Clyde Street

Learning, Teaching, Performing

Seeing and Enhancing?

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I spend a lot of time thinking about observation.

This week news of a paper written by Christopher Chambers, Christopher Allen, Leah Maizey, and Mark Williams has added to my contemplation.

The paper published in Cortex is titled ‘Is delayed foveal feedback critical for extra-foveal perception?‘. The abstract is:

Recent neuroimaging evidence suggests that visual inputs arising beyond the fovea can be ‘fed back’ to foveal visual cortex to construct a new retinotopic representation. However, whether these representations are critical for extra-foveal perception remains unclear. Using transcranial magnetic stimulation we found that relatively late (350–400 msec) disruption of foveal retinotopic cortex impaired perceptual discrimination of objects in the periphery. These results are consistent with the hypothesis that feedback to the foveal retinotopic cortex is crucial for extra-foveal perception, and provide additional evidence for ‘constructive’ feedback in human vision.

In an ABC Science News post about the paper, Anna Salleh points out that this research encourages conjecture about the peripheral vision system :

  • Feeding back information to the foveal region to give extra information to the central vision.
  • Using the extra processing power of the foveal region as a kind of “scratch pad” to improve itself.

Mark Williams points out in his conversation with Anna that “Peripheral vision is best at picking up things in the dark and detecting movement. Our central vision, on the other hand, is best for focusing and detecting colour”.

Chris Chambers (the first author of the paper) has posted about the paper too. In his post he writes:

Peripheral vision is useful. Whether you’re an astronomer who practices ‘averted vision’, or a footballer monitoring for defenders, or even just attending covertly to a weirdo on the Tube – in each situation, looking directly at what you’re attending to may not be the best course of action.

Evidence is now mounting that when we attend to objects in the periphery, critical information about them is transmitted, or ‘fed back’, to an unexpected part of the brain: a region that neuroscientists have traditionally believed represents only the ‘fovea’, our central visual field.
Exactly why this feedback of information occurs isn’t yet clear. But one possibility is that the visual system harnesses the resolving power of the foveal cortex to enhance our peripheral vision, much like a small-town police force sending important CCTV footage to the ‘big city’ for analysis.
Chris provides a detailed account of his work with Mark Williams and has a copy of the paper available for download. I think his post as a briefing is an outstanding example of sharing insight into a research question and its investigation.
The research used two experiments. There were eighteen neurologically healthy, right-handed volunteers in Experiment 1 (nine females; mean age = 26.2 years). All participants had normal or corrected- to-normal vision and were initially screened for medical contraindications to TMS and MRI. There were ten volunteers were in Experiment 2 (six females; mean age = 23.9 years), one of whom had participated in Experiment 1.
The paper prompted me to think about individual variation in peripheral vision and how the construction of learning environments might stimulate this extra-foveal perception. I wondered too about how we are able to discuss what we have seen when each of us may have different peripheral feedback potential.
Photo Credits

Author: Keith Lyons

Clyde Street has been my WordPress blog since June 2008. I write about learning, teaching and performing.

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