unit 3

Sensation

Sensation

the process of detecting a physical stimulus

ex of sensation

light, sound, heat, or pressure

Perception

the process of integrating, organizing, and interpreting sensations

bottom-up processing

information processing that emphasizes the importance of the sensory receptors in detecting the basic features of a stimulus in the process of recognizing a whole pattern

• also called data-driven processing

• typically occurs when you’re looking at something new or ambiguous, collecting as much visual information as you can

top-down processing

information processing that emphasizes the importance of the observer's knowledge, expectations, and other cognitive processes in arriving at meaningful perceptions

• also called conceptually-driven processing

ex. of top-down processing

having emotions attached to seeing different people

Sensory receptors

specialized cells unique to each sense organ that respond to a particular form of sensory stimulation (by some form of energy)

• once they detect information transduction occurs

transduction

a process by which a form of physical energy is converted into a coded neural signal that can be processed by the nervous system

absolute threshold

the smallest possible strength of a stimulus that can be detected half of the time

difference threshold/just noticeable difference

the smallest possible difference between two stimuli that can be detected half of the time

ex. of difference threshold/just noticeable difference

what point you notice the slight change of volume when listening to music

Weber’s law

a principle of sensation that holds that the size of the just noticeable difference will vary depending on its relation to the strength of the original stimulus, the size of a just noticeable difference is a constant proportion to the size of the initial stimulus

ex. of Weber’s law

holding a pebble will notice a difference if another pebble is added, if you are holding a heavy rock and the pebble is added you probably won't notice a difference

signal detection theory

predicts how and when we detect the presence of a faint stimulus or signal, it assumes that there is no single absolute threshold and that detection depends partly on a person's experience, expectations, motivation, and level of fatigue, if you detect the absolute threshold it depends on a variety of factors

Sensory adaptation

the decline in sensitivity to a constant stimulus

Subliminal perception

the perception of stimuli that are below the threshold of conscious awareness

how we see

We see light which is one of the different kinds of electromagnetic energy that travels in the form of waves a wavelength

wavelength

the distance from one wave peak to another

• we are only capable of visually detecting a minuscule portion of the electromagnetic energy range

Where does light first enter through?

cornea

cornea

a clear membrane covering the visible part of the eye that helps gather and direct incoming light

pupil

the black opening in the middle of the iris that changes size to let in different amounts of light

iris

the colored part of the eye which is the muscle that controls the size of the pupil

lens

the transparent structure located behind the pupil that actively focuses or bends light as it enters the eye (called accommodation) so that the light falls on the retina

retina

the thin membrane lining the back of the eyeball and contains the sensory receptors for vision

rods

long thin blunt sensory receptors of the eye that are highly sensitive to light but not color, they are primarily responsible for peripheral vision and night vision

cones

the short thick pointed sensory receptors of the eye that detect color and are responsible for color vision and visual acuity

what transduces light energy into neural impulses?

rods and cones

fovea

small area in the center of the retina composed entirely of cones where visual information is most sharply focused

ganglion cells

also in the retina, specialized neurons that connect to the bipolar cells these bipolar cells connect the rods and cones to the ganglion cells, and the bundled axons of the ganglion cells form the optic nerve

optic nerve

a thick nerve that exits the back of the eye and carries visual information to the visual cortex of the brain

optic disk

in the retina, does not have any rods or cones it's where the optic nerve exits the back of the eye creating a blind spot which is the point at which the optic nerve leaves the eye producing a small gap in the field of vision

optic chasm

the point in the brain where the optic nerve fires from each eye meet and partly cross over to the opposite side of the brain

color

the perceptual experience of different wavelengths of light color involves three factors: hue, saturation, and brightness

hue

the property of wavelengths of light known as color different wavelengths correspond to our subjective experience of different colors

saturation

the property of color that corresponds to the purity of a light wave

brightness

the perceived intensity of a color which corresponds to the amplitude of the light wave

two theories of different stages of color vision

the young-Helmholtz trichromatic theory and the opponent process theory

the young-Helmholtz trichromatic theory

the sensation of color results because cones in the retina are especially sensitive to either red light (long wavelengths), green light (medium wavelengths), or blue light (short wavelengths), some overlap of those

Which theory helps to explain color blindness

Young-Helmholtz trichromatic theory

color blindness

color deficiency or weakness in which an individual cannot distinguish between certain colors

• most common type is red-green to individuals who have this type red and green look the same

The opponent process theory

color vision is the product of opposing pairs of color those opposing receptors paris are red green blue yellow and black and white when one color of the color pair is stimulated the other pair is inhibited

Whic theory helps explain the experience of after-image?

The opponent process theory

after-image

occurs after the original source of stimulation is no longer present

feature-detectors

nerve cells in the brain that respond to specific features of a stimulus such as shape, angle, or movement that the brain assembles into the perceived image

Who identified feature-detectors?

Hubbel and Wiesel

parallel processing

the processing of several aspects of a problem simultaneously, the brain divides a visual scene into sub-dimensions such as color, depth, movement, and form and works on each aspect simultaneously

Which principle states that two stimuli must differ by constant proportion for their difference to be perceptible?

Weber’s law

How does bottom-up processing contribute towards sensory information processing?

By starting with sensory input and building up towards creating an overall perception

How does signal detection theory explain our perception in noisy environments?

It suggests we perceive stimuli differently based on decision-making processes and psychological factors, not just sensory information