Sense organs See, hear, taste, smell, touch, balance, and experience the world Sensory receptor cells transmit sensation Perception – interpreting

Sense organs See, hear, taste, smell, touch, balance,

and experience the world Sensory receptor cells transmit

sensation Perception – interpreting information

and forming images Stimulus

Sensation and Perception

Transduction – translates one form of energy (incoming stimuli) into another (sensory information)

Receptor cells to neural impulses


Threshold – lower limits Absolute threshold – smallest to be

detected Difference threshold – smallest

difference between 2 stimuli to be detected 50% of time

Sensory adaptation – one’s sensitivity to a stimulus varies from time to time Fatigue, inattention, repeated exposure


VisionA candle flame seen at 30 mi. on a clear, dark night

Hearing The tick of a watch under quiet conditions at 20 ft.

TasteOne teaspoon of sugar in 2 gallons of water

Smell1 drop of perfume diffused into the entire volume of a 3 room apartment

TouchThe wing of a bee falling on your cheek from a height of 1 cm

Psychophysics – studies sensory-related matters

Weber’s law – amount of change needed for detection 50% of time is always in direct proportion to intensity of original stimulus


Light Electromagnetic radiation

Waves - frequency

Wavelength – determines hues seen

Intensity – brightness

The more wavelengths in light, the less saturated or pure its hue is


Light passes through cornea Iris regulates light through pupil into

lens Lens held in place by ciliary muscle Retina has rods and cones for

receptors Fovea – center of retina Visual acuity – clarity and sharpness


Cornea

Iris

Pupil

Lens

Ciliary muscle

Retina

Fovea

Optic nerve

Cones

Rods

Rods Not located in fovea Responsible for peripheral vision Hundreds of times more sensitive to

light than cones Produce images perceived with less

visual acuity than cones Do not detect color


Cones Give brain more precise

information Code information about color Respond only in bright light

Optic nerve – has no cones or rods

Blind spot – no visual reception in optic nerve

Optic chiasm


Optic chiasm

Optic nerve

Blind spot

Dark adaptation Receptors receive new supply of chemicals After 30 minutes in the dark - level of

sensitivity about 100,000 times greater than in bright light

Light adaptation Rods and cones highly responsive –

overload Bleaching out of receptor chemicals occurs


Night blindness – vitamin A deficiency

Color vision Wavelengths determine colors seen Any color can be created from

combinations of red, blue, and green

Trichromatic theory – 3 kinds of cones in eye responding mostly to light in either red, blue, or green range of wavelengths


Trichromtic theory (Young-Helmholtz)

Color afterimages Complementary colors – yellow and blue,

red and green

Prolonged staring causes ghostly afterimage in complementary colors

Occurs in all for complementary colors


Opponent-process theory

Two kinds of color-processing mechanisms receiving messages from three kinds of cones

Each mechanism responds in opposite ways corresponding to two pairs of complementary colors


Fast FastSlowSlow

Opponent-Process Theory (Hering)

Affects about 8% of males, 1% of females

Partial color blindness – difficulty distinguishing between two colors Red-green blindness due to genetic defect

Yellow-blue blindness due to absence of blue pigment in cones


Color Blindness

Audition - detection of sound waves

Frequency of cycles Compression – increased density of

waves Rarefaction – reduced density of waves Determines pitch of sound Intensity measured in decibel (db)

units Prolonged exposure to over 85 db causes

hearing loss

Timbre – quality of sound


Maximum level of industrial noise considered safe

Characteristics of Sound Waves

20 40 60 80 100 1600 120 180140

Loud thunder or rock concert

Pain Pain ThresholdThreshold

City bus

Normal conversation

Subway

db

Noisy automobile

Absolute threshold of human hearing

Quiet office

Whisper Rocket launch

Outer ear Pinna – external part of ear that collects

sound External auditory canal – connects outer

and middle ear

Middle ear Cardum – tympanic membrane; 1st

structure Eardrum - outermost structure of middle

ear Passes vibration to interconnected bones

(hammer, anvil, and stirrup)


