UNIT IV SENSATION AND PERCEPTION Sensation Sensation a

UNIT IV SENSATION AND PERCEPTION

Sensation * §Sensation §a process by which our sensory receptors and nervous system receive and represent stimulus energy §(sensory stimuli > transduction to neural message > brain) §Perception §a process of organizing and interpreting sensory information, enabling us to recognize meaningful objects and events

Sensation * §Our sensory and perceptual processes work together to help us sort out complex processes

*Sensation § Bottom-Up Processing § analysis that begins with the sense receptors and works up to the brain’s integration of sensory information § Top-Down Processing § information processing guided by higher-level mental processes § as when we construct perceptions drawing on our experience and expectations All 4 s will apply each term to a children’s story or movie…

*Sensation- Basic Principles §Psychophysics § study of the relationship between physical characteristics of stimuli and our psychological experience of them § Light- brightness § Sound- volume § Pressure- weight § Taste- sweetness Using sensory details, imagine and describe how you experience the following stimuli: • Sunshine through your window at 5: 45 a. m • Loud classical music during class • Sour Patch Kids while watching a movie • A large hammer in your hand

*Sensation Thresholds § Absolute Threshold § minimum stimulation needed to detect a particular stimulus 50% of the time (Ex: passing car) § In partners or trios, come up with another example to explain to the class § Difference Threshold § minimum difference between two stimuli required for detection 50% of the time (Ex: flower color) § just noticeable difference (JND) § In partners or trios, come up with another example to explain to the class

*Sensation- Thresholds §Signal Detection Theory § predicts how and when we detect the presence of a faint stimulus (signal) amid background stimulation (noise) § assumes that there is no single absolute threshold because: § detection depends partly on person’s: Experience – Expectations -Motivation -Level of fatigue Kellan leaves work at 10 am. After stopping at the bank, he pulls out onto the highway to head home. Right as he turns onto the highway, a car full of 6 men dressed in masks rush into the bank behind him. Using Signal Detection Theory, predict why he may or may notice. Person #1 - Create an explanation and Person #4 create an alternative. Be ready to share in 3 minutes.

*Sensation- Thresholds 100 Percentage of correct detections 75 50 Subliminal stimuli 25 0 Low Absolute threshold Intensity of stimulus Medium § Subliminal §When stimuli are below one’s absolute threshold for conscious awareness (Advertisements…)

*Sensation- Thresholds §Weber’s Law- to perceive as different, two stimuli must differ by a constant minimum percentage § light intensity- 8% § weight- 2% § tone frequency- 0. 3% *Using one category from above, create a real-world example Sensory adaptation- diminished sensitivity as a consequence of constant stimulation § 1. Hit your forearm. Stop and respond. § 2. Continuously hit your forearm for 30 sec. § …Hot peppers?

Ernst Heinrich Weber (1795– 1878) was one of the first people to approach the study of the human response to a physical stimulus in a quantitative fashion. His law states that the just-noticeable difference between two stimuli is proportional to the magnitude of the stimuli. Gustav Theodor Fechner (1801– 1887) later offered an elaborate theoretical interpretation of Weber's findings, in which he attempted to describe the relationship between the physical magnitudes of stimuli and the perceived intensity of the stimuli

*Vision §Transduction §conversion of one form of energy to another §in sensation, transforming of stimulus energies into neural impulses §(sensory stimuli > transduction to neural message > brain)

*Vision §Wavelength §the distance from the peak of one wave to the peak of the next (which distinguish color differences) §Hue §dimension of color determined by wavelength of light §Intensity §amount of energy in a wave determined by amplitude §brightness §loudness

* Vision- Physical Properties of Waves Short wavelength=high frequency (bluish colors, high-pitched sounds) Great amplitude (bright colors, loud sounds) Long wavelength=low frequency (reddish colors, low-pitched sounds) Small amplitude (dull colors, soft sounds)

The spectrum of electromagnetic energy

*Vision

*Vision §Pupil- adjustable opening in the center of the eye §Iris- a ring of muscle that forms the colored portion of the eye around the pupil and controls the size of the pupil opening §Lens- transparent structure behind pupil that changes shape to focus images on the retina §Retina- the light-sensitive inner surface of the eye, containing receptor rods and cones plus layers of neurons that begin the processing of visual information Fovea- central point in the retina, around which the eye’s cones cluster §http: //youtu. be/c. FVb. Ln. XWn 6 A

*Vision

*Vision §Accommodation- the process by which the eyes lens changes shape to help focus near or far objects on the retina §http: //youtu. be/h. MHKJF 31 l. Bg

*Vision §Acuity- the sharpness of vision §Nearsightedness- condition in which nearby objects are seen more clearly than distant objects because distant objects in front of retina §Farsightedness- condition in which faraway objects are seen more clearly than near objects because the image of near objects is focused behind retina

