Presentation on theme: "1. Contrast the processes of sensation and perception."— Presentation transcript:
1 1. Contrast the processes of sensation and perception. Objectives:1. Contrast the processes of sensation and perception.2. Distinguish between absolute and difference thresholds, and discuss research findings on subliminal stimulation.3. Describe the phenomenon of sensory adaptation and explain its functional value.
2 -done by our sensory organs Perception SensationSensationSensation- process of detecting physical energy from the environment and encoding it into neural signals-done by our sensory organsPerceptionprocess of selecting, organizing, and interpreting our sensations-done by our brains
3 SensationOur sensory and perceptual processes work together to help us sort out complexprocesses
4 Sensation Bottom-Up Processing processing that begins with the sense receptors and works up to the brain’s integration of sensory informationTop-Down Processinginformation processing guided by higher-level mental processesas when we construct perceptions drawing on our experience and expectations
5 Sensation- Basic Principles -as humans we exist in a sea of energy-some we are aware of, some we aren’tpsychophysics-the study of how this physical energy around us relates to our psychological experience<<EARLY SCHOOL OF PSYCHOLOGY>>
6 Sensation- Thresholds Absolute Thresholdminimum stimulation needed to detect a particular stimulus 50% of the time
7 Sensation- Thresholds vision-we can see a candle flame from 30 miles on a clear, dark night (granted there are no physicalobstructions) hearing-we can hear a watch ticking in a silent room from 20 feet away touch- we can feel the wing of a fly falling on our face from a very close distance smell-we can smell a single drop of perfume in a 3 room apartmenttaste-we can taste a teaspoon of sugar diluted in 2 or 3 gallons of water ex. Hearing tests
8 Sensation- Thresholds Signal Detection Theorypredicts how and when we detect the presence of a faint stimulus (signal) amid background stimulation (noise)assumes that there is no single absolute thresholddetection depends partly on person’sExperience/ expectations/ motivation/ level of fatigue>seeks to explain why people respond differently to the same stimuli, and why the same person’s reactions vary as circumstances change
9 Sensation- Thresholds Difference Thresholdminimum difference between two stimuli required for detection 50% of the time-aka the just noticeable difference (jnd) -the difference threshold increases with the magnitude of the stimulus
10 Sensation- Thresholds Weber’s Law- to perceive as different, two stimuli must differ by a constant minimum percentage (rather than amt)light intensity- 8%weight- 2%tone frequency- 0.3%Sensory adaptation- diminished sensitivity as a consequence of constant stimulationWhy??
11 Sensation- Subliminal Stimulation subliminal message- stimulus that lies below one’s absolute threshold for conscious awarenessWe can detect some subliminal messagesHow is that?-because absolute thresholds involvedetecting the stimulus 50% of the timeDoes this mean we can be subliminally persuaded?<<NO>>>>CBC Sunday night Study..”Telephone Now”>>subliminal tape study>>John Krosnick 1992
12 Sensation- Thresholds 255075100LowAbsolutethresholdMediumIntensity of stimulusPercentageof correctdetectionsSubliminalstimuliSubliminalWhen stimuli are below one’s absolute threshold for conscious awareness
14 Vision4. Explain the visual process, including the stimulus input, the structure of the eye, and the transduction of light energy.Describe the 2 major theories of color vision.Explain issues with visual acuity and examine the afterimage effect in the context of opponent process theory.14
15 VisionTransduction-process by which our sensory systems convert stimulus energy into neural messagesA. The Stimulus for Visionlighttravels in electromagnetic waveswe only see visible portion of the light spectrumROY G. BIV2 physical characteristics of light that determine our sensory experience of them1. wavelength-distance from one wavepeak to the nextdet frequencydetermines the hue-color2. amplitude-height of wavedetermines the intensity or brightness of the wave
