Professor Fiona Macpherson has been awarded a Royal Society of Edinburgh grant (International Joint Projects - Stream 1) for a project on New Foundations of the Structure of Perception with collaborator Professor EJ Green from Johns Hopkins University.

This project will enable visits and exchanges between researchers at the Centre for the Study of Perceptual Experience, University of Glasgow and researchers in The Foundations of Mind, at Johns Hopkins University, from August 20025 – 2007.

The philosophy of perception is in flux. The standard model of the structure or underlying organizational principles of perception has many parts. It asserts that perception (what we see and hear, touch and taste, among other senses) and cognition (what we think about what we see and hear, etc.) are independent faculties of the mind. It asserts that we experience constant sizes, shapes, colours and locations, despite persistent changes in sensory signals as we move around the world. It asserts that types of sensory features such as colours, sounds, and pains have internal structures. For example, pains hurt, colours have opponencies (blue is opposite yellow), sounds have timbre, loudness and pitch. The model also asserts that perception itself occurs consciously but can also happen in unconscious processes. This list is not exhaustive. However, it is representative of a suite of principles that have been influential over the last half century and that collectively describe a default or standard view about the underlying structure of perception.

Work done in recent years at the Centre for the Study of Perceptual Experience (CSPE) at the University of Glasgow and at the Foundations of Mind Group (FMG) at John Hopkins University has challenged every part of this foundation. We will continue to challenge it. However, we also want to collectively build a new model. The purpose of this initial partnership is to give us the opportunity to build a professional team between these research centres over the next two years. Over this period, we will hold one workshop at each institution, with all team members present. We will collaborate remotely on new and ongoing research projects. We expect 1-2 outputs from each team member—including some jointly written—to emerge through this collaboration. In addition, over the two years we will develop a large-scale grant application involving both teams, whose aim is to shape the new theoretical foundations of the structure of perception (e.g. AHRC Standard Grant)

The structure or organizational principles of perception are a collection of rules that govern our perceptual lives. Some of the rules are external to perception in the sense that they pertain to how perception interacts with other facets of our minds like cognition or action. Some of the rules are internal to perception, such as perception having intentionality (being directed toward the world). Some are internal to a particular sense modality like vision, audition, or proprioception. Some are internal to specific perceptible properties like colour or pain. Collectively, these rules define an overall structure of perception and of perceptual experience (or consciousness). The nature of these rules is varied, and this is best appreciated through some examples drawn from our research.

For decades it has been commonly held that perception and cognition are functionally independent modules or units, and in particular that perception is encapsulated from cognition. The idea is not that the two do not communicate. On the contrary, perception can send messages to cognition (we can think about what we hear) and cognition can send messages to perception (we can intentionally turn our eyes to look at what we hear). The idea is instead that once perceptual organs are directed to the right place, it is up to perception and perception alone to determine what is perceived. Thus, once you turn your eyes to look at what you hear, your eyes alone will determine what you see by reference to what is in the environment. You may hope to see one thing instead of another, but your eyes will process the available visual information independently of this desire. This is what it means to say that perception is encapsulated from cognition.

In recent years a flurry of research has challenged and defended the encapsulation of perception from cognition, and members of the CSPE and FMG have been leading this research. For example, Macpherson (2012, 2017), Director of CSPE, forcefully argues that the encapsulation needs to be reconsidered, for there is evidence that beliefs affect the colours we experience in the world. By contrast, Firestone, co-Director of FMG, argues that the arguments against encapsulation are problematic (Firestone and Scholl 2016). One upshot of this and other research is that the boundary between perception and cognition is far less understood than we thought, and likely very messy (Lyons 2015, Green 2020, Gross forthcoming, and various additional publications from CSPE and FMG).

