• Sensation:  is the stimulus detection process by which our sense organs respond to and translate environmental stimuli into nerve impulses that are sent to the brain

• Perception: making “sense” of what our senses tell us—is the active process of organizing this stimulus input and giving it meaning

Sensory Processes

• Transduction:  is the process whereby the characteristics of a stimulus are converted into nerve impulses

• Psychophysics: studies relations between the physical characteristics of stimuli and sensory capabilities

• Absolute Threshold: the lowest intensity at which a stimulus can be detected 50 percent of the time

• Decision Criterion: a standard of how certain they must be that a stimulus is present before they will say they detect it

• Signal-Detection Theory: is concerned with the factors that influence sensory judgments

• Difference Threshold (just noticeable difference(jnd)): is defined as the smallest difference between two stimuli that people can perceive 50 percent of the time

• Weber’s law: states that the difference threshold or jnd is directly proportional to the magnitude of the stimulus with which the comparison is being made

• Sensory adaptation: the diminishing sensitivity to an unchanging stimulus

Vision

• Lens: an elastic structure that becomes thinner to focus on distant objects and thicker to focus on nearby objects

• Retina: a multi-layered light-sensitive tissue at the rear of the fluid-filled eyeball.

• Rods:  which function best in dim light, are primarily black-and-white brightness receptors

• Cones: are color receptors, function best in bright illumination

• Fovea: a small area in the center of the retina that contains no rods but many densely packed cones

• Visual Acuity: ability to see fine detail

• Photopigments: Rods and cones translate light waves into nerve impulses through the action of protein molecules

• Dark Adaption: the progressive improvement in brightness sensitivity that occurs over time under conditions of low illumination

• Young-Helmholtz trichromatic theory: there are three types of color receptors in the retina

• Hering’s opponent-process Theory: proposed that each of the three cone types responds to two different wavelengths

• Dual-Process Theory: combines the trichromatic and opponent-process theories to account for the color transduction process

• Feature Detectors: fire selectively in response to visual stimuli that have specific characteristics

Audition

• Frequency: the number of sound waves, or cycles, per second

• Hertz(Hz): the technical measure of cycles per second; 1 hertz equals 1 cycle per second

• Amplitude: refers to the vertical size of the sound waves—that is, the amount of compression and expansion of the molecules in the conducting medium

• Cochlea: a coiled, snail-shaped tube about 3.5 centimeters (1.4 inches) in length that is filled with fluid and contains the Basilar Membrane

• Basilar Membrane: a sheet of tissue that runs its length.

• Organ of Corti: contains about 16,000 tiny hair cells that are the actual sound receptors

• Frequency Theory of Pitch Perception: nerve impulses sent to the brain match the frequency of the sound wave

• Place Theory of Pitch Perception: suggesting that the specific point in the cochlea where the fluid wave peaks and most strongly bends the hair cells serves as a frequency coding cue

• Conduction Deafness:  involves problems with the mechanical system that transmits sound waves to the cochlea

• Nerve Deafness: caused by damaged receptors within the inner ear or damage to the auditory nerve itself

Taste and Smell: the Chemical Senses

• Gustation: the sense of taste

• Olfaction: the sense of smell

• Taste buds: chemical receptors concentrated along the tip, edges, and back surface of the tongue

• Olfactory Bulb: a forebrain structure immediately above the nasal cavity

• Pheromones: chemical signals found in natural body scents

  • Can affect human behavior in subtle ways

The Skin and Body Senses

• Gate Control Theory: proposes that the experience of pain results from the opening and closing of gating mechanisms in the nervous systems

• Kinesthesis: provides us with feedback about our muscles’ and joints’ positions and movements

• Vestibular sense: the sense of body orientation or equilibrium

Perception: The Creation of Experience

• Bottom-up Processing: the system takes in individual elements of the stimulus and then combines them into a unified perception

• Top-Down Processing:  sensory information is interpreted in light of existing knowledge, concepts, ideas, and expectations

• Inattentional Blindness: refers to the failure of unattended stimuli to register in consciousness

  • Backed up why you shouldn’t be on your phone while driving

• Gestalt Theories:

  • Figure-Ground relations: tendency to organize stimuli into a central or foreground figure and a background

  • Gestalt Theory of Perceptual Organization: similarity, proximity, closure, and continuity

    • Examples include the duck/rabbit image, is it a vase or two people kissing, etc

• Perceptual Schema: a mental representation or image containing the critical and distinctive features of a person, object, event, or other perceptual phenomena

• Perceptual set: a readiness to perceive stimuli in a particular way

• Perceptual Constancies: allow us to recognize familiar stimuli under varying conditions

Perception of Depth, Distance, and Movement

• Monocular Depth Cues: which require only one eye

  • Cues include patterns of light and shadow, linear perspective, interposition, height, relative size, motion parallax.

• Binocular Depth Cues: requires both eyes

  • Binocular Disparity: where each eye sees a slightly different image

  • Convergence: is produced by feedback from the muscles that turn your eyes inward to view a close object

• Stroboscopic movement: illusory movement produced when a light is briefly flashed in darkness, and then, a few milliseconds later, another light is flashed nearby

• Illusions: compelling but incorrect perceptions

• Critical Periods: during which certain kinds of experiences must occur if perceptual abilities and the brain mechanisms that underlie them are to develop normally