chapter 3: sensation and perception essentials of psychology, by saul kassin ©2004 prentice hall...

CHAPTER 3:Sensation and Perception

Essentials of Psychology,by Saul Kassin

©2004 Prentice Hall Publishing

Sensation and PerceptionSensation and Perception

Measuring the Sensory Experience

Sensation

Perception

Extrasensory Perception

Kassin, Essentials of Psychology - ©2004 Prentice Hall Publishing

• Sensation– The processes by which our sense organs receive

information from the environment.

• Transduction– The process by which physical energy is

converted into sensory neural impulses.

• Perception– The processes by which people select, organize,

and interpret sensations.

Sensation and PerceptionSensation and Perception


Processes of Sensation & PerceptionProcesses of Sensation & Perception


• Psychophysics– The study of the relationship between

physical stimulation and subjective sensations.

• Signal-Detection Theory– The theory that detecting a stimulus is

jointly determined by the signal and the subject’s response criterion.

Measuring Sensory ExperienceMeasuring Sensory ExperienceResearch and TheoryResearch and Theory


• Absolute Threshold– The smallest amount of stimulation that can

be detected.

• Just Noticeable Difference (JND)– The smallest amount of change in a stimulus

that can be detected.

Measuring Sensory ExperienceMeasuring Sensory ExperienceThresholdsThresholds


• Vision: A single candle flame from 30 miles on a dark, clear night

• Hearing: The tick of a watch from 20 feet in total quiet

• Smell: 1 drop of perfume in a 6-room apartment• Taste: 1 teaspoon sugar in 2 gallons of water• Touch: The wing of a bee on your cheek, dropped

from 1 cm

Measuring Sensory Experience Measuring Sensory Experience Absolute Sensory ThresholdsAbsolute Sensory Thresholds


• Vision

• Hearing

• Other Senses

• Keeping the Signals Straight

SensationSensation


VisionVisionThe Electromagnetic SpectrumThe Electromagnetic Spectrum


Vision Vision Structures of the Human EyeStructures of the Human Eye


• Cornea– Clear outer membrane that bends light to focus

it in the eye.

• Pupil– The hole in the iris through which light passes.

• Lens– The structure that focuses light on the retina.

Vision Vision Structures of the Human EyeStructures of the Human Eye


•The rear of the eye where rods and cones convert light into neural impulses.

VisionVisionThe RetinaThe Retina


Optic Nerve• Pathway that carries visual information from the eyeball to the brain.

VisionVisionVisual PathwaysVisual Pathways


• Hubel and Wiesel’s experiment measured the activity of cells in a cat’s visual cortex.

• Cells in the visual cortex that respond only to certain types of visual information, for example, a diagonal line moving up and down, are called feature detectors.

VisionVisionHubel & Wiesel’s ExperimentHubel & Wiesel’s Experiment


• T. Young (1802) & H. von Helmholtz (1852) both proposed that the eye detects three primary colors: red, blue, & green.

• All other colors can be derived by combining these three.

VisionVisionTrichromatic TheoryTrichromatic Theory


• Spectral colors vary from violet-blue to red– 470 to 700 nanometer

wavelength• Opponent colors are

directly across from each other on the wheel.

VisionVisionThe Color WheelThe Color Wheel


VisionVisionTest of Color DeficiencyTest of Color Deficiency


– Color vision is derived from three pairs of opposing receptors. The opponent colors are blue and yellow, red and green, and black and white.

• This theory explains afterimages (a visual sensation that persists after prolonged exposure to and removal of a stimulus) and color deficiency.

VisionVisionOpponent-Process TheoryOpponent-Process Theory


Audition•The sense of hearing

HearingHearingThe Human EarThe Human Ear


– The ability to judge from which direction a sound is coming

• Sounds from different directions are not identical as they arrive at left and right ears.

• The brain calculates a sound’s location by using differences in timing and intensity.

HearingHearingAuditory LocalizationAuditory Localization


HearingHearingCommon Sounds and the Noise They ProduceCommon Sounds and the Noise They Produce


• Conduction Hearing Loss– Caused by damage to the eardrum or bones

in the middle ear.

• Sensorineural Hearing Loss– Caused by damage to the structures of the

inner ear.

HearingHearingHearing DisabilitiesHearing Disabilities


•Structures responsible for the sense of smell

Other SensesOther SensesOlfactory SystemOlfactory System


• Taste buds– Nets of taste-receptor

cells• This is a photograph of the

tongue’s surface (top), magnified 75 times.

• 10,000 taste buds line the tongue and mouth.

• Children have more taste buds than adults do.

• There are four primary tastes: sweet, salty, sour, and bitter.

