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

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Presentation on theme: " Sense organs  See, hear, taste, smell, touch, balance, and experience the world  Sensory receptor cells transmit sensation  Perception – interpreting."— Presentation transcript:


2  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

3  Transduction – translates one form of energy (incoming stimuli) into another (sensory information)  Receptor cells to neural impulses Sensation and Perception

4  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 Sensation and Perception

5 Vision A candle flame seen at 30 mi. on a clear, dark night Hearing The tick of a watch under quiet conditions at 20 ft. Taste One teaspoon of sugar in 2 gallons of water Smell 1 drop of perfume diffused into the entire volume of a 3 room apartment Touch The wing of a bee falling on your cheek from a height of 1 cm

6  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 Sensation and Perception

7  Light  Electromagnetic radiation  Waves - frequency  Wavelength – determines hues seen  Intensity – brightness  The more wavelengths in light, the less saturated or pure its hue is Sensation and Perception

8  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 Sensation and Perception

9 Cornea Iris Pupil Lens Ciliary muscle Retina Fovea Optic nerve

10 Cones Rods

11  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 Sensation and Perception

12  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 Sensation and Perception

13 Optic chiasm Optic nerve Blind spot

14  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 Sensation and Perception

15  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 Sensation and Perception

16 Trichromtic theory (Young-Helmholtz)

17  Color afterimages  Complementary colors – yellow and blue, red and green  Prolonged staring causes ghostly afterimage in complementary colors  Occurs in all for complementary colors Sensation and Perception

18  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 Sensation and Perception

19 Fast Slow Opponent-Process Theory (Hering)

20  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 Sensation and Perception

21 Color Blindness

22  A udition - 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 Sensation and Perception

23 Maximum level of industrial noise considered safe Characteristics of Sound Waves Loud thunder or rock concert Pain Threshold City bus Normal conversation Subway db Noisy automobile Absolute threshold of human hearing Quiet office Whisper Rocket launch

24  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 ) Sensation and Perception

25 Pinna External auditory canal Eardrum Hammer Anvil Stirrup Oval window Cochlea Round window Semicircular canals Nerve to brain Eustachian tube Outer earMiddle earInner ear

26 Cochlea Oval window Round window Basilar membrane Hair cells

27  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 Sensation and Perception

28  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 Sensation and Perception

29 The Skin Senses Pressure Free nerve endings Tactile discs hair Specialized end bulbs basket cell around hair Temperature


31  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 Sensation and Perception

32  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 Sensation and Perception

33 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

34  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 Sensation and Perception

35  Senses of gustation (taste) and olfaction (smell) differ from all other senses  Taste cells and papillae on tongue  Taste buds detect Sensation and Perception Sweetness - mostly sugars Sourness - mostly acids Saltiness - mostly salts Bitterness - toxins, chemicals Fattiness - fats

36 Surface of tongue Receptor cells Pore Bitter Sour Salty Sweet and fatty Sensory nerve fiber Taste

37  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 Sensation and Perception

38 Olfactory nerve to brain Olfactory epithelium Nasal cavity

39  Perception  Some unique aspects in different cultures  There is some common reality in shared world  Visual perception  Perceptual organization  Figure-ground  Continuity  Proximity Sensation and Perception Similarity Closure

40 Figure-Ground

41 Law of Continuity Law of Proximity

42 Law of Closure Law of Similarity

43  Perceptual Constancy  Brightness constancy  Color constancy  Size constancy  Shape constancy Sensation and Perception

44  Retina has two-dimensional surface  Monocular cues – perception of one eye  Texture gradient  Linear perspective  Superposition  Shadowing Sensation and Perception –Speed of movement –Aerial perspective –Accommodation –Vertical position

45  Binocular cues – perception with two eyes  Convergence  Retinal disparity  Visual Illusions  Ponzo illusion  Vertical-horizontal illusion  Color perception Sensation and Perception –Zollner illusion –Moon illusion –Poggendorf illusion

46 The Ponzo Illusion The Müller - Lyer Illusion

47 Visual Illusions Kanizsa square ED R

48  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 Sensation and Perception


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