* Retinas Reaction to Light- Receptors §Rods §peripheral retina §detect black, white and gray §twilight or low light §Cones §near center of retina §fine detail and color vision §daylight or well-lit conditions § http: //youtu. be/15 P 8 q 35 v. NHw

*Vision- Receptors in the Human Eye Cones Rods Number 6 million 120 million Location in retina Center Periphery Sensitivity in dim light Low High Color sensitive? Yes No

*Retina’s Reaction to Light §Optic nerve- nerve that carries neural impulses from the eye to the brain §Blind Spot- point at which the optic nerve leaves the eye, creating a “blind spot” because there are no receptor cells located there § http: //youtu. be/a. B_o. Eknhl. W 8

*Vision

*Pathways from the Eyes to the Visual Cortex

*Visual Information Processing §Feature Detectors §nerve cells in the brain that respond to specific features §shape §angle §movement Cell’s responses Stimulus

* Visual Information Processing §Parallel Processing §simultaneous processing of several aspects of a problem simultaneously

* Visual Information Processing §Trichromatic (three color) Theory §Young and Helmholtz §three different retinal color receptors §red §green §Blue § http: //youtu. be/xzm. Xr. C-Yzfc

*Color-Deficient Vision §People who suffer red-green blindness have trouble perceiving the number within the design

* Visual Information Processing Opponent-Process Theoryopposing retinal processes enable color vision “ON” “OFF” red green red blue yellow blue black white black

* Opponent Process- Afterimage Effect

*Visual Information Processing §Color Constancy §Perceiving familiar objects as having consistent color, even if changing illumination alters the wavelengths reflected by the object

*Audition §Audition http: //youtu. be/Pe. Tri. GTENoc §the sense of hearing §Frequency §the number of complete wavelengths that pass a point in a given time §Pitch §a tone’s highness or lowness §depends on frequency

* Vision- Physical Properties of Waves Short wavelength=high frequency (bluish colors, high-pitched sounds) Great amplitude (bright colors, loud sounds) Long wavelength=low frequency (reddish colors, low-pitched sounds) Small amplitude (dull colors, soft sounds)

*The Intensity of Some Common Sounds

*Audition- The Ear § Middle Ear § chamber between eardrum and cochlea containing three tiny bones (auditory ossicles- the smallest bones in the body) that concentrate the vibrations of the eardrum on the cochlea’s oval window § hammer/malleus § anvil/incus § stirrup/stapes § Inner Ear § innermost part of the ear, contining the cochlea, semicurcular canals, and vestibular sacs § Cochlea § coiled, bony, fluid-filled tube in the inner ear through which § http: //youtu. be/ah. Cb. Gjasm_E § EXPLAIN WHAT IS HAPPENING IN YOUR EAR AS YOU HEAR:

*Audition §Place Theory §the theory that links the pitch we hear with the place where the cochlea’s membrane is stimulated §Frequency Theory §the 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 § #1 and #4, say something to your partner in two different pitches. Partners- EXPLAIN WHY/HOW WE HEAR DIFFERENCES IN PITCH USING BOTH THEORIES. Which do you agree with and why?

*Audition §Conduction Hearing Loss §hearing loss caused by damage to the mechanical system that conducts sound waves to the cochlea § http: //youtu. be/B 6 w. KNEw. Ys 4 M §Nerve (Sensorineural) Hearing Loss §hearing loss caused by damage to the cochlea’s receptor cells or to the auditory nerve § http: //youtu. be/Yp. Ipt. QSEEj. Y

*Audition §Older people tend to hear low frequencies well but suffer hearing loss for high frequencies Amplitude required for perception relative to 20 -29 year-old group 1 time 10 times 1000 times 32 64 128 256 512 1024 2048 4096 8192 16384 Frequency of tone in waves per second Low Pitch High

*Touch § Skin Sensations § pressure § only skin sensation with identifiable receptors § warmth § cold § pain

*Pain §Gate-Control Theory http: //youtu. be/vn. Ch. L 9 VSme. Q §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

*Taste §Taste Sensations §Sweet= §Sour= §Salty= §Bitter= §Umami= §Sensory Interaction §the principle that one sense may influence another §as when the smell of food influences its taste §Apply to real-life example involving other senses.

* Smell: Receptor cells>Olfactory bulb>Olfactory Nerves to Temporal lobe and primary smell cortex>Limbic system w memory and emotions Olfactory nerve Olfactory bulb Nasal passage Receptor cells in olfactory membrane

*Age, Sex and Sense of Smell Number of correct answers Women and young adults have best sense of smell 4 Women 3 Men 2 0 10 -19 20 -29 30 -39 40 -49 50 -59 60 -69 Age Group 70 -79 80 -89 90 -99

*Body Position and Movement §Kinesthesis http: //youtu. be/q 6 -Dmv. Rjc 0 Q §the system for sensing the position and movement of individual body parts §Vestibular Sense http: //youtu. be/q 39 A 9 r. I 2 rew §the sense of body movement and position §including the sense of balance