Other SensesOther SensesTaste Taste


• The Thermal Grill When a person grasps two braided water pipes – one with cold water running through it and one with warm water – the sensation is “burning hot” and painful.

• There are two separate pathways for warmth and cold.

Other SensesOther SensesTemperatureTemperature


• Gate-control Theory– Theory that the spinal cord contains a

neurological “gate” that blocks pain signals from the brain when flooded by competing signals.

• Psychological control– Mind over sensation, distraction

Other SensesOther SensesPainPain


• Kinesthetic System– Structures distributed throughout body that

sense position and movement of body parts.

• Vestibular System– The inner ear and brain structures that

afford a sense of equilibrium.

Other SensesOther SensesCoordinationCoordination


• Synesthesia– Rare condition in which stimulation in one

sensory modality triggers sensations in another sensory modality.

• Each sensory system is designed to operate separately from the others.

• Sensory Adaptation– A decline in sensitivity to a stimulus as a result of

constant exposure.

Keeping the Signals StraightKeeping the Signals Straight


• Perceptual Organization

• Perceptual Constancies

• Depth and Dimension

• Perceptual Set

• The World of Illusions

PerceptionPerception


– Drawings that one can perceive in different ways by reversing figure and ground.

• Gestalt Psychology– School of thought

rooted in the idea that the whole is different from the sum of its parts.

Perceptual OrganizationPerceptual Organization Reversible FiguresReversible Figures


• Proximity– Seeing 3 pair of lines in A

• Similarity– Seeing columns of orange

and red dots in B

• Continuity– Seeing lines that connect

1 to 2 and 3 to 4 in C

• Closure– Seeing a horse in D

Perceptual OrganizationPerceptual Organization Gestalt Laws of GroupingGestalt Laws of Grouping


• Geons (geometric icons) are simple 3D component shapes.

• A limited number are stored in memory.

• Geons are combined to identify essential contours of objects.

Perceptual OrganizationPerceptual OrganizationIdentifying ObjectsIdentifying Objects


• Size Constancy– The tendency to view an object as constant

in size despite changes in the size of the retinal image.

Perceptual ConstanciesPerceptual Constancies


• Depth Perception– The use of visual cues to estimate depth and

distance.

• Convergence– A binocular cue involving the turning inward of

the eyes as an object gets closer.

• Binocular Disparity– A binocular cue whereby the closer an object is,

the more different the image is in each retina.

Depth and DimensionDepth and Dimension


– Distance cues that enable the perception of depth with one eye.

• Relative Image Size• Texture Gradient• Linear Perspective• Interposition• Atmospheric Perspective• Relative Elevation• Familiarity

Depth and DimensionDepth and DimensionMonocular Depth CuesMonocular Depth Cues


• Devised by Eleanor Gibson and Richard Walk to test depth perception in infants and animals.

• Provides visual illusion of a cliff.

• Caregiver stands across the gap.

• Babies are not afraid until about the age that they can crawl.

Depth and DimensionDepth and DimensionThe Visual CliffThe Visual Cliff


• What is seen in the center figures depends on the order in which one looks at the figures:

– If scanned from the left, a man’s face is seen.

– If scanned from the right, a woman’s figure is seen.

• This demonstrates the effects of one’s perceptual set.

Perceptual SetPerceptual Set


• The same physical stimulus can be interpreted differently depending on perceptual set, e.g., context effects.

• When is the middle character the letter B and when is it the number 13?

Perceptual SetPerceptual Set Context EffectsContext Effects


– Illusion in which the perceived length of a line is altered by the position of other lines that enclose it

The World of IllusionsThe World of Illusions The Müller-Lyer Illusion The Müller-Lyer Illusion


• The Case for ESP

• The Case against ESP

• The Continuing Controversy

Extrasensory PerceptionExtrasensory Perception


• Extrasensory Perception (ESP)– The ability to perceive something without

ordinary sensory information. – This has not been scientifically demonstrated.

• Parapsychologists distinguish between three types of ESP:– Telepathy – Mind-to-mind communication– Clairvoyance – Perception of remote events– Precognition – Ability to see future events

The Case for ESPThe Case for ESP


• J. B. Rhine conducted many experiments on ESP using stimuli such as these.

• Rhine believed that his evidence supported the existence of ESP, but his findings were flawed..

The Case against ESPThe Case against ESPESP CardsESP Cards


• The ganzfield procedure

• Researchers disagree about the reliability of studies done to replicate the ganzfield test.

• Visit www.randi.org/ for information about the James Randi Educational Foundation’s million-dollar paranormal challenge.

The Continuing ControversyThe Continuing Controversy


chapter 3: sensation and perception essentials of psychology, by saul kassin ©2004 prentice hall...

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