【Psychology and Life】Chapter 04 — Main Points
* All the following abstractions are excerpted from <Psychology and Life>, Richard J. Gerrig & Philip G. Zimbardo, 19th edition
Chapter 04 — Sensation and Perception.
— Perceptual Knowledge of the World
The task of perception is to determine what the distal (external) stimulus is from the information contained in the proximal (sensory) stimulus.
Psychophysics investigates psychological responses to physical stimuli. Researchers measure absolute thresholds and just noticeable differences between stimuli.
Signal detection allows researchers to separate sensory acuity from response biases.
Researchers in psychophysics have captured the relationship between physical intensity and psychological effect with mathematical functions.
Sensation translates the physical energy of stimuli into neural codes via transduction.
— The Visual System
Photoreceptors in the retina, called rods and cones, convert light energy into neural impulses.
Ganglion cells in the retina integrate input from receptors and bipolar cells. Their axons form the optic nerves that meet at the optic chiasma.
Visual information is distributed to several different areas of the brain that process different aspects of the visual environment such as how things look and where they are.
The wavelength of light is the stimulus for color.
Color sensations differ in hue, saturation, and brightness.
Color vision theory combines the trichromatic theory of three color receptors with the opponent-process theory of color systems composed of opponent elements.
— Hearing
Hearing is produced by sound waves that vary in frequency, amplitude, and complexity.
In the cochlea, sound waves are transformed into fluid waves that move the basilar membrane. Hairs on the basilar membrane stimulate neural impulses that are sent to the auditory cortex.
Place theory best explains the coding of high frequencies, and frequency theory best explains the coding of low frequencies.
To compute the direction from which the sound is arriving, two types of neural mechanisms compute the relative intensity and timing of sounds coming to each ear.
— Your Other Senses
Smell and taste respond to the chemical properties of substances and work together when people are seeking and sampling food.
Olfaction is accomplished by odor-sensitive cells deep in the nasal passages.
Taste receptors are taste buds embedded in papillae, mostly in the tongue.
The cutaneous (skin) senses give sensations of pressure and temperature.
The vestibular sense gives information about the direction and rate of body motion.
The kinesthetic sense gives information about the position of body parts and and helps coordinate motion.
Pain is the body’s response to potentially harmful stimuli.
The physiological response to pain involves sensory response at the site of the pain stimulus and nerve impulses moving between the brain and the spinal cord.
— Organizational Processes in Perception
Perceptual processes organize sensations into coherent images and give you perception of objects and patterns.
Both your personal goals and the properties of the objects in the world determine where you will focus your attention.
The Gestalt psychologists provided several laws of perceptual grouping, including proximity, similarity, good continuation, closure, and common fate.
Perceptual processes integrate over both time and space to provide an interpretation of the environment.
Binocular, motion, and pictorial cues all contribute to the perception of depth.
You tend to perceive objects as having stable size, shape, and lightness.
Knowledge about perceptual illusions can provide constraints on ordinary perceptual processes.
— Identification and Recognition Processes
During the final stage of perceptual processing — identification and recognition of objects — percepts are given meaning through processes that combine bottom-up and top-down influences.
Ambiguity may arise when the same sensory information can be organized into different percepts.
Context, expectations, and perceptual sets may guide recognition of incomplete or ambiguous data in one direction rather than another equally possible one.