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Reaching Across the Aisle to Find the Algorithms of Vision

Scientists have reason to believe that either type of process may be at play in the brain.

Credit: Ryan Garcia

Much of the foundational work on the visual system approached it in a very simple way: Show an animal an image, measure how its neurons respond, show another and repeat. The assumption — stated or not — was that visual processing could be understood as a rote input-output transformation. Scientists studied cells as though they respond based simply on the visual features present in the image; these responses could then be used to discriminate between different images.

While this basic understanding of the visual system has been fruitful in many ways, it has always left some researchers doubtful. These researchers believe that the anatomy and dynamics of the visual system suggest it is not simply responding in a 'bottom-up' way. Rather, it may be generating some of its responses based on a model of how the world works. This debate between a 'discriminative' versus a 'generative' approach to vision has gone on for decades. Though both models aim to explain visual processing, the two approaches stem from different philosophical and mathematical traditions. The result is that different researchers use only their preferred method rather than working together, creating a sharper distinction between these two approaches than the brain's behavior may warrant.

In recent years, progress in both computer vision and computational neuroscience has shown the limits of this dichotomy and encouraged more expansive modeling of visual processing. But doing so requires that representatives of both sides come together to sort out what they each believe, where they agree, and where their predictions diverge. This is just what happened in September at the virtual Cognitive Computational Neuroscience (CCN) conference during the kickoff event for a 'generative adversarial collaboration' (GAC). A GAC is a process developed by CCN in 2020 to make scientific disagreements explicit and productive. Researchers submit a proposal for a controversial topic to CCN, and a handful of proposals are selected for GAC events at the conference. The following year, GAC organizers submit a position paper laying out plans for progress on their topic area and present that progress at that year's conference.

From Simons Foundation Global Brain
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