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William Guild Building, Room S7
University of Aberdeen
Kings College
Old Aberdeen
AB24 3FX
The United Kingdom


A crucial question in vision science is how do we recognize objects? It seems trivial, easy, and self-evident, but taking a cursory look at today's artificial intelligence research (or at face detection software in cameras) is enough to suggest how incredibly complex the process is. At our lab, we have been working on uncovering the mechanisms underlying object recognition, using visual crowding as a tool. Currently, we are working on determining the neural processes underlying attention, object recognition and visual short term memory (VSTM) using a combination of psychophysics and EEG.

Object recognition

Object recognition takes place in two steps. First, the features (orientation, color, etc) of an object are detected independently. Then these features are put together to form the representation of that object. Crowding is a breakdown of the second step. When a target object is flanked closely by other objects, the features of the target and the flankersget mixed up leading to a jumbled percept. This is crowding. It offers a direct window into how feature integration occurs, and hence serves as a handy tool in investigating object recognition.

Crowding is illustrated below. Fixate (keep your eyes focused) on the black square in the center. If you try to read the central letter of the triplet on the right, you will find it very hard. The same letter at the same distance on the left is extremely easy to identify. It is the presence of the the flanking letters on the right that makes the target letter unidentifiable.

Crowding demo


Visual attention directs the limited resources of the visual system to the currently relevant input. We are interested in how attention is deployed in space in order to select objects. Currently, We are applying a variety of techniques including Steady State Visual Evoked Potentials, Multivariate Classifiers and Representational Similarity Analysis to EEG data obtained in attentional tasks to determine the shifts in spatial attention as a function of time. Similar techniques are also being applied to determine how the brain represents various features of objects, such as location and motion.

Current Research

  • Neural oscillations in attention, awareness and VSTM
  • Neural basis of crowding
  • Subitization
  • Time perception


Current Members

  • Rama's Pic

    Rama Chakravarthi


  • Rama Chakravarthi

    Lecturer and PI

  • Danai's Pic

    Danai Papadaki

    Doctoral student

  • Danai Papadaki

    Doctoral student

  • Crystal's Pic

    Crystal Silver

    Doctoral student

  • Crystal Silver

    Doctoral student

  • Justin's Pic

    Justin Claydon

    Doctoral student

  • Justin Claydon

    Doctoral student

  • Amanda's Pic

    Andy Nordqvist

    Doctoral student

  • Andy Nordqvist

    Doctoral student

Current Undergraduate Members

  • Eleanor Paterson
  • Elyshia Mistry
  • Imke Eickholt

Former Postgraduate Members

  • Josephine's Pic

    Josephine Reuther

    Post-Doctoral Fellow

  • Josephine Reuther


  • Leili's Pic

    Leili Soo

    Doctoral student

  • Leili Soo

    Doctoral student

  • Plamen's Pic

    Plamen Antonov

    Doctoral student

  • Plamen Antonov

    Doctoral student

  • Oana's Pic

    Oana Iosif

    Doctoral student

  • Oana Iosif

    Doctoral student

  • Nico's pic

    Nicholas Jeerakun


  • Nicholas Jeerakun


  • Kyle's Pic

    Kyle Ferris


  • Kyle Ferris


  • Nick's Pic

    Nicholas Hall


  • Nicholas Hall


Former Undergraduate Members

  • Sid's Pic

    Sid Henriksen

    Honours student

  • Sindre Henriksen

    Honours student

  • Diana's Pic

    Diana-Maria Marosi

    Honours student

  • Diana-Maria Marosi

    Honours student

  • Robert's Pic

    Robert Ainsley

    Summer intern

  • Robert Ainsley

    Summer intern

    Robert's summer internship was supported by the Developing Scientisits fund, during the summer of 2014. He worked on whether visual crowding could be alleviated by priming.

    Robert is a tennis enthusiast and runs his own tennis training service. He recently graduated from the University of Aberdeen.

  • Ben's Pic

    Ben Lonnqvist

    Undergraduate student

  • Ben Lonnqvist

    Undergraduate (Economics)