Pinna

External auditory canal

Eardrum

Hammer Anvil

Stirrup

Oval window

Cochlea

Round window

Semicircularcanals

Nerve tobrain

Eustachiantube

Outer ear Middle ear Inner ear

Cochlea

Oval window

Round window

Basilar membrane

Hair cells

Inner ear Oval window – eardrumlike structure at

end of cochlea Round window – eardrumlike structure at

other end of cochlea Basilar membrane – forms floor for ear’s

sensory receptors Organ of Corti – contains hairlike receptor

cells


Orientation and movement Vestibular organ – 2 sets of sensory

structures Semicircular canals Saccule and utricle

Kinesthetic receptors – throughout body Skin senses

Pressure sensitivity Temperature sensitivity


The Skin Senses Pressure

Free nerve endings

Tactile discs

hair

Specialized end bulbs

basket cell around hair

Temperature

BA C D E G

Braille Alphabet H I

U W

F

S T X Y ZV

L NJ K O P Q RM

Nerve endings in body act as nocioceptors Neural messages transmitted along two

distinct pathways Rapid – detects first pain sensation Slow – detects second long-lasting pain

Endorphins and endogenous morphine


Nerve endings in body act as nocioceptors Pain gates regulate pain signals in 3 areas

Brain stem – gate-control theory of pain Spinal cord Peripheral regulation of pain

Phantom limbs Up tp 70% of amputees experience this


Direction of pain message

neuro-transmitter molecules in axon of slow-pain neuron

Endorphin receptor

Axon of inhibitory pain gate neuron

endorphin

Neuron in slow-pain fiber

Inhibitory pain gate neuron

Stimulation of endorphin receptors inhibits firing of axon of slow-pain neuron

Close-up view of inhibitory pain gates

Somatosensory area of cortex

Limbric system

Area of pain gates

Pathway of fast-pain fibers

Pathway of slow-pain fibers

Gate-control theory of pain

Bariba society – cultural emphasis on pain Tolerate pain easily Calm response to pain is part of Bariba pride Pregnant women don’t show labor pain

reaction, experience labor pain and birth alone

Medical professionals can overestimate or underestimate effects of pain if impact of culture is not considered


Senses of gustation (taste) and olfaction (smell) differ from all other senses Taste cells and papillae on tongue Taste buds detect


Sweetness - mostly sugars Sourness - mostly acidsSaltiness - mostly saltsBitterness - toxins, chemicalsFattiness - fats

Surface of tongue

Receptor cells

Pore

Bitter

Sour

Salty

Sweet and fatty

Sensory nerve fiber

Taste

Olfaction Olfactory epithelium – top of nasal cavity Pheromone detection of sweat and urine

Vomeronasal organ Influence human female reproductive cycles Inhalation of male sex hormone and mood

changes Males may respond to sex hormones


Olfactory nerve to brain

Olfactory epithelium

Nasal cavity

Perception Some unique aspects in different cultures There is some common reality in shared

world Visual perception

Perceptual organization Figure-ground Continuity Proximity


• Similarity • Closure

Figure-Ground

Law of Continuity

Law of Proximity

Law of Closure

Law of Similarity

Perceptual Constancy Brightness constancy

Color constancy

Size constancy

Shape constancy


Retina has two-dimensional surface

Monocular cues – perception of one eye

Texture gradient Linear perspective Superposition Shadowing


– Speed of movement

– Aerial perspective

– Accommodation

– Vertical position

Binocular cues – perception with two eyes Convergence Retinal disparity

Visual Illusions Ponzo illusion Vertical-horizontal

illusion

Color perception


– Zollner illusion– Moon illusion– Poggendorf illusion

The Ponzo Illusion

The Müller - Lyer Illusion

Visual Illusions

Kanizsa square

EDR

Integrate and interpret information from multiple senses simultaneously Limited ability and accident occurrence

Motivation, Emotion, and Perception Motivation and emotions influence perception

Past experiences influence all perceptions



Documents

Sense organs See, hear, taste, smell, touch, balance, and experience the world Sensory receptor cells transmit sensation Perception – interpreting