversion, spatial frequency) were assessed using the remember/know procedure to examine how different transformations of the face influence recollection and familiarity in recognition memory. In the viewpoint task, participants studied front-view faces and were tested with front, three-quarter and profile views. Participants gave significantly higher remember responses to front view faces than three-quarter views, with profile views lower still. However, no difference in know responses among the three viewpoints was found. A viewpoint effect was observed in remember responses We then conducted the inversion task, in which participants studied both upright and inverted faces, and then were tested on each type. An inversion effect was observed with remember responses but not know responses. There was no difference in know responses between upright and inverted faces if participants studied upright faces. However, higher know responses were found for inverted faces than upright faces when participants studied inverted faces. These results indicate that feelings of familiarity can only be transferred from upright faces to inverted faces but not the other way round. The poor observed performance with inverted faces is indicative of a disruption of holistic processing. Therefore, in the final experiment we separated different spatial frequencies from faces to examine recollection and familiarity with low- and high-spatial frequency faces. Participants studied intact faces and were tested with intact, HSF and LSF faces. High numbers of remember responses were observed for intact faces only. No differences were found for either HSF and LSF. Based on the results of these three studies, recollection appears to be comparatively more sensitive to face transformation than familiarity. However, the extent to which configural processing is the basis for recollection is not yet clear. Meeting abstract presented at VSS 2015.

Can Non-Interactive Language Input Benefit Young Second-Language Learners?.

To fully acquire a language, especially its phonology, children need linguistic input from native speakers early on. When interaction with native speakers is not always possible - e.g. for children learning a second language that is not the societal language - audios are commonly used as an affordable substitute. But does such non-interactive input work? Two experiments evaluated the usefulness of audio storybooks in acquiring a more native-like second-language accent. Young children, first- and second-graders in Hong Kong whose native language was Cantonese Chinese, were given take-home listening assignments in a second language, either English or Putonghua Chinese. Accent ratings of the childrens story reading revealed measurable benefits of non-interactive input from native speakers. The benefits were far more robust for Putonghua than English. Implications for second-language accent acquisition are discussed.