  • Jirko's Pic

    Jirko Rubruck

    Undergraduate student

  • Jirko Rubruck

    Undergraduate student

  • Maira's Pic

    Maira Riga

    Undergraduate student

  • Maira Riga

    Undergraduate student


  1. Chakravarthi, R., Papadaki, D. and Krajnik, J. (2022). Visual field asymmetries in numerosity processing, Attention, Perception and Psychophysics. 84 (8): 2607-2622 abstract pdf doi Covered in Nature Reviews Psychology Highlight
  2. Reuther, J., Chakravarthi, R., Martinovic, J. (2022). Masking, crowding and grouping: Connecting low and mid-level vision, Journal of Vision. 22 (2): 7 abstract pdf doi
  3. Lee, R. J., Reuther, J., Chakravarthi, R., Martinovic, J. (2021). Emergence of crowding: the role of contrast and orientation salience, Journal of Vision. abstract pdf doi
  4. § Chakravarthi, R., Rubruck, J., Kipling, N., and Clarke, A. D. F. (2021). Characterising the in-out asymmetry in visual crowding, Journal of Vision. 21 (11): 10 abstract pdf doi
  5. Silver, C. A., Tatler, B., Chakravarthi, R. , and Timmermans, B. (2021). Social Agency as a Continuum, Psychonomic Bulletin and Review, 28: 434 - 453. abstract pdf doi
  6. Poncet, M. and Chakravarthi, R. (2021). Subitizing object parts reveals a second stage of individuation, Psychonomic Bulletin and Review, 28: 476 - 486. abstract pdf SI doi
  7. Poncet, M., Fabre-Thorpe, M. and Chakravarthi, R. (2020). A simple rule to describe interactions between visual categories, European Journal of Neuroscience, 52: 4639 - 4666. abstract pdf SI doi
  8. Lonnqvist, B., Clarke, A., and Chakravarthi, R. (2020). Crowding in humans is unlike that in convolutional neural networks, Neural Networks, 126: 262 - 274. abstract pdf doi arXiv
  9. Antonov, P. A., Chakravarthi, R. , and Andersen, S. K. (2020). Too little, too late, and in the wrong place: Alpha band activity does not reflect an active mechanism of selective attention, Neuroimage, 219: 117006. abstract pdf doi
  10. Reuther, J. and Chakravarthi, R. (2020). Response selection modulates crowding: a cautionary tale for invoking top-down explanations, Attention, Perception and Psychophysics, 82: 1763 - 1778. abstract pdf doi
  11. Reuther, J., Chakravarthi, R., and Hunt, A. R. (2020). The eye that binds: Feature integration is not disrupted by saccadic eye movements, Attention, Perception and Psychophysics, 82: 533 - 549. abstract pdf doi
  12. Chakravarthi, R. and Bertamini, M. (2020). Clustering leads to underestimation of numerosity, but crowding is not the cause, Cognition, 104195. abstract pdf SI doi
  13. Chakravarthi, R. and Herbert, A. (2019). Two’s company, three’s a crowd: Individuation is necessary for object recognition, Cognition, 184: 69 - 82. abstract pdf doi
  14. Soo, L., Chakravarthi, R., and Andersen, S. K. (2018). Critical resolution: a superior measure of crowding, Vision Research, 153: 13 - 23. abstract pdf doi
  15. § Reuther, J. and Chakravarthi, R. (2017). Does self-prioritization affect perceptual processes? Visual Cognition, 1 - 18. abstract pdf doi
  16. Jennings, B. J., Tsattalios, K., Chakravarthi, R., and Martinovic, J. (2016). Combining S-cone and luminance signals adversely affects discrimination of objects within backgrounds, Scientific Reports, 6 (20504): 1-10. abstract pdf doi
  17. Costa, S. L., Gonçalves, O. F., DeLuca, J. Chiaravalloti, N., Chakravarthi, R., and Almeida, J. (2015). The temporal dynamics of visual processing in Multiple Sclerosis, Applied Neuropsychology: Adult, 23 (2): 133 - 140. abstract pdf doi
  18. Rosen, S., Chakravarthi, R., and Pelli, D. G. (2014). The Bouma law of crowding, revised: Critical spacing is equal across parts, not objects, Journal of Vision, 14 (6): 10, 1-15. abstract pdf doi Covered in a blog.
  19. Chakravarthi, R., Carlson, T. A., Chaffin, J., Turret, J., and VanRullen, R. (2014). The temporal evolution of coarse location coding of objects: Evidence for feedback. Journal of Cognitive Neuroscience, 26 (10): 2370 - 2384. abstract pdf doi
  20. Reuther, J. and Chakravarthi, R. (2014). Categorical membership modulates crowding: evidence from characters, Journal of Vision, 14 (6): 5, 1-13. abstract pdf doi
  21. Van Vugt, M. K., Chakravarthi, R., and Lachaux, J. P. (2014). For whom the bell tolls: periodic reactivation of sensory cortex in the gamma band as a substrate of visual working memory maintenance, Frontiers in Human Neuroscience, 8: 696. abstract pdf doi
  22. Chakravarthi, R. and VanRullen, R. (2012). Conscious updating is a rhythmic process, Proceedings of the National Academy of Sciences, 109 (26): 10599-10604. abstract pdf doi
  23. Freeman, J.,Chakravarthi, R., and Pelli, D. G. (2012). Substitution and pooling in crowding, Attention, Perception, & Psychophysics, 72 (4): 379 - 396 abstract pdf doi
  24. Chakravarthi, R. and Pelli, D. G. (2011). The same binding in contour integration and crowding, Journal of Vision, 11 (8): 10, 1-12. abstract pdf doi
  25. Chakravarthi, R. and VanRullen, R. (2011). Bullet trains and steam engines: Exogenous attention zips but endogenous attention chugs along, Journal of Vision, 11 (4):12, 1-12. abstract pdf doi
  26. Chakravarthi, R. and Cavanagh, P. (2009). Recovery of a crowded object by masking the distracters: Determining the locus of feature integration, Journal of Vision, 9 (10):4, 1-9. abstract pdf doi
  27. Chakravarthi, R. and Cavanagh, P. (2009). Bilateral field advantage in visual crowding, Vision Research, 49 (13): 1638 – 1646. abstract pdf doi
  28. Vickery, T. J., Shim, W. M., Chakravarthi, R., Jiang, Y. V., and Luedeman, R. (2009). Supercrowding: Weakly masking a target expands the range of crowding, Journal of Vision, 9 (2):12, 1-15. abstract pdf doi
  29. Chakravarthi, R. and Cavanagh, P. (2007). Temporal properties of the polarity advantage effect in crowding, Journal of Vision, 7 (11): 1 – 12. abstract pdf doi
  30. Ramakrishna, C. (2002). Real latencies and facilitation, Consciousness and Cognition, 11(2): 300 – 303. pdf doi

