Perceptual Learning beyond Philosophy of Mind

The concluding chapter argues that perceptual learning has relevance for philosophy far beyond philosophy of mind—in epistemology, philosophy of science, and social philosophy, among other domains. The goal of this chapter is to extend one major focus of the book, which is to identify the scope of perceptual learning. Chapters 3 through 7 argued that perceptual learning occurs in all sorts of domains in the philosophy of mind, including natural kind recognition, sensory substitution, multisensory perception, speech perception, and color perception. This chapter extends that scope beyond philosophy of mind and offers some initial sketches of ways in which we can apply knowledge of perceptual learning to those domains.

“Chunking” the World through Multisensory Perception

This chapter argues that multisensory perceptions are learned, not the result of an automatic feature binding mechanism. For example, suppose you are at a live jazz show. The drummer begins a solo. You see the cymbal jolt and hear the clang. But you are also aware that the jolt and the clang are part of the same event. Psychologists have assumed that multisensory perceptions like this one are the result of an automatic feature binding mechanism. This chapter argues instead that when you experience the jolt and the clang as part of the same event, it is the result of a perceptual learning process. The jolt and the clang are best understood as a single learned perceptual unit, not as automatically bound. This chapter details the perceptual learning process of “unitization,” whereby we come to “chunk” the world into multisensory units, and argues that unitization best explains multisensory perception.

Learned Attention and the Contents of Perception

This chapter argues that when we learn to recognize natural kinds, such as pine trees, this should be understood not in terms of kind properties coming to be represented in our perception, but simply in terms of a shift in our attention, which causes us to represent new low-level properties, such as colors, shapes, and textures. Susanna Siegel has argued that kinds, such as pine trees, can look phenomenally different to someone once that person becomes disposed to recognize them, and that the best explanation for this is that kind properties, such as being a pine tree, can become represented in perception. The chapter details an alternative explanation for the different look of the pine tree: a shift in one’s attentional pattern onto other low-level properties. Philosophers have alluded to this alternative before, but the chapter provides a comprehensive account of the view, drawing on the science of perceptual learning.

Learning to Differentiate Objects

This chapter explains memory color as an enhancement of perceptual learning, which enables us to better differentiate objects from their backgrounds. In cases of memory color, faded types of objects with which we associate a prototypical color are sometimes perceived as closer to that color than they actually are. For instance, discolored hearts sometimes appear redder to us than they actually are, and discolored bananas yellower. The goal of this chapter is to understand memory color in terms of perceptual learning. The chapter argues that memory color enhances perceptual learning by enabling us to better differentiate objects from their backgrounds. This account of cases of memory color parts ways with an influential philosophical interpretation of them: that they should be understood as cases of cognitive penetration. It also parts ways with the standard interpretation of memory color cases in psychology: that they should be understood as cases of color constancy.

How to Understand Perceptual Learning

This introductory chapter explains perceptual learning as long-term changes in perception that are the result of practice or experience. It distinguishes perceptual learning from other nearby concepts, including perceptual development and cognitive penetration. It then delineates different kinds of perceptual learning. For instance, some kinds of perceptual learning involve changes in how one attends, while other cases involve a learned ability to differentiate two properties, or to perceive two properties as unified. The chapter uses this taxonomy to distinguish different cases of perceptual learning in the philosophical literature, including by contemporary philosophers such as Susanna Siegel, Christopher Peacocke, and Charles Siewert. Finally, it outlines the function of perceptual learning. Perceptual learning serves to offload onto our quick perceptual systems what would be a slower and more cognitively taxing task were it to be done in a controlled, deliberate manner. The upshot is that this frees up cognitive resources for other tasks.

Learning to Differentiate Properties

This chapter details the role perceptual learning plays in speech perception and argues that the evidence does not show that meanings come to be represented in our perception upon learning a new language. Specifically, it outlines the role of the perceptual learning mechanism of differentiation in speech perception. Through differentiation, we come to parse features of a language, including phonemes that we had not previously differentiated. The chapter critically evaluates Casey O’Callaghan’s and Berit Brogaards’s arguments for and against the view that meanings come to be represented in our perception upon learning a new language. It argues that the evidence from perceptual learning does not support the conclusion that meanings come to be represented in our perception.

Learned Attention II

This chapter explores the relationship between sensory substitution devices and the training of attention. Sensory substitution devices, typically used by the blind, deliver information about the environment by converting the information normally received through one sense (e.g., vision) into information for another sense (e.g., audition or touch). When a user integrates a sensory substitution device into her life, the integration process involves perceptual learning. This chapter explores two questions. First, in what ways can sensory substitution illuminate how the training of attention works more generally? Second, how does knowledge of the way attention is trained in perceptual learning help us to better understand sensory substitution? The chapter draws on findings in these areas to answer a philosophical question: Should the post-perceptual learning experience be classified in the substituted modality (e.g., as vision), in the substituting modality (e.g., as auditory or tactile), or in a new sense modality?

Is Perceptual Learning Genuinely Perceptual?

This chapter argues that there are widespread changes in perception due to learning, and that these changes are genuinely perceptual rather than post-perceptual. The argument is abductive. It draws on philosophical introspection spanning several hundred years, evidence from psychology, and evidence from neuroscience. The argument is that when we look at these three different levels of analysis, the best overall explanation for their results is that perceptual learning occurs, is fairly widespread, and is genuinely perceptual rather than post-perceptual. One key piece of the argument is that neuroscientific perceptual learning experiments repeatedly show that there are changes very early on in the primary sensory cortices after perceptual learning tasks. Coupled with behavioral evidence from psychology and convergent philosophical introspection on the perceptual learning cases, this chapter argues that perceptual learning is genuinely perceptual, rather than post-perceptual.