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)