18 Vision- The Eyelight enters through the cornea (a transparent protector- bends light)pupil –small adjustable opening of the eye determines the amount of light let in (black part of eye)Iris-muscle that controls the amt of light that enters the pupil (colored pt of eye)lens -behind the pupilit focuses light rays by adjusting its curvature – process known as accommodationlens focus light onto the retina -the light sensitive inner surface of our eyes
19 Vision- The EyeRetina contains photoreceptors (rods and cones) which convert light energy into neural impulses <<pt of transduc in vis>>these impulses carried by optic nerve to the brain where they are constructed into full imagesRods-detect black, white, and graynecessary for peripheral and twilight visionCones-detect fine-detail and give rise to color sensationsconcentrated around center of retina (fovea – central point of focus)>>exp why the pupil must open to see in dark-b/c rods are on the periphery of retina
20 Vision Cones-6 million Rods-120 million We can see fine detail in color but can see black and white better in dim light…why?Enter bipolar cellsCones – many have their own bipolar cells assigned to them (more specific info transmitted)Rods-share bipolar cells so many can team up and pool their energy to transmit in dim light
21 Vision- Receptors Receptors in the Human Eye Cones Rods Number Location inretinaSensitivity indim lightColor sensitive?YesLowCenter6 millionNoHighPeriphery120 million
22 Visionwhen light strikes the rods and cones of the retina it causes a reaction that stimulates the optic nervenerve that carries neural impulses from the eye to the brainblind spot-the area where the optic nerve leaves the eye is devoid of photoreceptorsP 203 figure 5.8
26 Vision Acuity- the sharpness of vision Nearsightedness- nearby objects seen more clearly than distant objects because distant objects in front of retinaFarsightedness- faraway objects seen more clearly than near objects because the image of near objects is focused behind retina
27 VisionFar Nearsighted Normal (Short eyeball) (Long eyeball)
28 Visual Information Processing Feature Detectors (David Hubel & Torsten Wiesel 1979)nerve cells in the brain that respond to specific featuresshapeangleMovementFacial Recognition – 30% of cortexTemporal Lobe involved in facial recog (see p 205)StimulusCell’sresponses
29 Visual Information Processing *FYI-Facial rec: 30% of cortex (temp lobe heav inv)Sensorimotor skills – far moreParallel Processingsimultaneous processing of several aspects of a problem simultaneously>>Brain divides visual scene into subdivisions>They are all processed in parallel and combined into a whole.
30 Young and Helmholtz’s Trichromatic (three color) Theory three different retinal color receptorsRed, green,BlueWhen combinations are stimulated, we see other colors
31 Color-Deficient Vision People who suffer red-green blindness lack functioning red or green sensitive conesWell if Yellow is a mix of green & red, then how can c.b. see yellow?Enter Ewald Hering’s Opponent Process Theory
32 Visual Information Processing Ewald Hering’s Opponent-Process Theory- opposing retinal processes enable color vision“ON” “OFF”red greengreen redblue yellowyellow blueblack whitewhite blackNeurons in the retina & thalamus turned on by one of these colors are turned off by the opposite colorWhy we cannot see greenish red
34 Visual Information Processing Color ConstancyPerceiving familiar objects as having consistent color, even if changing illumination alters the wavelengths reflected by the objectColor Sensation is a Subjective experience – context plays a role in the processEx. apple in fruit bowl – color remains constant as lighting shifts
35 Audition7. Explain the auditory process, including the stimulus input and the structure and function of the ear.8. Explain the place and frequency theories of pitch perception, and describe how we locate sounds.9. Discuss the nature and causes of hearing loss, and describe the effects of noise on hearing and behavior.
