psych ch. 4 sensation and perception

Sensation

• the process by which sensory organs in the eyes, ears, nose, mouth, skin, and other tissues receive and detect stimuli

• Data-based processing

Perception

•  the organization and interpretation of sensory stimuli by the brain

• Knowledge-based processing

Psychophysics

the study of the relationships between the physical characteristics of stimuli, such as their intensity, and our psychological experience of them

Absolute threshold

• he minimum stimulation needed to detect a particular stimulus 50% of the time

• goes from nothing to something attainable

Just noticeable difference (JND)

the minimum difference between two stimuli required for detection 50% of the time

Weber’s law

just noticeable difference (JNDs) are proportional to the size of the original stimulus

examples of absolute threshold

• a bees wing touching you

• a tick of a clock far away

• one drop of perfume through out a six-room apartment

• a flame 30 miles

• teaspoon of sugar in 2 gallons of water

Human sensory system

• Vision

• Hearing (Audition)

• Smell (Olfaction)

• Taste (Gustation)

• Somatosenses

• Touch

• Vestibular sense

• Kinesthesis

receptor cells

Specific ____ for each sense stimulate neurons in the central nervous system

transduce

• Receptor cells ___ sensory input from the environment (sights, sounds, smells)

• to convert something, like energy or a message, into another form

Rods

• concentrated in the periphery of the retina

• black and white vision

• most active in dim illumination

cones

• concentrated in the center of the retina (fovea)

• color vision

• most active in bright illumination

Bottom-up processing

• analysis that begins with the sensory receptors and works up to the brain’s integration of sensory information

• You start with the sensory input and build your perception from there.

• raw data

• letters to reading

Top-down processing

• information processing guided by higher-level mental processes, as when we construct perceptions drawing on our experience and expectations

• You use what you already know to interpret and understand the sensory input.

priming

• prior information will alter what we expect to perceive

context

The ___ in which we receive information also changes what we perceive

perceptual parsing

Our visual system divides everything we see into components

law of Proximity

objects close to each other are perceived as a group

Law of Similarity

we perceive elements as a group if they're similar in shape, size, color, or other characteristics

Closure

when we look at a complex arrangement of visual elements, we tend to look for a single, recognizable pattern.

Gestalt

the idea that we tend to perceive objects and scenes as whole, organized patterns rather than just as a collection of individual parts

binocular depth cue

broader ability to see and understand the world using both eyes

binocular disparity

specific difference in the images seen by each eye that helps the brain perceive depth.

convergence

• binocular depth cue in which the eyes rotate inward to focus on a close object

• signals the brain about the distance of the object:

convergence; closer

the greater the ___ the ___ the object is to the observer

retinal disparity

• Interposition

• Linear perspective

• Texture gradient

• Relative Size

Interposition

When one object is in front of another, it partially blocks the view of the other object, and this partially blocked object appears more distant.

relative size

If two objects are similar in actual size, but one is farther away, it appears to be smaller. We interpret the larger object as being closer

linear perspective

When two lines start off parallel, then come together, where they converge appears farther away than where they are parallel.

texture gradiant

When objects are closer, it is easier to see their texture. As they get farther away, the texture becomes less visible. The more apparent the texture, the closer the object appears.

Relative Motion Parallax

• Distance of objects from viewer determines their relative motion

• Nearby objects appear to pass quickly

• Distant objects appear to pass more slowly

Perceptual Constancies

Refers to the ability to retain an unchanging percept of an object despite variations in the retinal image

examples Perceptual Constancies

• Size constancy

• Shape constancy

• Lightness constancy

size constancy

• An object is perceived as maintaining its size, regardless of the image projected on the retina

• knowing the size whether they are far or near

shape constancy

An object is perceived as maintaining its shape, regardless of the image projected on the retina.

Lightness Constancy

to the ability of the human visual system to perceive the brightness of an object as being consistent, even when the lighting conditions change.

color constancy

ability of the human visual system to perceive the color of an object as constant, even when the lighting conditions change, altering the wavelengths of light reflected from the object.

sensory adaption

• a natural lessening of awareness of unchanging conditions

• very valuable for survival

subliminal

which are well beneath our absolute thresholds

signal detection theory

Explains how internal and external factors influence our ability to detect weak signals in the environment.

wavelength

he distance from one wave hump to the next (like the distance between the crests of waves rolling in the ocean;

gama waves

short wavelengths and are located on the far left of the spectrum.

long wave length

wave length on the far right spectrum

light

an electromagnetic wave, composed of fluctuating electric and magnetic fields zooming from place to place at a very fast rate.

cornea

• This clear outer layer over the colored portion of the eye

• shielding the eye from damage by dust, bacteria, or even a poke,

• focusing incoming light waves

• 65–75% of the focusing ability of the eye comes from this

Iris

• Directly behind the cornea is the donut-shaped

pupil

• iris muscle relaxes, enlarging the ___ to allow more light inside the eye.

• black hole in the center of the iris

accommodation

he lens specializes in focusing incoming light, but it can also change shape in order to adjust to objects near and far,

vestibular sense

helps the body maintain balance as it deals with the effects of gravity, movement, and position.

illusion

is a perception that is incongruent with actual sensory data, conveying an inaccurate representation of reality

continuity

Parts tend to be perceived as members of a group if they head in the same direction.

Connectedness

Connected objects are perceived as a group.

cochlea

• primary component of the ear

• converts sound waves into neural signals.

• These vibrations are transmitted to the fluid

• When the hair cells are stimulated, they generate electrical signals

sound waves

: Sound waves are rhythmic vibrations that travel through air and other mediums, caused by vibrating objects.