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David Aagten-Murphy

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David Aagten-Murphy

Post-Doc in Cognitive Science, University of Florence

Contacts

  • Email: David.AagtenMurphy (AT) gmail.com
  • Telephone:  +39 050 3153175
Research laboratories
  • University of Sydney, Sydney, Australia
  • CNR Institute of Neuroscience, Pisa
  • Department of Psychology, University of Florence
  • Stella Maris Foundation, Pisa, Italy
  • Institute of Education, London, UK

Education

  • 2010 – 2013       Università Degli Studi di Firenze     Firenze, FI, Italia
    PhD in Psychology (Dottorato in Psicologia XXV)
    Thesis title: Efficient Encoding of Time and Number in Development and Autism 
    (Supervisors: Professor David Burr & Dr Liz Pellicano)
  • 2008 – 2009       The University Of Sydney     Darlington, NSW, Australia
    Bachelor of Science – Psychology (Hons – Class I) 
    Thesis title: Auditory Depth Perception of Motion in the Near-Field
    (Supervisor: Associate Professor David Alais)
  • 2005 – 2007      The University Of Sydney      Darlington, NSW, Australia
    Bachelor of Science (Psychology & Neuroscience)

Current research and interests

  • Numerosity perception
  • Multi-sensory perception
  • Visual integration and segmentation
  • Autism

Publications

2012

Taubert, J., Aagten-Murphy, D. & Parr, L. A. (2012). A comparative study of face processing using scrambled faces,Perception, 4 (41), 460-473. PDF

It is a widespread assumption that all primate species process faces in the same way because the species are closely related and they engage in similar social interactions. However, this approach ignores potentially interesting and informative differences that may exist between species. This paper describes a comparative study of holistic face processing. Twelve subjects (six chimpanzees Pan troglodytes and six rhesus monkeys Macaca mulatta) were trained to discriminate whole faces (faces with features in their canonical position) and feature-scrambled faces in two separate conditions. We found that both species tended to match the global configuration of features over local features, providing strong evidence of global precedence. In addition, we show that both species were better able to generalize from a learned configuration to an entirely novel configuration when they were first trained to match feature-scrambled faces compared to when they were trained with whole faces. This result implies that the subjects were able to access local information easier when facial features were presented in a scrambled configuration and is consistent with a holistic processing hypothesis. Interestingly, these data also suggest that, while holistic processing in chimpanzees is tuned to own-species faces, monkeys have a more general approach towards all faces. Thus, while these data confirm that both chimpanzees and rhesus monkeys process faces holistically, they also indicate that there are differences between the species that warrant further investigation.

Manning, C., Aagten-Murphy, D. & Pellicano, E. (2012). The development of speed discrimination abilities,Vision Res, (70), 27-33. PDF

The processing of speed is a critical part of a child's visual development, allowing children to track and interact with moving objects. Despite such importance, no study has investigated the developmental trajectory of speed discrimination abilities or precisely when these abilities become adult-like. Here, we measured speed discrimination thresholds in 5-, 7-, 9-, 11-year-olds and adults using random dot stimuli with two different reference speeds (slow: 1.5 deg/s; fast: 6 deg/s). Sensitivity for both reference speeds improved exponentially with age and, at all ages, participants were more sensitive to the faster reference speed. However, sensitivity to slow speeds followed a more protracted developmental trajectory than that for faster speeds. Furthermore, sensitivity to the faster reference speed reached adult-like levels by 11 years, whereas sensitivity to the slower reference speed was not yet adult-like by this age. Different developmental trajectories may reflect distinct systems for processing fast and slow speeds. The reasonably late development of speed processing abilities may be due to inherent limits in the integration of neuronal responses in motion-sensitive areas in early childhood.

2011

Taubert, J., Apthorp, D., Aagten-Murphy, D. & Alais, D. (2011). The role of holistic processing in face perception: evidence from the face inversion effect,Vision Res, 11 (51), 1273-1278.PDF

A large body of research supports the hypothesis that the human visual system does not process a face as a collection of separable facial features but as an integrated perceptual whole. One common assumption is that we quickly build holistic representations to extract useful second-order information provided by the variation between the faces of different individuals. An alternative account suggests holistic processing is a fast, early grouping process that first serves to distinguish faces from other competing objects. From this perspective, holistic processing is a quick initial response to the first-order information present in every face. To test this hypothesis we developed a novel paradigm for measuring the face inversion effect, a standard marker of holistic face processing, that measures the minimum exposure time required to discriminate between two stimuli. These new data demonstrate that holistic processing operates on whole upright faces, regardless of whether subjects are required to extract first- or second-level information. In light of this, we argue that holistic processing is a general mechanism that may occur at an earlier stage of face perception than individual discrimination to support the rapid detection of face stimuli in everyday visual scenes.

Conferences

  • Aagten-Murphy, D., & Burr, D.C. (2012). Brief adaptation-induced plasticity of perception of number. Perception 41 ECVP Abstract Supplement, 41, page 242. [ECVP 2012: Poster].
  • Pellicano, E., Aagten-Murphy, D., Daniel N., & Burr, D. (2012). Number sense in Autism. Perception 41 ECVP Abstract Supplement, 41, page 35-36. [ECVP 2012: Talk].
  • Tinelli, F., Anobile, G., Gori, M., Aagten-Murphy, D., Cioni, G., Burr, D., & Morrone, M.C. (2012). Perception of numerosity, time and attention in preterm children of low birth-weight. Perception 41 ECVP Abstract Supplement, 41, page 36. [ECVP 2012: Talk].
  • Castaldi, E., Aagten-Murphy, D., Tosetti, M., Burr, D., & Morrone, M.C. (2012). Number adaptation does not alter BOLD signal in V1. Perception 41 ECVP Abstract Supplement, 41, page 186. [ECVP 2012: Poster].
  • Manning, C., Aagten-Murphy, D., & Pellicano, E. (2012). The development of speed discrimination abilities. Perception 41 ECVP Abstract Supplement, 41, page 21. [ECVP 2012: Poster].
  • Aagten-Murphy, D., Cappagli, G., & Burr, D.C. (2012). Musical training generalises across modalities and reveals efficient and adaptive mechanisms for judging temporal intervals. Seeing and Percieving, 25 IMRF 2012 Abstract Supplement, page 13. [IMRF 2012: Talk - Student Award].
  • Manning, C., Aagten-Murphy, D., Charman, T., & Pellicano, E. (2012). Speed discrimination abilities in typical development and in children with autism. 12th Annual Meeting of the International Meeting for Autism Research (IMFAR), Toronto, Canada. [IMFAR 2012: Poster]
  • Aagten-Murphy, D., & Burr, D.C. (2011). Brief adaptation-induced plasticity of perception of number. Perception 40 ECVP Abstract Supplement, 40, page 21. [ECVP 2011: Talk].
  • Aagten-Murphy, D., Taubert, J., & Parr, L.A. (2010). First-order interference in a face discrimination task for nonhuman primates. Perception 39 ECVP Abstract Supplement, 39, page 92. [ECVP 2010: Poster].
  • Taubert, J., Parr, L. A., & Aagten-Murphy, D. (2010). How first-order information contributes to face discrimination in nonhuman primates. Journal of Vision, 10(7), 649. [VSS 2010: Poster].
Theses
  • Aagten-Murphy, D. Efficient Encoding of Time and Number in Development and Autism. PhD thesis, University of Florence (2013).
  • Murphy, D. Auditory Depth Perception of Motion in the Near-Field. Honours thesis, University of Sydney (2009).

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