A standard model of contrast detection: psychophysical probes and an international testbed

A primary goal in understanding human vision has been to characterise the details of the initial stage of spatial filtering of the retinal image and to understand the processes of feature integration and segmentation across the image. By learning about the very limits of vision (e.g. the lowest contrast that an image or its part can be just about seen) we learn about the fundamental constraints and strategies of the human signal detection system. Following this approach, I developed the noisy energy model of contrast detection (e.g. Meese & Summers, 2012), including a thorough characterisation of contrast sensitivity across the retinae (Baldwin et al, 2012). Analytic stimuli (e.g. Meese, 2010) were used to test and develop the model, addressing several gnarly issues in the field including internal noise, the level of intrinsic uncertainty, and the forms of contrast transduction and signal integration.

The main project aim is to extend the model to test it against the modelfest data set (from the NASA website). The new version will extend the model to 2D by including multiple spatial filters and investigate how filter outputs should be combined. A critical factor to the development will be determining the boundary conditions for signal integration, to be tested with appropriate experimentation. A secondary aim is to run previously successful models of the ModelFest results on several of my own challenging (and published) data sets. A third aim is to develop new stimuli that will allow further tests and comparisons between the competing models. A final aim is to test the fully specified 2D model on external noise stimuli for which there is strong theoretical motivation.

The project involves computational modelling and psychophyical experimentation. Candidates will need strong programing and quantitative skills and a basic background in visual perception and/or experimental psychology.

Some relevant references

• Modelfest details (including stimuli) can be found here http://vision.arc.nasa.gov/modelfest/

• Baldwin, Meese & Baker (2012) The attenuation surface for contrast sensitivity has the form of a witch’s hat within the central visual field. Journal of Vision, 12(11):23, 1-17.

• Meese (2010) Spatially extensive summation of contrast-energy is revealed by contrast detection of micro-pattern textures. Journal of Vision, 10(8):14, 1-21.

• Meese & Summers (2012) Theory and data for area summation of contrast with and without uncertainty: Evidence for a noisy energy model. Journal of Vision, 12(11):9, 1-28.

• Watson & Ahumada (2005) A standard model of foveal detection of spatial contrast. Journal of Vision, 5, 717-740.

Candidates should have been awarded, or expect to achieve, EITHER:

a] a First or Upper Second Class award in their Undergraduate Degree (Bachelors or UG Masters) from a UK institution, in a subject judged by Aston to be relevant to the proposed research.

OR

b] a Merit (or above)* in a Postgraduate Masters degree in a relevant subject AND an Undergraduate Degree (Bachelors or UG Masters), both from UK institutions.

*where appropriate.

Qualifications from overseas institutions will be also considered but performance must be equivalent to that described above, and the University reserves the right to ascertain this equivalence according to its own criteria.

Financial Support

This project covers the Home tuition fees. Candidates who do not have Home status will be responsible for the difference in tuition fees. Currently, the difference between ‘Home’ and the ‘Overseas’ tuition fees is £17,712 for 2026/7.  

Overseas Applicants

Overseas applicants may apply for this studentship but will need to pay the difference between the ‘Home’ and the ‘Overseas’ tuition fees. Currently, the difference between ‘Home’ and the ‘Overseas’ tuition fees is £17,712 for 2026/7. As part of the application, you will be required to confirm that you will provide this additional funding. Please indicate this on the application form in the funding section.
 

Apply through our PhD application form.

When applying:

• For University College, please select Health and Life Sciences
• For Degree Programme, please select Research Health Sciences (including Optometry, Pharmacy, and Psychology Research Areas) and your preferred entry date.

Apply now

If you require further information about the application process please contact the Postgraduate Admissions team at pgr_admissions@aston.ac.uk

Supervisor: Prof Tim Meese

Associate Supervisor: Prof Andrew Schofield

Contact information

For formal enquiries about this project contact Prof Tim Meese at t.s.meese@aston.ac.uk.

PhD programmes are for those who are seeking to develop greater in-depth knowledge in a specific area. Completing this level of study is about making an original contribution to knowledge, making new discoveries and developing lifelong skills. 

Studying a PhD is great route into academia and industries that are centred on research and innovation. Areas with a demand for very high level and specialised research skills often demand PhDs.

In addition to this specialist knowledge, PhD education will help you to develop a set of valuable transferrable skills. The very nature of studying an intensive research degree will enable you to become a team player, develop problem-solving skills, analytical thinking, and advanced presentation and communication skills.