§ Preregistered/Presubmitted Study

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Rama's CV

You can download a pdf of my CV here.

Education and Employment

2012 – Present: Lecturer, School of Psychology
University of Aberdeen, Scotland UK
2009 – 2012: Post Doctoral Fellow; Advisor: Dr. Rufin VanRullen
Centre de Recherche Cerveau et Cognition CNRS, Toulouse, France,
2007 – 2009: Post Doctoral Fellow in Psychology and Neural Science; Advisor: Prof. Denis Pelli
New York University, New York NY
2002 – 2007: PhD in Psychology: Cognition, Brain and Behavior; Advisor: Prof. Patrick Cavanagh
Harvard University, Cambridge MA
1999 – 2001: M.S. in Consciousness Studies; Advisor: Dr Shantanu Nagarkatti
Birla Institute of Technology and Science, Pilani, India
1993 – 1999: M.B., B.S. (Bachelor of Medicine, Bachelor of Surgery)
Manipal Academy of Higher Education, Manipal, India

Grants and Funding

2019 – 2020: Experiencing myself through you: Self-agency in social interactions, Carnegie Research Incentive Grant awarded to Bert Timmermans and me, £9,914
2019 – 2021: Investigating the microstructure of human visual fields and generating low-vision applications, BBSRC International Partnering award granted to Dr Jasna Martinovic, Dr Daniel Coates (Houston), Dr Josephine Reuther (post-doc) and me, £10,000
2018 – 2021: Neural mechanisms of long-range spatial vision: an investigation of perceptive, integrative and association fields across the lifespan, BBSRC grant awarded to Dr Jasna Martinovic (PI) and me (co-PI), £344,000
2006 – 2007: Graduate Society Dissertation Completion Fellowship, Harvard University, $18,000
2007: Stimson travel grant for presenting at VSS conference, 2007, $500
2006: McMasters travel grant for presenting at VSS conference, 2006, $500
2005: Graduate Society Fellowship Summer Award, Harvard University, $3,000
2004: Mind, Brain and Behavior Graduate Student Award, Harvard University, $5,000
2003 – 2004: Harvard University Graduate Summer Awards, $3,000/year
2002 – 2004: Harvard University GSAS Merit Fellowship, $70,000
2000 – 2001: Sir Ratan Tata Trust Scholarship for the M.S. Program, INR 15,000

Teaching and Research supervision


Level 1:
  1. Introductory Psychology II: Evolutionary Psychology module
  2. Introduction to Biological Sciences: Consciousness module
Level 2:
  1. Advanced Psychology A: Theory and Concepts: Perception
Level 3:
  1. Perception small group tutorials
  2. Methodology B: Semester long research projects (5-7 students)
Level 4:
  1. Senior honours (research-based) thesis (4-7 students each year)
  2. Sixth Century Course on Consciousness (Levels 3 and 4)
  3. Cognitive Neuroscience (Levels 3 and 4)
Masters: Introduction to Bayesian Statistics

Research Supervision

  1. Josephine Reuther (2013-2017)
  2. Leili Soo (2014-2018)
  3. Plamen Antonov (2016-2020)
  4. Oana Iosif (2016-2020)
  5. Crystal Silver (2019-present)
  6. Danai Papadaki (2019-present)
  7. Alex Donald (2019-present)
  8. Justin Claydon (2021-present)
  9. Andy Nordqvist (2022-present)
  1. Samuel Pitt (2013-2014)
  2. Nicholas Hall (2014-2015)
  3. Nicholas Jeerakun (2017-2018)
  4. Kyle Ferris (2017-2018)
  5. Danai Papadaki (2018-2019)
  6. Mentored 3-month internships at CerCo, CNRS, France (2010-2011):
  • Julie Chaffin
  • Marion Baziard
  • Alexy Assaf

Admin Responsibilities

  • Levels 3 and 4 Cognitive Neuroscience Course-coordinator
  • Director of Communications Team
  • Equality and Diversity Committee
  • Personal tutor (non-academic mentorship) for 20-25 students per year
  • Organising Perception and Attention group meetings