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Bio

Bio


I am specifically interested in the development of attentional mechanisms and its intersection with the development of reading ability (and therefore reading disability). I am broadly interested in understanding the basic mechanisms that are causally related to naturally occurring conditions, like amblyopia and dyslexia, and how understanding basic mechanisms can be implemented in effective remediation. In particular, Dyslexia interests me as a model to investigate the development and the intersection of visual attentional mechanisms in the development of reading. At Stanford, my research will focus on the role of visual attention in Dyslexia.

Institute Affiliations


  • Member, Maternal & Child Health Research Institute (MCHRI)

Honors & Awards


  • Postdoctoral award, MCHRI (2021)

Stanford Advisors


Community and International Work


  • Volunteer lead

    Partnering Organization(s)

    Association for India's development

    Populations Served

    Marginalized communities in India

    Location

    International

    Ongoing Project

    Yes

    Opportunities for Student Involvement

    No

Publications

All Publications


  • Rapid online assessment of reading ability. Scientific reports Yeatman, J. D., Tang, K. A., Donnelly, P. M., Yablonski, M., Ramamurthy, M., Karipidis, I. I., Caffarra, S., Takada, M. E., Kanopka, K., Ben-Shachar, M., Domingue, B. W. 2021; 11 (1): 6396

    Abstract

    An accurate model of the factors that contribute to individual differences in reading ability depends on data collection in large, diverse and representative samples of research participants. However, that is rarely feasible due to the constraints imposed by standardized measures of reading ability which require test administration by trained clinicians or researchers. Here we explore whether a simple, two-alternative forced choice, time limited lexical decision task (LDT), self-delivered through the web-browser, can serve as an accurate and reliable measure of reading ability. We found that performance on the LDT is highly correlated with scores on standardized measures of reading ability such as the Woodcock-Johnson Letter Word Identification test (r=0.91, disattenuated r=0.94). Importantly, the LDT reading ability measure is highly reliable (r=0.97). After optimizing the list of words and pseudowords based on item response theory, we found that a short experiment with 76 trials (2-3min) provides a reliable (r=0.95) measure of reading ability. Thus, the self-administered, Rapid Online Assessment of Reading ability (ROAR) developed here overcomes the constraints of resource-intensive, in-person reading assessment, and provides an efficient and automated tool for effective online research into the mechanisms of reading (dis)ability.

    View details for DOI 10.1038/s41598-021-85907-x

    View details for PubMedID 33737729

  • The ups and downs of sensory eye balance: Monocular deprivation has a biphasic effect on interocular dominance. Vision research Ramamurthy, M. n., Blaser, E. n. 2021; 183: 53?60

    Abstract

    Classic studies of ocular dominance plasticity in early development showed that monocular deprivation suppresses the neural representation and visual function of the deprived eye. However, recent studies have shown that a short period of monocular deprivation (<3 h) in normal adult humans, shifts sensory eye dominance in favor of the deprived eye. How can these opposing effects be reconciled? Here we argue that there are two systems acting in opposition at different time scales. A fast acting, stabilizing, homeostatic system that rapidly decreases gain in the non-deprived eye or increases gain in the deprived eye, and a relatively sluggish system that shifts balance toward the non-deprived eye, in an effort to reduce input of little utility to active vision. If true, then continuous deprivation should produce a biphasic effect on interocular balance, first shifting balance away from the non-deprived eye, then towards it. Here we investigated the time course of the deprivation effect by monocularly depriving typical adults for 10 h and conducting tests of sensory eye balance at six intervening time points. Consistent with previous short-term deprivation work, we found shifts in sensory eye dominance away from the non-deprived eye up until approximately 5 h. We then observed a turning point, with balance shifting back towards the non-deprived eye, -, a biphasic effect. We argue that this turning point marks where the rapid homeostatic response saturates and is overtaken by the slower system responsible for suppressing monocular input of limited utility.

    View details for DOI 10.1016/j.visres.2021.01.010

    View details for PubMedID 33684826

  • Assessing the kaleidoscope of monocular deprivation effects JOURNAL OF VISION Ramamurthy, M., Blaser, E. 2018; 18 (13): 14

    Abstract

    Short-term monocular deprivation (?150 min) temporarily shifts sensory eye balance in favor of the deprived eye (Lunghi, Burr, & Morrone, 2011; Zhou, Clavagnier, & Hess, 2013), opposite to classic deprivation studies (Hubel & Wiesel, 1970). Various types of deprivation-light-tight, diffuser lenses, image degradation-have been tested, and it seemed that a deprivation of contrast was necessary, and sufficient, for these shifts. This could be accommodated in a feedforward model of binocular combination (Meese, Georgeson, & Baker, 2006; Sperling & Ding, 2010), in which the shift reflects a (persistent) reweighting induced by an interocular gain control mechanism tasked with maintaining binocular balance (Zhou, Clavagnier, et al., 2013). Here, we used a novel "kaleidoscopic" monocular deprivation that, although it rendered images fractionated and uninformative, preserved gross luminance, color, spatial frequency, motion, and contrast information, effectively sneaking the image degradation past early, feedforward mechanisms, targeting higher levels. Kaleidoscopic deprivation produced effects indistinguishable from traditional light-tight patching. This rules out contrast imbalance as the sole factor driving these shifts in sensory eye balance. In addition, since the suppression of the kaleidoscopic image likely requires feedback from higher-level processes capable of determining the behavioral relevance of an eye's information (Foley & Miyanshi, 1969; Jiang, Costello, & He, 2007; Kovács, Papathomas, Yang, & Fehér, 1996; Wolf & Hochstein, 2011), feedforward-only models may need to be elaborated.

    View details for DOI 10.1167/18.13.14

    View details for Web of Science ID 000454710400014

    View details for PubMedID 30572342

  • New rules for visual selection: Isolating procedural attention JOURNAL OF VISION Ramamurthy, M., Blaser, E. 2017; 17 (2): 18

    Abstract

    High performance in well-practiced, everyday tasks-driving, sports, gaming-suggests a kind of procedural attention that can allocate processing resources to behaviorally relevant information in an unsupervised manner. Here we show that training can lead to a new, automatic attentional selection rule that operates in the absence of bottom-up, salience-driven triggers and willful top-down selection. Taking advantage of the fact that attention modulates motion aftereffects, observers were presented with a bivectorial display with overlapping, iso-salient red and green dot fields moving to the right and left, respectively, while distracted by a demanding auditory two-back memory task. Before training, since the motion vectors canceled each other out, no net motion aftereffect (MAE) was found. However, after 3 days (0.5 hr/day) of training, during which observers practiced selectively attending to the red, rightward field, a significant net MAE was observed-even when top-down selection was again distracted. Further experiments showed that these results were not due to perceptual learning, and that the new rule targeted the motion, and not the color of the target dot field, and global, not local, motion signals; thus, the new rule was: "select the rightward field." This study builds on recent work on selection history-driven and reward-driven biases, but uses a novel paradigm where the allocation of visual processing resources are measured passively, offline, and when the observer's ability to execute top-down selection is defeated.

    View details for DOI 10.1167/17.2.18

    View details for Web of Science ID 000397220000018

    View details for PubMedID 28245497

  • Color shifts at different viewing eccentricities on flat-panel rear projection displays in steps of perceptibility threshold units JOURNAL OF MODERN OPTICS Ramamurthy, M., Hovis, J., Zsivanov, D., Lakshminarayanan, V. 2013; 60 (14): 1151-1158

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