Chapter 5 Notes PDF

But eyes also deceive us in the way that Descartes suggested: the workings of the senses are to a large extent autonomous and, thus, often produce erroneous perceptual inferences about what the real world actually is. perception begins much earlier than the recognition of objects of interest; it be...

But eyes also deceive us in the way that Descartes suggested: the workings of the senses are to a large extent autonomous and, thus, often produce erroneous perceptual inferences about what the real world actually is. perception begins much earlier than the recognition of objects of interest; it begins with the “dull sensations what’s really important about perception occurs within a window of time that is much shorter than 1s Perception is about the organization of this kaleidoscope into the objects that form our understanding of the world Bottom-up: it is bottom-up in the sense that it is driven by the low-level features of the visual world, the features which we are hardwired to detect Neisser: thought that perception should not be seen as the grasping of information via the sense organs and its transformation through successive stages of processing following computer-like algorithms Neisser’s definition: perception occurs over time to serve the goals of the perceiver, who anticipates much of what is to be perceived, integrating recent and incoming streams of information Affordances: it is as if your perceptual processes are determined by what the objects “mean” it seems that we focus on what is important to us while neglecting much of what is not when you open your eyes randomly at a particular scene, most likely what you see are the objects of your interest, perhaps the “value rich" ones Affordances need to rely on what objects are “used for”, or what they "say" to us Ecological approach: makes intuitive sense because we seem to connect to objects of interest almost as immediately as we lay our eyes on them: we see a coffee mug and it seems hard to dissociate it from the very idea of having a coffee it attempts to deny the role played by internal mechanisms in the process of decoding incoming information by assuming that information about objects and scenes are picked up “directly”, by what they "say" key difference is that Gibson also allowed for misperception: a thing says what it is, but a thing can also deceive us But the mechanisms that underlie that kind of certainty play a fundamental role in the process of understanding what you see and, ultimately, in the “benefit or injury” it yields object only has a meaning (or affordance) once it is decoded How do you “frame” your anticipations? In other words, the anticipation of incoming information requires internal representations of what is to be expected, which requires some criterion on what is to be represented to be expected, and so on. Top-down: criterion that selects your anticipations, except for what the incoming information—and its successive transformation upstream—propose But your beliefs cannot determine what you see Perceptual inferences: what you ultimately get is the product of complex perceptual computations distinction— between decoding the incoming information via perceptual inferences and understanding or cognizing what is seen—to be key to cognitive science This distinction between perception as an input-driven mechanism and other domains of analysis of the visual world deeply rooted in the common histories of philosophy and psychology Hume who expressed more persuasively the idea that perceiving and understanding are very distinct processes Descartes, a rationalist, about a century before Hume, had already put forth the notion that “perceiving” and “cognizing” are different faculties of the mind there is in fact a world out there (I am sort of certain about that), and that this world out there is decoded and encoded into particular forms of representations that allow for the brain to understand the world and guide our actions A theory of vision proper requires an understanding that the 3-D world is projected onto our retinas as a 2-D array of light intensities, which needs to be transformed— or “interpreted”—as a 3-D world again Separating “perceiving” from “cognizing” will lead us to determine the kinds of mental processes (and implicit knowledge) that occur independently of our explicit knowledge of the world this will also lead us to understand which processes (and representations) are fixed and cannot be change = hardwired in the brain recognition of objects and scenes and our acting upon them are just the final products of visual computations it is in visual perception where it becomes more obvious fovea is where detailed information about the world is gathered that we constantly move our eyes when scanning scenes, reading, focusing attention, and even avoiding to look directly at someone while keeping him or her in the “periphery” the processes by which the physical properties of the world (light, sound) are transformed into code that the brain is able to compute do not explain the nature perceptual and cognitive processes The retina can only signal the contrast between those objects and their backgrounds, only the internal features that are in fact value-free. The functions proper—how you recognize an object or a face from the patterns of light—requires a computational theory together with the rules and representations that the system employs the images are inverted (upside down), but they are also “split” in half by each side of each one of the two retinas, that is, each half of each retina has access to the contralateral visual hemifield The superior colliculus plays a key role in visual attention and action. It contains a map of the visual field, which helps guide the eyes (and head) to move to particular locations so that the area of interest in the field can be detected by the fovea