Sensation and Perception Unit 3 Chapter 4 Students will explain the processes of sensation and perception and describe the interaction between the person and the environment to determine determining perception

Basic Concepts sensation- stimulation of sense organs –converted into neural impulses perception- selection, organization, and interpretation of sensory input –meaningful experiences psychophysics- study of how physical stimuli are translated into psychological experiences P.23 Examine the processes of sensation and perception and elaborate on how they interact.

Thresholds: Looking for Limits thresholds- dividing point between energy levels that do and do not have a detectable effect –absolute threshold: minimum stimulus intensity detected –just noticeable difference: smallest difference in stimulus intensity that a specific sense can detect P.24 Explain the concepts of threshold and adaptation

Examples of Absolute Thresholds SenseAbsolute Threshold Vision A candle flame seen at 30 miles on a dark clear night Hearing The tick of a watch under quiet conditions at 20 feet Taste One teaspoon of sugar in two gallons of water Smell One drop of perfume diffused into entire volume of a six room apartment Touch The wing of a fly falling on your cheek from a distance of 1 centimeter P.24 Explain the concepts of threshold and adaptation

Signal Detection Theory proposes that detection of stimuli involves decision processes as well as sensory processes, both influenced by variety of factors besides stimulus intensity –expectations –level of “noise”

Perception Without Awareness subliminal perception- registration of sensory input without conscious awareness –below threshold –money, sex, religion religion

Sensory Adaptation gradual decline in sensitivity to prolonged stimulation continued exposure = adaptation to stimulus automatic process that keeps people tuned into changes rather than constants in their sensory input

Our Sense of Sight: The Visual System Unit 3 P.26 Describe the visual, sensory and auditory sensory systems.

The Stimulus: Light light- form of electromagnetic radiation that travels as a wave –Varies in both amplitude and wavelength Amplitude affects perception of brightness Wavelength affects perception of color P.25 List forms of physical energy for which humans and nonhuman animals do and do not have sensory receptors.

The Eye: A Living Optical Instrument cornea- provides 2/3 of eyes total power lens- focuses light rays on the retina retina- absorbs light, processes images, sends visual info to brain pupil- permits light to pass into eye P.26 Describe the visual, sensory and auditory sensory systems.

Visual Receptors: Rods and Cones RODS million rods night vision and peripheral vision sensitive to dim light CONES million cones daylight vision and color vision visual acuity- sharpness and precise detail P.26 Describe the visual, sensory and auditory sensory systems.

Visual Deficiencies Nearsightedness close objects seen clearly but distant objects appear blurry light falls short of retina eyeball is too long Farsightedness distant objects seen clearly but close objects appear blurry light falls behind retina eyeball is too short P.26 Describe the visual, sensory and auditory sensory systems.

Visual Adaptation Dark Adaptation process by which the eyes become more sensitive to light in low illumination Complete in 30 minutes Light Adaptation process whereby eyes become less sensitive to light in high illumination Improves visual acuity

Viewing the World in Color trichromatic theory- human eye has three types of receptors with differing sensitivities to different light wavelengths –red, green and blue –“color mixing” allows for all colors afterimage- visual image that persists after a stimulus is removed –color will be complement of original color

Perceiving Forms, Patterns, and Objects Unit 3

Perceptions are Subjective same visual input can result in radically different perceptions perceptual set- readiness to perceive a stimulus is a particular way inattentional blindness- involves failure to see visible objects or events because attention is focused elsewhere

Looking at the Whole Picture: Gestalt Principles Figure and Ground figure is thing being looked at, while ground is background against which it stands figures appear closer, stand out and have more substance P.28 Explain Gestalt’s principles of perception.

Gestalt Principles Proximity things that are near one another seem to belong together P.28 Explain Gestalt’s principles of perception.

Gestalt Principles Closure group elements to create completeness fill in gaps P.28 Explain Gestalt’s principles of perception.

Gestalt Principles Similarity tendency to group stimuli that are similar same characteristics P.28 Explain Gestalt’s principles of perception.

Gestalt Principles Simplicity Tendency to group elements that combine to form a good figure Organize forms in simplest way possible P.28 Explain Gestalt’s principles of perception.

Gestalt Principles Continuity follows in direction led connect points that result in straight or gently curved lines that create “smooth” paths P.28 Explain Gestalt’s principles of perception.

Perceiving Depth of Distance Binocular Cues clues about distance based on differing views of the two eyes retinal disparity- images projected to different locations on right and left retinas convergence- sensing the eyes converging toward each other as they focus on closer objects Monocular Cues clues about distance based on the image in either eye alone motion parallax- images projected at different distances moving across retina at different rates pictorial depth cues- clues about distance given in a flat picture given in a flat picture depth perception- interpretation of visual cues that indicate how near or far away objects are P.29 Describe binocular and monocular depth cues.

Phi Phenomenon illusion of movement created by presenting visual stimuli in rapid succession illusion of movement created by presenting visual stimuli in rapid succession our perceptions fill in the gaps to perceive motion our perceptions fill in the gaps to perceive motion

Stroboscopic Photography

Our Sense of Hearing: The Auditory System

The Stimulus: Sound sound waves are vibrations of molecules that travel through physical medium –wavelength described in terms of frequency cycles per second, hertz (Hz) –amplitude described in terms of loudness measured in decibels (dB)

Sensory Processing in the Ear external ear –vibration of air molecules middle ear –vibration of movable bones inner ear –waves in a fluid

The human ear pinna- sound collecting bone hammer, anvil, stirrup- amplify tiny changes in air pressure cochlea- contains receptors for hearing

Our Chemical Senses: Taste and Smell

Taste: The Gustatory System Chemical substances that are soluble Receptors are clusters of taste cells on taste buds –short life of 10 days –perception depend on patterns from receptors Four primary tastes –sweet, sour, salty, bitter

Smell: The Olfactory System chemical substances-volatile ones that evaporate and spread throughout the air –dissolved in fluid, mucus in the nose olfactory cilia- hairlike structures in upper portion of nasal passages –short life (30-60 days) Sensory adaptation = 4 minutes

Our Sense of Touch conversion of physical sensation into a psychological experience mechanical, thermal and chemical energy –pressure of touch in warmth, cold and pain P.27 Describe other sensory systems, including olfaction and gustation, and identify skin senses, kinesthesis, and vestibular sense.

Puzzles in Pain Perception Pain Pathways 1. Fast- registers localized pain and relays it to cortex in fraction of a second 2. Slow- conveys longer lasting, aching or burning pain that comes after initial injury Gate Control Theory Incoming pain sensations must pass through “gate” in spinal cord that can be closed, blocking ascending pain signals Cognitive and emotional processes block pain signals

Our Other Systems Kinesthetic monitors positions of various body parts receptors located in joints and muscles Vestibular responds to gravity and keeps you informed about you body’s location in space provides the sense of balance and equilibrium receptors located within semicircular canals of ear P.27 Describe other sensory systems, including olfaction and gustation, and identify skin senses, kinesthesis, and vestibular sense.