Smell, Taste, TOUCH & Hearing
Chapter 7
Sensation and Perception
SENSATION: the psychological experience associated with sound, light, or other simple stimulus and the initial information-processing steps by which sense organs and neural pathways take in stimulus information from the environment
PERCEPTION: the recognition, organization, and meaningful interpretation of sensory stimuli
Breakdown of the Sensory Systems
PHYSICAL STIMULUS: that in the environment that activates the sense organs
PHYSIOLOGICAL RESPONSE: pattern of electrical or chemical activity that occurs as a result of the stimulus
SENSORY EXPERIENCE: subjective sensation and perception experienced by the person
Physical stimulus
Physiological response
Sensory experience
Each Sensory System Has Distinct Receptors and Neural Pathways
SENSORY RECEPTORS: specialized structures (cells or tips of neurons) that respond to physical stimuli
SENSORY AREAS: areas of the brain’s cerebral cortex that receive and analyze input from the body’s senses
Sensory Transduction Concepts
TRANSDUCTION: process by which a receptor cell produces an electrical change in response to the energy of a physical stimulus
RECEPTOR POTENTIAL: the actual electrical charge that occurs in the receptor cell in response to the physical stimulus
SENSORY CODING: process by which information about the quality and quantity of a stimulus is preserved in the pattern of action potentials
SENSORY ADAPTATION: temporary decrease in sensitivity to sensory stimulation that occurs when a sensory system is stimulated for a period of time, and vice versa
Transduction and Coding for the Sense of Smell
Physical stimulus: ODORANTS
Sensory Receptors: olfactory receptor cells
Location: mucous membrane of the olfactory epithelium
Differences Among People in Olfactory Sensitivity
Women are more sensitive to smells than men
Sensitivity decreases with age
Genetic and environmental influences: ANDROSTENONE & differentiation learning
Discriminating Among Individuals by Smell
Smell plays a role in mother-infant bonding
Involved in mate selection (major histocompatibility complex)
PHEROMONES: a chemical that is released by an animal and that acts on other members of the species to promote some specific behavioral or physiological response Vomeronasal Organ
Anatomy and Physiology of Taste
Sensory receptors: taste receptor cells
Location: Tongue (Taste buds), roof of the mouth, entrance of the throat
Five Primary TastesSALTY• Best stimulus: NaCl
SOUR• Best stimulus: H+ ions
BITTER• Best stimulus: quinine
SWEET• Best stimulus: glucose/fructose
UMAMI• Best stimulus: Monosodium Glutamate
An Evolutionary Account of Taste Quality
What is edible (safe) and what is not (poisonous)?
Sour taste due to bacterial decay; bitter taste due to toxic compounds
Women and children are most sensitive to bitter
Neural Pathways for Pain
Physical stimuli: pressure vibration (to judge an
object’s roughness) temperature pain (events that
cause tissue damage)
Touch Sensory Receptors
PIC of skin surface
A-delta fibersC fibers
Sound as a Physical Stimulus AMPLITUDE LOUDNESS (Decibels)
FREQUENCY PITCH (Hertz)
High Amplitude Low Amplitude
Low Frequency High Frequency
How the Ear Works
The Inner Ear
Tectorialmembrane
Deafness and Hearing Aids
Conduction deafness occurs when the ossicles fail to move and transmit vibrations to the inner ear
Sensorineural deafness results from damage to the hair cells or auditory neurons
A COCHLEAR IMPLANT may be used to transmit electrical impulses directly to the cochlea by means of an implant
Von Bekesy (1961)