Myers’ PSYCHOLOGY (8th Ed) Chapter 5 Sensation zAP Psychology

Sensation zSensation ya process by which our sensory receptors and nervous system receive and represent stimulus energy zPerception ya process of organizing and interpreting sensory information, enabling us to recognize meaningful objects and events

Sensation zBottom-Up Processing yanalysis that begins with the sense receptors and works up to the brain’s integration of sensory information zTop-Down Processing yinformation processing guided by higher- level mental processes yas when we construct perceptions drawing on our experience and expectations

Sensation- Basic Principles zPsychophysics ystudy of the relationship between physical characteristics of stimuli and our psychological experience of them yLight- brightness ySound- volume yPressure- weight yTaste- sweetness

Sensation- Thresholds zAbsolute Threshold yminimum stimulation needed to detect a particular stimulus yusually defined as the stimulus needed for detection 50% of the time zDifference Threshold yminimum difference between two stimuli that a subject can detect 50% of the time yjust noticeable difference (JND) yincreases with magnitude

Sensation- Thresholds zSignal Detection Theory ypredicts how and when we detect the presence of a faint stimulus (signal) amid background stimulation (noise) yassumes that there is no single absolute threshold ydetection depends partly on person’s xexperience xexpectations xmotivation xlevel of fatigue

Sensation- Thresholds zWhen stimuli are detectable less than 50% of the time (below one’s absolute threshold) they are “subliminal” LowAbsolute threshold Medium Intensity of stimulus Percentage of correct detections Subliminal stimuli

Sensation- Thresholds zWeber’s Law- to perceive a difference between two stimuli, they must differ by a constant proportion ylight intensity- 8% yweight- 2% ytone frequency- 0.3% zSensory adaptation- diminished sensitivity with constant stimulation

Vision- Stabilized Images on the Retina

Vision zTransduction- conversion of one form of energy to another zWavelength- the distance from the peak of one wave to the peak of the next zHue- dimension of color determined by wavelength of light zIntensity- amount of energy in a wave determined by amplitude ybrightness yloudness

Vision- Spectrum of Electromagnetic Energy

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

Vision zPupil- adjustable opening in the center of the eye zIris- a ring of muscle the forms the colored portion of the eye around the pupil and controls the size of the pupil opening zLens- transparent structure behind pupil that changes shape to focus images on the retina

Vision

zAccommodation ychange in shape of lens yfocus near objects zRetina yinner surface of eye ylight sensitive ycontains rods and cones ylayers of neurons ybeginning of visual information processing

Vision zAcuity- the sharpness of vision zNearsightedness ynearby objects seen more clearly ylens focuses image of distant objects in front of retina zFarsightedness yfaraway objects seen more clearly ylens focuses near objects behind retina

Vision zNormalNearsighted Farsighted Vision VisionVision

Retina’s Reaction to Light- Receptors zCones ynear center of retina (fovea) yfine detail and color vision ydaylight or well-lit conditions zRods yperipheral retina ydetect black, white and gray ytwilight or low light

Retina’s Reaction to Light zOptic nerve- nerve that carries neural impulses from the eye to the brain zBlind Spot- point at which the optic nerve leaves the eye, creating a “blind spot” because there are no receptor cells located there zFovea- central point in the retina, around which the eye’s cones cluster

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

Pathways from the Eyes to the Visual Cortex

Visual Information Processing zFeature Detectors yneurons in the visual cortex respond to specific features yshape yangle ymovement Stimulus Cell’s responses

How the Brain Perceives

Illusory Contours

Visual Information Processing zParallel Processing ysimultaneous processing of several dimensions through multiple pathways ycolor ymotion yform ydepth

Visual Information Processing Scene Retinal processing: Receptor rods and cones  bipolar cells  ganglion cells Feature detection: Brain’s detector cells respond to elementary features-bars, edges, or gradients of light Abstraction: Brain’s higher-level cells respond to combined information from feature-detector cells Recognition: Brain matches the constructed image with stored images

Visual Information Processing zTrichromatic (three color) Theory yYoung and Helmholtz ythree different retinal color receptors xred xgreen xblue

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

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

Opponent Process- Afterimage Effect

Audition 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

The Intensity of Some Common Sounds

Audition- The Ear Outer Ear Auditory Canal Eardrum Middle Ear hammer anvil stirrup Inner Ear oval window cochlea basilar membrane hair cells

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

How We Locate Sounds

Audition Conduction Hearing Loss hearing loss caused by damage to the mechanical system that conducts sound waves to the cochlea Nerve Hearing Loss hearing loss caused by damage to the cochlea’s receptor cells or to the auditory nerve

Audition zOlder people tend to hear low frequencies well but suffer hearing loss for high frequencies 1 time 10 times 100 times 1000 times Frequency of tone in waves per second LowPitchHigh Amplitude required for perception relative to year-old group

Touch zSkin Sensations ypressure xonly skin sensation with identifiable receptors ywarmth ycold ypain

Pain zGate-Control Theory ytheory that the spinal cord contains a neurological “gate” that blocks pain signals or allows them to pass on to the brain y“gate” opened by the activity of pain signals traveling up small nerve fibers y“gate” closed by activity in larger fibers or by information coming from the brain

Taste zTaste Sensations- biological wisdom, 200 ysweet ysour ysalty ybitter yUMAMI zSensory Interaction yone sense may influence another yas when the smell of food influences its taste ySynaesthesia- one sense triggers another???

Smell Illustration p. 231 Receptor cells in olfactory membrane Nasal passage Olfactory bulb Olfactory nerve

Smells evoke memories! z20,000 breaths a day, OLFACTION zJust like taste, smell is a chemical sense. z5 million receptor cells at the top of each nostril. Babies recognize Mom’s scent! zWe can detect smell but it is hard to describe them. Easier to explain sounds. zWe have our own chemical smell signature except for identical twins…

Age, Sex and Sense of Smell Women Men Age Group Number of correct answers Women and young adults have best sense of smell

Body Position and Movement- the real 6 th Sense zKinesthesis- 200 muscles for 1 step! ythe system for sensing the position and movement of individual body parts zVestibular Sense ythe sense of body movement and position- biological gyroscope. yincluding the sense of balance- inner ear, semicircular canals- vestibular sacs, cochlea, cerebellum- helps you maintain balance.