Chapter 4 Sensation and Perception Psychology

Sensation

Is the stimulation of sense organs

Perception

The selection, organization and interpretation of sensory input

Light

A form of electromagnetic radiation, travels as a wave.

Amplitude

Affects the perception of brightness and loudness

Wavelength

affects the perception of color

Purity

influences the perception of saturation (richness of color) and Timbre

Eye

Living optical instrument

Lens

A transparent eye structure that focuses the light rays falling on the retina and facillitates

Accomodation

Occurs when the curvature of the lens adjusts to alter the visual focus

Nearsightedness(myopia)

Close objects are seen clearly but distant objects appear blurry.

Farsightedness

Distant objects are seen clearly but close objects appear blurry

Cataract

The lens is clouded

What are some visual problems

Nearsightedness

Farsightedness

Cataracts

Iris

The colored ring of muscle surrounding the pupil

Pupil

The opening in the center of the iris that helps regulate the amount of light passing into the rear chamber of the eye

Retina

Neural tissue lining the inside back surface of the eye; it absorbs light, processes images, and sends visual information to the brain.

Optic Disc

A hole in the retina

Blind Spot

The part of the image that falls on the optic disc which you cannot see

What are the two types of receptors in the retina

Rods

Cones

Rods

Play a key role in night vision and peripheral vision.

Cones

Play a key role in daylight vision and color vision

Fovea

A tiny spot in the center of the retina that contains only cones. Visual activity is greatest at this spot

Dark adaptation

Process in which eyes become more sensitive to light in low illumination.

Light adaptation

Process whereby the eyes become less sensitive to light in high illumination

Receptive field of a visual cell

The retinal area that when stimulated, affects the firing of that cell

Optic Chiasm

The point at which the axons from the inside of half of each eye cross over and then project to the opposite half of the brain

Feature detectors

Highly specialized neurons that respond selectively to very specific features of more complex stimuli

What are the two kinds of color mixing

Subtractive 

Additive

Subtractive color mixing

Works by removing some wavelengths of light, leaving less light than was originally there (mixing pigments)

Additive color mixing

Works by superimposing lights putting more light in the mixture that exists in any one light by itself.

Trichromatic Theory

The human eye has three types of receptors with different sensitivities to different light wavelengths

Colorblindness

A variety of deficiencies in the ability to distinguish among colors

Most dichromats are what?

Colorblind

Complementary colors

Pairs of colors that produce gray tones when mixed

Afterimage

Visual image that persists after a stimulus is removed

Opponent Process Theory

Color perception depends on receptors that make antagonistic responses to three pairs of colors

Reversible image

An image that can be interpreted in many ways

Perceptual set

A readiness to perceive a stimulus in a particular way

Inattentional Blindness

The failure to see fully visible objects of events in a visual display because one’s attention is focused elsewhere.

Feature Analysis

The process of detecting specific elements in visual input and assembling them into a more complex form

Bottom Up Processing

Progression from individual elements to the whole

Top Down Processing

Progression from the whole to the elements

What are the two types of processing

Bottom Up and Top Down

Gestalt Psychology

The whole can be greater than the sum of its parts

Phi Phenomenom

The illusion of movement by presenting visual stimuli in rapid succession

Gestalt Principles of perceptual organization

Help explain some of the factors that influence form perception

Figure and Ground

Fundamental way in which people organized visual perceptions

Proximity

Elements that are close to one another

Closure

Viewers tend to supply missing elements to close or complete a familiar figure

Similarity 

Elements that are similar tend be grouped together

Simplicity

Viewers tend to organize elements in the simplest way possible

Continuity

Viewers tend to see elements in ways that produce smooth coordinates

Perceptual Hypothesis

An interference about what form could be responsible for a pattern of sensory stimulation

Depth Perception

Interpretation of visual cues that indicate how near or far away objects are

Binocular depth cues

Clues about distance based on the differing views of the two eyes

Retinal Disparity

Objects within 25ft project images to slightly different locations on the right and left retina, so the right and left eyes see different views

Monocular Depth Cues

Cues about distance based on the image from either eye alone

Pictorial depth cues

Cues about distance that can be given in a flat picture

How many Pictorial depth cues are there

Six

Perceptual Constancy in vision

A tendency to experience a stable perception in the face of continually changing sensory input

Visual Illusion

Inexplicable discrepancy between the appearance of a visual stimulus and its physical reality

Ames room

Trapezoid room, one side bigger other smaller

Moon Illusion

Moon seems larger when closer to horizon

Frequency

Pitch

What are the physical properties of sound

Frequency

Amplitude

Timbre

External Ear

Pinna - sound collecting cone

Middle Ear

Contains Ossicles, Hammer, anvil, and Stirrup. Amplify tiny changes in air pressure

Inner ear

Cochlea and Basilar Membrane

Cochlea

Fluid filled, coiled tunnel that contains the receptors for hearing

Basilar Membrane

Holds the auditory receptors called hair cells

Place theory

Perception of pitch corresponds to the vibration of different portions, or places, along the basilar membrane

Frequency Theory

Perception of pitch corresponds to the rate, or frequency, at which the entire basilar membrane vibrates

Gustatory System

Sensory system for taste

Gustatory receptors

Clusters of taste cells found in taste buds

Taste buds

Clusters around tiny bumps on the tongue called papillae

Variations in sensitivity

Non-Tasters, Supertasters, Medium tasters

Olfactory system

The system for smell

Olfactory cilia

Receptors for smell, hair-like structures located in the upper portion of the nasal passages

Somatosensory Cortex

Devoted to processing signals coming from the fingers, lips and tongue

Fast Pathway

That registers localized pain and relays it to the cortex in a fraction of a second

Slow Pathway

Routed through the limbic system, that lags a second or two behind the fast system

What are the two types of Pathways

Fast and Slow