36 Audition -audition-sense of hearing Sound Waves -our ears detect changes in air pressure caused by sound waves and transform them into neural impulses that our brains decode as sounds-amplitude/height determines the loudness (measured in decibels)Abs Threshold – defined as 0 dBEvery 10 decibel increase represents a tenfold increase in so-prolonged exposure > 85 decibels = hearing loss (sensorineural) -- Rock Concerts =140 dB
38 Auditionfrequency-(the # of wavelengths that pass a point per second) determines Pitchpitch –a tone’s highness or lownesslonger the wave/lower the frequency/lower the pitchshorter the wave/higher the frequency/higher the pitch(1 cycle/ sec =1 Hz; humans detect 20-20k Hz)Volume-det by amplitude
39 Audition- The Ear Outer Ear the visible part-- channels sound waves through the auditory canal to the eardrum(gateway to the middle ear)
40 Audition- The Ear Middle Ear Conducts eardrum’s vibrations through the hammer, anvil, and stirrup(smallest bone in body), which in turn stimulate the cochleaInner Ear (cochlea, semicircular canals, vestibular sacs)contains the cochlea-a coiled, bony, fluid-filled tube, which triggers nerve impulsescochlea contains the basilar membrane which is lined with tiny hair cells (16k v 130 mil rods/cones)-when the fluid in the cochlea vibrates -it stimulates these hair cells which triggers impulse in adjacent nerve fibers, which connect to the auditory nerve (TRANSDUCTION)
41 Pitch Perception Place Theory (Herman von Helmholtz) pitch we hear is det by place where the cochlea’s membrane is stimulated (place of vib det pitch)Hi freq waves produce large vib near beg of cochlea’s membrane; low near end>>brain: can det pitch by recog place on membrane from which it receives neural signalsProblem: Low pitched sounds don’t neatly localize on basilar membraneEnter Frequency Theorythe theory that the rate of nerve impulses traveling up the auditory nerve matches the frequency of a tone, thus enabling us to sense its pitch
42 Pitch Perception Frequency Theory Cont’d Brain reads pitch from frequency of neural impulses b/c neural impulses are triggered at same rate as sound wave(100 waves/ sec – 100 pulses/ sec)(note: humans detect sounds 20-20k Hz)Problem: Neurons can only fire 1000x/sec(Freq Th doesn’t explain how hi pitch is det)>>>>Volley Principle-workgroups of neural cells synchronize alternate firing & reloading(remember refractory period/ resting pause from Ch 2)
43 Hair cells activate neural impulses in neurons on Organ of Corti-
44 Sound Localization (2004 AP Essay Q) Sound travels at 750 miles per hour
45 Hearing Loss Conduction Hearing Loss Sensorineural/ Nerve Hearing Loss Inability to conduct vibrations due to eardrum puncture or damage to middle ear bones (digital hearing aids amp vib)Sensorineural/ Nerve Hearing Lossdamage to the cochlea’s receptor cells or to the auditory nerve, aging, loud noise/music, diseaseCoch implant (translates sound into neural imp)Won’t work in deaf adults who’ve spent a life w/o hearing? WHY NOT??????
46 Deaf CultureDeaf Culture-Nat’l Assoc of Deaf – “deafness isn’t a disability”>>objects to using cochlear implants in children who were deafened before learning to speak>>deafness could be considered “visual enhancement” v “hearing impairment”Auditory Cortex in deaf is sensitive to touch and visual inputHelen Keller – visual + aud cort sensitive to touch.FYI - Older adults have more trouble hearing high pitched sounds but are okay w/ low pitch… Why?Degeneration near beginnning of basilar membraneWhich th does this spt?Place Theory
47 Aging EffectsDet of high frequencies difficult in older people
48 Other Senses10. Describe the sense of touch, and explain the basis of pain.11. Describe the senses of taste and smell, and comment on the nature of sensory interaction.12. Distinguish between kinesthesis and the vestibular sense.
49 Touch 4 Separate Skin Senses pressure only skin sensation with identifiable receptorswarmthcoldPainRelnshp b/w warmth, cold, pain and receptors that respond to them remains a mystery.