A second example pertains to perceptual constancies, the tendency of perceptual systems, especially vision, to generate stable perceptual experiences across changes in incoming perceptual signals. For example, the light outside changes dramatically throughout the day, yet the colours of things are perceptibly stable or at least do not shift nearly as much as the light does. The perspectival shapes and sizes of objects change as objects rotate and move toward or further from the perceiver. For example, things that are further away occupy less of the visual field than things close up. Yet we generally experience rotating objects as having a stable shape, and receding objects as having a stable size. Perceptually, constancies are an organizational ruleset governing perceptions. The phenomenon has been understood in terms of the inverse optics approach to perception. The incoming sensory signal conflates information about object colour and lighting conditions, about intrinsic shape and orientation, and about intrinsic size and distance from perceiver. According to the inverse optics approach, perceptual constancy is the computational problem of disambiguating the sensory signal to track the distal, stable colours, shapes and sizes of things in our environment.

New Foundations of the Structure of Perception

In recent years our understanding of perceptual constancy has evolved considerably, in part from work from members of CSPE and FMG. Brown (2014), Deputy Director of CSPE, argues that colour vision tracks lighting conditions as well as object colour, but that it doesn’t do either terribly well (Brown 2021). Green (2019), co-Director of FMG, argues that shape constancy isn’t restricted to static shape but extends to intrinsic structure. For example, we can see that someone’s body shape is constant as they walk, even though their ‘static shape’ changes significantly with the movement of their limbs at their joints. Both sets of research argue that the inverse optics approach is at best a rough initial component of the structure of constancy systems. Perceptual constancies thus remain a central part of the structure of perception but we have moved some distance from the standard view. We could provide equally compelling and important descriptions about how our research has pushed our understanding of the structure of perception in various other ways, including regarding the relationship between conscious and unconscious perception (Phillips 2021), hearing silence (Goh, Phillips and Firestone 2023), the structure of pain (Bain 2014, 2017), perceptual experiences of impossibilities (Won, Gross and Firestone 2021, Macpherson 2021), the link between perception and imagination (Brown 2018, Macpherson 2018, Phillips 2014), the format of perceptual representations (Gross forthcoming, Lyons 2022), ethical perception (Cowan 2015), the nature of perceptual imagination (Blomkvist 2022, Macpherson 2018), among other examples. Overall, a new standard model of the structure of perception is needed.

Our aim in this partnership is to bring these researchers together to work toward a new standard model. We do not all agree on how to resolve each puzzle, and, as mentioned above, in some cases have defended opposing views. However, we do all agree that many facets of the standard model of the structure of perception are in disrepair. A credible new model will emerge over the next decade, and we aim to be at the forefront of this emergence. This requires an initial period in which to develop a steady working relationship with one another, and a subsequent longer period in which to work out a new model. This application connects to both. This funding would permit the CSPE team to visit Baltimore for a workshop in year one with two goals. First, we would present our recent research to one another, which in philosophy involves extended discussions on each of our research topics. Second, we would organize working sessions aimed at the initial development stage of a large-scale grant project proposal that would cover the subsequent longer period needed for the broader project. This funding would also trigger in kind funding from Johns Hopkins University, which would permit the FMG group to visit Glasgow for a trip the following year. That trip would also involve a workshop on our current research and follow-up meetings on the large-scale grant project. In between the meetings, we will collaborate remotely on various points of overlap in our work. At the end of the two years, we anticipate having a solid professional team that can deliver on the broader aims in the years that follow.

Intended Impact: The research will interest the philosophical community and is expected to impact psychology and neuroscience, as new models of perception from our work will be tested by empirical sciences. FMG’s links to empirical scientists will boost the influence of the CSPE team’s work in that domain. The CSPE has successfully run a perceptual illusion stall at public events, including European Researchers Night and Glasgow Science Festival. This partnership will provide access to FMG’s expertise in areas like “hearing silence” and “structural constancy,” guiding the creation of new public exhibition displays. FMG does not currently have a public engagement exhibition, and we will assist them in developing one for U.S. events. Both research groups have significant media impact experience and will leverage their respective networks, providing a broader reach for both. Senior members with media expertise will mentor junior members, helping them develop this skillset further.

First published: 11 March 2025

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