Module 19 Review

REVIEW Vision: Sensory and Perceptual Processing

LEARNING OBJECTIVES

RETRIEVAL PRACTICE Take a moment to answer each of these Learning Objective Questions (repeated here from within this section). Then click the 'show answer' button to check your answers. Research suggests that trying to answer these questions on your own will improve your long-term retention (McDaniel et al., 2009).

19-1 What are the characteristics of the energy that we see as visible light? What structures in the eye help focus that energy?

What we see as light is only a thin slice of the broad spectrum of electromagnetic energy. The portion visible to humans extends from the blue-violet to the red light wavelengths. After entering the eye and being focused by a lens, light energy particles strike the eye’s inner surface, the retina. The hue we perceive in a light depends on its wavelength, and its brightness depends on its intensity.

19-2 How do the rods and cones process information, and what is the path information travels from the eye to the brain?

Light entering the eye triggers chemical reaction in the light-sensitive rods and color-sensitive cones at the back of the retina, which converts light energy into neural impulses. After processing by bipolar and ganglion cells, neural impulses travel from the retina through the optic nerve to the thalamus, and on to the visual cortex.

19-3 How do we perceive color in the world around us?

According to the Young-Helmholtz trichromatic (three-color) theory, the retina contains three types of color receptors. Contemporary research has found three types of cones, each most sensitive to the wavelengths of one of the three primary colors of light (red, green, or blue).
     Hering’s opponent-process theory proposed three additional color processes (red-versus-green, blue-versus-yellow, black-versus-white). Research has confirmed that, en route to the brain, neurons in the retina and the thalamus code the color-related information from the cones into pairs of opponent colors.
     These two theories, and the research supporting them, show that color processing occurs in two stages.

19-4 Where are feature detectors located, and what do they do?

Feature detectors, located in the visual cortex, respond to specific features of the visual stimulus, such as shape, angle, or movement. Supercell clusters in other critical areas respond to more complex patterns.

19-5 How does the brain use parallel processing to construct visual perceptions?

Through parallel processing, the brain handles many aspects of vision (color, movement, form, and depth) simultaneously. Other neural teams integrate the results, comparing them with stored information and enabling perceptions.

19-6 How did the gestalt psychologists understand perceptual organization, and how do figure-ground and grouping principles contribute to our perceptions?

Gestalt psychologists searched for rules by which the brain organizes fragments of sensory data into gestalts (from the German word for “whole”), or meaningful forms. In pointing out that the whole may exceed the sum of its parts, they noted that we filter sensory information and construct our perceptions.
     To recognize an object, we must first perceive it (see it as a figure) as distinct from its surroundings (the ground). We bring order and form to stimuli by organizing them into meaningful groups, following such rules as proximity, continuity, and closure.

19-7 How do we use binocular and monocular cues to perceive the world in three dimensions, and how do we perceive motion?

Depth perception is our ability to see objects in three dimensions and judge distance. The visual cliff and other research demonstrate that many species perceive the world in three dimensions at, or very soon after, birth. Binocular cues, such as retinal disparity, are depth cues that rely on information from both eyes. Monocular cues (such as relative size, interposition, relative height, relative motion, linear perspective, and light and shadow) let us judge depth using information transmitted by only one eye.
     As objects move, we assume that shrinking objects are retreating and enlarging objects are approaching. A quick succession of images on the retina can create an illusion of movement, as in stroboscopic movement or the phi phenomenon.

19-8 How do perceptual constancies help us construct meaningful perceptions?

Perceptual constancy enables us to perceive objects as stable despite the changing image they cast on our retinas. Color constancy is our ability to perceive consistent color in objects, even though the lighting and wavelengths shift. Brightness (or lightness) constancy is our ability to perceive an object as having a constant lightness even when its illumination—the light cast upon it—changes. Our brain constructs our experience of an object’s color or brightness through comparisons with other surrounding objects.
     Shape constancy is our ability to perceive familiar objects (such as an opening door) as unchanging in shape. Size constancy is perceiving objects as unchanging in size despite their changing retinal images. Knowing an object’s size gives us clues to its distance; knowing its distance gives clues about its size, but we sometimes misread monocular distance cues and reach the wrong conclusions, as in the Moon illusion.

19-9 What does research on restored vision, sensory restriction, and perceptual adaptation reveal about the effects of experience on perception?

Experience guides our perceptual interpretations. People blind from birth who gained sight after surgery lack the experience to visually recognize shapes, forms, and complete faces.
     Sensory restriction research indicates that there is a critical period for some aspects of sensory and perceptual development. Without early stimulation, the brain’s neural organization does not develop normally.
     People given glasses that shift the world slightly to the left or right, or even upside down, experience perceptual adaptation. They are initially disoriented, but they manage to adapt to their new context.

TERMS AND CONCEPTS TO REMEMBER

RETRIEVAL PRACTICE Match each of the terms on the left with its definition on the right. Click on the term first and then click on the matching definition. As you match them correctly they will move to the bottom of the activity.

Question

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