50 Touch Other skin sensations are variations of the basic 4 Stroking adjacent pressure spots = tickleGentle stroking of pain spot = itching sensation
51 Pain pain is way of telling us that something is wrong >>people born w/o ability to feel pain die young (excess joint strain, infections from not shifting)pain is a sense, but the brain has a big effect on it as wellex. Phantom limb- 7 out of 10 amputees report pain ormovement in their nonexistent limbsEx. Placebo effectFyi-no single stimulus that triggers pain & no special receptors>>low pain stimuli can produce other sensationswarmth, coolness, smoothness, roughness
52 Pain Gate-Control Theory (Ronald Melzack & Patrick Wall) theory that the spinal cord contains a neurological “gate” that blocks pain signals or allows them to pass on to the brain“gate” opened by the activity of pain signals traveling up small nerve fibers“gate” closed by activity in larger fibers or by information coming from the brain (ie. endorphins)in theory you can treat pain by stimulating larger nerve fibers (massage, muscle stim, acupuncture)>>cause “gate closing” activity in large neural fibers>>Lamaze method of Pain Control combines relaxation, counterstimulation & distraction
53 Pain Brain’s role in pain cont’d--- Pain gate closed by endorphins eg Ohio St B-Ball player finishing game w/ broken neckBrain can also produce pain when no physical ailment is observedBrain’s Recording of Pain (exp memories of pain)Brain records peak moment of pain and how much is felt at end of experienceDaniel Kahneman 1993>>2 trials– trial 1 -put hand in cold H2O for 60 sectrial 2 - put hand in cold H2O for 60 sec + then immediately switch to slightly less cold for 30 secSubjects said they’d rather rep T 2Implications for med procedures (ie. Colon exams)
54 Pain More on Brain’s Role Roger Urlich 1994- Surgery patients assigned to rooms looking out on trees – less pain med & faster discharge than patients in identical rooms w/ a view of brick wall
55 Taste Did u know?-alc & smk dec taste sens also called gustatory sense involves 4 basic sensationssweet, sour, salty, and bitter (more recently: umami <meaty>)Taste & Smell are a chemical senses (unlike vis & aud)200+ taste buds on top & sides of tongue, each w/ a pore that catches food molecule that is sensed by taste receptors w/in pore (10-20k taste recep)each type of sensation has its own specialized taste budstaste receptors reproduce themselves about every 1 to 2 weeksage taste buds sensitivity “tongue plasticity” – if 1 side damaged, other side becomes supersensitiveIf no tongue, can still taste – tastebuds on top & back of mouth
56 Taste Did u know?-alc & smk dec taste sens Sensory Interaction one sense influences anotherespecially true with taste and smell>>people who’ve lost sense of smell think they’ve lost taste>>can’t taste when have a coldBest eg of S.I.:>>SMELL + TASTE + TEXTURE = FLAVOR
57 Smell Taste & Smell: “chemical senses” also called olfaction Molecules of substances reach 1 of 5 mil receptor cells in olfactory membraneolfactory nerve carries signals to the brain (olfactory cortex)(the one sense not routed through the thalamus at top of brainstem)>>still a mystery how exactly olf rec cells workodors can evoke strong memories & feelings.. WHY?Hotline b/w olf cortex limbic system (seat of emotion & memory)Makes EVOL sense>>olf cortex evolved first – mammalian ancestors smelled food and predators (rest of cortex development came later – ie. Assoc areas)Papillae-visible bumps on tongue that contain taste buds
59 Age, Sex and Sense of Smell WomenMenAge Group432Numberof correctanswersWomen and young adultshave best sense of smell
60 Body Position and Movement Kinesthesis- system for sensing the position and movement of individual body partsReceptors located in muscles, tendons, and joints athletes-strong kinesthetic senseVestibular Sense-the sense of body movement and position, including the sense of balancebased in the inner ear (semi-circular canals, vestibular sacs) head mvmt triggers fluid to stimulate hair-like receptors in these organs which sends msgs to cerebellum (rem balance & voluntary mvmt)>>exp why if head is off balance, whole body is off>>after spinning, neither fluid nor kinesth receptors immediately return to neutral ---- why you still feel like you’re spinning